An ostracod-based calibration function for electrical conductivity reconstruction in lacustrine environments in Patagonia,Southern South America

In the Patagonian region (∼37–56°S) E of the Andes, the salinity and solute composition of lakes is strongly related to their location along the marked W-E decreasing precipitation gradient that is one of the main climatic features of the area. A calibration function (n = 34) based on 12 ostracod species (Ostracoda, Crustacea) was developed by WA-PLS to quantitatively reconstruct electrical conductivity (EC) values as a salinity proxy. The selected one component model had a r² = 0.74 and RMSEP and maximum bias equal to 16% and 31% of the sampled range, respectively, comparable to other published ostracod-based calibration functions. This model was applied to the ostracod record of the closed lake Laguna Cháltel (49°58′S, 71°07′W), comprising seven species and dominated by two species of the genus Limnocythere. In order to evaluate the calibration function’s robustness, the obtained EC values were compared with qualitative lake level and salinity variations inferred through a multiproxy hydrological reconstruction of the lake. Both reconstructions show good overall agreement, with reconstructed EC values in the oligo-mesohaline range (average: 11 060 ± 680 μS/cm) between 4570 and 3190 cal BP, corresponding to the ephemeral and shallow lake phases, and a marked decrease in EC concurrent with a lake level rise, reaching an average EC of 1140 ± 90 μS/cm during the deep lake phase (1720 cal BP to present). The variability in the reconstructed EC values for the ephemeral lake phase showed some inconsistency with the expected trend, which was attributed to time-averaging effects; for its part, the pace of the decrease in EC during the medium-depth phase (3190–1720 cal BP) differed from the expected, which could be due to autigenic effects (redissolution of salts) at the onset of this phase. This comparison not only lends support to the adequacy of the calibration function, but also suggests that its application in the context of a multiproxy study can greatly contribute to distinguish between autigenic and climatic-related controls of paleosalinity in closed lakes, allowing performing more accurate paleoenvironmental inferences on the basis of paleohydrological reconstructions.     

Cloning,expression, and characterization of a thermostable and pH-stable laccase from Klebsiella pneumoniae and its application to dye decolorization

A thermostable and pH-stable laccase from Klebsiella pneumoniae was cloned and expressed in Escherichia coli. The recombinant laccase (rLac) achieved a specific activity of 7.12 U/mg after purification by Ni-affinity chromatography. Optimal enzyme activity was observed at pH 4.0 and 35 °C for 2,2′-azino-bis (3-ethylbenzthiazoline sulfonic acid) (ABTS) oxidization and pH 8.0 and 70 °C for 2,6-dimethoxyphenol (2,6-DMP) oxidization. Thermostability and pH stability studies showed that the rLac was stable over the range of 30–70 °C and pH 5.0–9.0 using 2,6-DMP as substrate. Circular dichroism analysis suggested that the secondary structure of the rLac mainly consisted of α-helix that played a vital role in maintaining laccase activity and revealed the potential mechanisms for the changes in laccase activity under varying pHs (3.0–11.0) and temperatures (20–90 °C). Finally, the rLac could decolorize the tested dyes with high decolorization efficiency.     

Vertical migration of Karenia brevis in the northeastern Gulf of Mexico observed from glider measurements

The toxic marine dinoflagellate, Karenia brevis (the species responsible for most of red tides or harmful algal blooms in the Gulf of Mexico), is known to be able to swim vertically to adapt to the light and nutrient environments, nearly all such observations have been made through controlled experiments using cultures. Here, using continuous 3-dimensional measurements by an ocean glider across a K. brevis bloom in the northeastern Gulf of Mexico between 1 and 8 August 2014, we show the vertical migration behavior of K. brevis. Within the bloom where K. brevis concentration is between 100,000 and 1,000,000 cells L⁻¹, the stratified water shows a two-layer system with the depth of pycnocline ranging between 14–20 m and salinity and temperature in the surface layer being <34.8 and >28 °C, respectively. The bottom layer shows the salinity of >36 and temperature of <26 °C. The low salinity is apparently due to coastal runoff, as the top layer also shows high amount of colored dissolved organic matter (CDOM). Within the top layer, chlorophyll-a fluorescence shows clear diel changes in the vertical structure, an indication of K. brevis vertical migration at a mean speed of 0.5–1 m h⁻¹. The upward migration appears to start at sunrise at a depth of 8–10 m, while the downward migration appears to start at sunset (or when surface light approaches 0) at a depth of ∼2 m. These vertical migrations are believed to be a result of the need of K. brevis cells for light and nutrients in a stable, stratified, and CDOM-rich environment.     

Heterologous expression,refolding and functional characterization of two antifreeze proteins from Fragilariopsis cylindrus (Bacillariophyceae)

Antifreeze proteins (AFPs) provide protection for organisms subjected to the presence of ice crystals. The psychrophilic diatom Fragilariopsis cylindrus which is frequently found in polar sea ice carries a multitude of AFP isoforms. In this study we report the heterologous expression of two antifreeze protein isoforms from F. cylindrus in Escherichia coli. Refolding from inclusion bodies produced proteins functionally active with respect to crystal deformation, recrystallization inhibition and thermal hysteresis. We observed a reduction of activity in the presence of the pelB leader peptide in comparison with the GS-linked SUMO-tag. Activity was positively correlated to protein concentration and buffer salinity. Thermal hysteresis and crystal deformation habit suggest the affiliation of the proteins to the hyperactive group of AFPs. One isoform, carrying a signal peptide for secretion, produced a thermal hysteresis up to 1.53 °C ± 0.53 °C and ice crystals of hexagonal bipyramidal shape. The second isoform, which has a long preceding N-terminal sequence of unknown function, produced thermal hysteresis of up to 2.34 °C ± 0.25 °C. Ice crystals grew in form of a hexagonal column in presence of this protein. The different sequences preceding the ice binding domain point to distinct localizations of the proteins inside or outside the cell. We thus propose that AFPs have different functions in vivo, also reflected in their specific TH capability.     

Toxic strains of the Alexandrium ostenfeldii complex in southern South America (Beagle Channel,Argentina)

During phytoplankton monitoring in the Beagle Channel (≈54°52′ S, 67°32′ W) a previously undetected Alexandrium species was observed in coincidence with mouse bioassay toxicity. Detailed thecal plates analysis using epifluorescence and scanning electron microscopy revealed the presence of the Alexandrium ostenfeldii species complex, showing a mixture of the diagnostic features usually used to discriminate between the morphospecies A. ostenfeldii and A. peruvianum. Cells of the A. ostenfeldii complex were commonly observed during spring after the main annual diatom bloom, when temperatures and salinities were respectively around 7.5–10 °C and 30–30.5 psu, and nutrients showed a seasonal decrease. Toxin analysis by liquid chromatography–mass spectrometry revealed the production of 13-desmethyl spirolide C and 20-methyl spirolide G in cell cultures. The cellular contain of spirolides during exponential phase growth was 0.5906 ± 0.0032 and 0.1577 ± 0.0023 pg cell⁻¹ for 13-desMe-C and 20-Me-G, respectively. A third unknown compound, with a structure resembling that of spirolides was also detected in culture. Moreover, an additional compound with a similar m/z (692) than that of 13-desMe-C but presenting a higher retention time (Rt = 40.5 min) was found in high proportions in mussel samples. PSP toxins were present at low concentration in mussels but were not detected in cultures. These results extend the world-wide distribution of toxic strains of the A. ostenfeldii complex to the Beagle Channel (southern South America), where toxic events have been traditionally linked to the presence of Alexandrium catenella. This is the first confirmed occurrence of spirolides in mussels and plankton from Argentina, which highlights the importance of monitoring these toxins and their producing organisms to protect public health and improve the management of shellfish resources.     

Effects of temperature,salinity and their interaction on growth of Japanese Gambierdiscus spp. (Dinophyceae)

Marine toxic dinoflagellates of the genus Gambierdiscus are the causative agents of ciguatera fish poisoning (CFP), a seafood poisoning that is widespread in tropical, subtropical and temperate regions of the world. In the main island of Japan, distributions of Gambierdiscus australes, Gambierdiscus scabrosus and two phylotypes of Gambierdiscus spp. type 2 and type 3, have been reported. To discuss the bloom dynamics of these Japanese species/phylotypes of Gambierdiscus, first we tested six culture media to optimize growth conditions and then clarified the effects of temperature and salinity and temperature–salinity interactions on growth. All strains of the species/phylotypes tested showed the highest cell yields when they were cultivated in IMK/2 medium. G. australes, G. scabrosus and Gambierdiscus sp. type 2 grew in the range 17.5–30 °C, whereas Gambierdiscus sp. type 3 grew in 15–25 °C. The semi-optimal temperature ranges (≥80% of the maximal growth rate) of the former three species/phylotypes were 19–28 °C, 24–31 °C and 21–28 °C, respectively, whereas that of the latter phylotype was 22–25 °C. Hence, Gambierdiscus sp. type 3 may be adapted to relatively lower water temperatures of ≤25 °C. In contrast, G. australes, G. scabrosus and Gambierdiscus sp. type 2 presumably possess adaptability to relatively high water temperatures. The optimal temperature for G. scabrosus was 30 °C, whereas the optimal temperature for the others was 25 °C. G. australes and Gambierdiscus sp. type 3 grew in a salinity range of 25–40 whereas G. scabrosus and Gambierdiscus sp. type 2 grew in salinity 20–40. Furthermore, the semi-optimal salinity range of G. australes, G. scabrosus, Gambierdiscus spp. type 2 and type 3 were salinity 27–38, 24–36, 22–36 and 29–37, respectively. Among the species/phylotypes, G. scabrosus and Gambierdiscus sp. type 2 grew even at salinity 20 where the others did not grow, thus possessing adaptability to low salinity waters. Our results clearly demonstrate that the optimal and tolerable temperature–salinity conditions differ among Japanese Gambierdiscus species/phylotypes. Considering these results, temperature–salinity interactions may play an important role in bloom dynamics and the distribution of the Gambierdiscus species/phylotypes in Japanese coastal waters.     

Role of calcium in alleviating effect of salinity on germination of Phragmites karka seeds

Phragmites karka (Retz.) Trin, ex. steud, a perennial reed with creeping rhizome from the family Poaceae, is distributed as pure population in brackish water swamps. Populations primarily propagate using ramets but also produce numerous seeds which form part of the seed bank after dispersal and are exposed to extremes of temperature, drought, and salinity stress. Seeds were germinated under a range of salinity (0, 100, 200, 300, 400, 500 mM NaCl) and temperature (10/20 °C, 15/25 °C, 20/30 °C, 25/35 °C, night/day) regimes in 12 h light:12 h dark photoperiod or in complete darkness with 0, 5, 10, 25 mM CaCl₂. Salinity, absence of light and high temperature (25/35 °C) reduced germination while calcium generally reversed this effect, more so at cooler temperature regimes. Calcareous soil around Karachi would help alleviate the salinity effect on the germination of P. karka and facilitate its survival.     

Paleoceanography of the Mauritanian margin during the last two climatic cycles: From planktonic foraminifera to African climate dynamics

The last 220 ka of the MD03-2705 (18° 05.81′ N–21° 09.19′ W) sedimentary sequence, retrieved off the Cape Verde islands, was investigated using a multiproxy approach. Planktonic foraminifera assemblage analyses, coupled with isotopic measurements (δ¹⁸O) from benthic (Planulina wuellerstorfi) and planktonic (Globigerinoides ruber) foraminifera monospecific samples were conducted along the topmost 11 m of the sequence. High resolution X-ray fluorescence measurements (0.5 cm resolution), giving access to major element ratio, have completed the geochemical analyses along the core. Seasonal and annual past sea surface temperatures (SST) were quantitatively reconstructed. Local sea-surface salinity (SSS) changes were then estimated by coupling SST with planktonic δ¹⁸O data. Our data provide a set of both oceanic and continental markers of environmental changes along the north-western African margin. The major changes detected in our record are discussed in the light of the regional paleoceanographic and paleoclimatic history of the last 220 ka. Coupled oceanographic and atmospheric processes portray the climatic evolution of the area, and show strong links among the regional oceanography (water mass advection), the upwelling dynamics and the Intertropical Convergence Zone (ITCZ) migration. An increased upwelling activity (or influence of upwelling filaments) is noted at the end of the two last glacial periods, probably in response to a more southerly position of the ITCZ. Higher SSS are recorded over the area during arid intervals and were tentatively interpreted as signing a southward shift of the Cape Verde Frontal Zone. A detailed coupling between dust advection and SSS values over the site of study was noted during MIS6.5.     

Growth of eight Gambierdiscus (Dinophyceae) species: Effects of temperature,salinity and irradiance

Little is known about how the growth of individual Gambierdiscus species responds to environmental factors. This study examined the effects of temperature (15–34 °C), salinity (15–41) and irradiance (2–664 μmol photons m⁻² s⁻¹) on growth of Gambierdiscus: G. australes, G. belizeanus, G. caribaeus, G. carolinianus, G. carpenteri, G. pacificus and G. ruetzleri and one putative new species, Gambierdiscus ribotype 2. Depending on species, temperatures where maximum growth occurred varied between 26.5 and 31.1 °C. The upper and lower thermal limits for all species were between 31–34 °C and 15–21 °C, respectively. The shapes of the temperature vs. growth curves indicated that even small differences of 1–2 °C notably affected growth potentials. Salinities where maximum growth occurred varied between 24.7 and 35, while the lowest salinities supporting growth ranged from <14 to 20.9. These data indicated that Gambierdiscus species are more tolerant of lower salinities than is generally appreciated. Growth of all species began to decline markedly as salinities exceed 35.1–39.4. The highest salinity tested in this study (41), however, was lethal to only one species, Gambierdiscus ribotype 2. The combined salinity data indicated that differences in salinity regimes may affect relative species abundances and distributions, particularly when salinities are <20 and >35. All eight Gambierdiscus species were adapted to relatively low light conditions, exhibiting growth maxima at 50–230 μmol photons m⁻² s⁻¹ and requiring only 6–17 μmol photons m⁻² s⁻¹ to maintain growth. These low light requirements indicate that Gambierdiscus growth can occur up to 150 m depth in tropical waters, with optimal light regimes often extending to 75 m. The combined temperature, salinity and light requirements of Gambierdiscus can be used to define latitudinal ranges and species-specific habitats, as well as to inform predictive models.     

Effect of the holding time at 15 °C prior to cryopreservation,the thawing rate and the post-thaw incubation temperature on the boar sperm quality after cryopreservation

The aim of the present study was to evaluate the effect of the holding time at 15 °C prior to cryopreservation (2, 4 and 8 h), thawing rate (37 °C for 20 s or 70 °C for 8 s) and post-thaw incubation temperature (15 °C or 37 °C) on the post-thaw boar sperm quality. These are important time periods in the freezing–thawing process which have been less studied. Sperm-rich ejaculate fractions from three healthy boars were collected once a week for five consecutive weeks and were cryopreserved with the lactose-egg yolk extender (LEY). Sperm quality was determined by assessing the motility, the acrosome status, and the sperm plasma membrane integrity at 30, 150 and 240 min of incubation. The results show that with the holding time at 15 °C prior to cryopreservation there was not a clear effect until at least 24 h of holding time. The thawing rate and the post-thaw incubation temperature, however, had a marked effect on sperm quality. When the samples were thawed at 70 °C for 8 s, the sperm viability, motility and some kinetic variables (VCL, VSL, VAP and ALH) were greater than with results observed when the samples were thawed at 37 °C for 20 s. In addition after thawing the sperm samples incubated at 15 °C had a sustained sperm quality for longer, up to 4 h post-thawing.     

Assessment of soil-quality index based on microarthropods in corn cultivation in Northern Italy

The aim of this paper is to assess of the stability and repeatability of the biological soil-quality (BSQ) index over time and at short/long distances in agricultural soils of the Po Valley, Northern Italy, to support its correct use in soil-quality monitoring and is based on soil microarthropods representative of the structure, function and composition of ecological systems, but avoiding classification at the species level. Microarthropods are separated from the soil and weighted using the biological form approach to evaluate their level of adaptation to the soil environment. The field test was organized to assess time and scale effects in a landscape within the coordinates 45°00′ to 45°16′N and 9°50′ to 10°15′E for an estimated area of 200 km². The BSQ had, in different soils cropped with corn and fertilized with sewage sludge, an average value of 76.4 ± 23.5; it appears to be reproducible both over short distances as well as over short periods of time, but no significant differences (p > 0.05) between years nor between farms were observed. In the landscape conditions tested, it appears reproducible and stable at a field and basin scale, though very sensitive to seasonal climatic variations. From a practical point of view, the information reported in this paper contributes to the standardization of the application of BSQ and provides reference values for this index in soils of the Northern Italy cropped with corn.     

The systematic position of Hoplitomerycidae (Ruminantia) revisited

Hoplitomeryx Leinders was originally described only on cranial characters. The type specimens were found during the 1970's in karstic fissure fillings, most likely of Messinian age, in Gargano (Apulia, southeastern Italy), between Poggio Imperiale (41°49′30′ N, 15°21′58′ E) and Apricena (41°47′06′ N, 15°26′41′ E). During the 1990's, Hoplitomeryx remains were also discovered in the lower Tortonian layered calcarenites near Scontrone (Abruzzo, central Italy; 41°45′15.55′ N, 14°02′13.23′ E). The skull fragments, teeth, and jawbones from both localities have been examined. The dental characters had never been described before, and also some maxillaries and jawbones were not part of the original sample that was analyzed to establish the genus. Because they possess two lacrimal orifices and closed metatarsal gulley, hoplitomerycids have been linked more closely with Cervids, and accommodated in Cervoidea. A cladistic analysis of a character-taxon matrix of 121 morphological features (48 cranial, 51 dental and 22 postcranial characters) is performed. The analysis shows that hoplitomerycids stem either between antilocaprids and bovids, or antilocaprids and giraffids. They are not linked directly with cervids. Hoplitomerycids likely stemmed from a primitive ruminant stock, perhaps around 29 Ma when a land bridge connected the Abruzzo-Apulia platform with the Balkans across the Adriatic Sea. In the new land, hoplitomerycids developed a mosaic of apomorphic and homoplastic (convergent) character states that recall those found in other higher ruminants.     

Paleoenvironmental reconstruction of the Early Pleistocene site of Quibas (SE Spain) using a rodent assemblage

In this paper we analyze the rodent assemblage from the Early Pleistocene site of Gruta1 (Quibas karstic complex, Murcia, SE Spain), providing taphonomic comments and paleoecological and paleoclimatic data. The studied assemblage includes 209 identified rodent teeth corresponding to at least four taxa. The karstic source of the site and the low presence of digested remains suggest that the accumulation is scatological in origin, with the influence of predators such as owls; the accumulation also shows certain evidence of slight hydrodynamic sorting. For the area around Quibas/Gruta1 the paleoecological study indicates a predominance of rocky areas (31.7%), forested environments (31.7%) and open dry meadows or shrublands (29.7%), which would indicate a mosaic forest environment, and to a lesser extent the presence of open humid land (5.4%) and areas along streams or ponds (1.5%). The distribution of the bioclimatic spectra yields the highest percentage for a Mediterranean climate (37.5%), while the climatic parameters calculated (MAT = 15 °C, MTW = 25.7 °C, MTC = 4.3 °C, MAP = 390 mm) suggest colder and slightly more humid conditions than today at the time of the deposition of the remains. The data also point to a relative decrease in temperature within the phase in which the site was produced, which possibly occurred during a relative cold period between MIS 36 and MIS 40 according to the age.     

Effects of salt,alkali and salt–alkali mixed stresses on seed germination of the halophyte Salsola ferganica (Chenopodiaceae)

Salsola ferganica L. (Chenopodianceae) is an annual halophytic species. Experiments were carried out in laboratory to determine the effects of temperature, perianths and various types of salinity on seed germination and germination recovery. Seeds were germinated at 6 levels of temperature with perianths, plus perianths and removed perianths in complete darkness for 9 days. The germination responses of the seeds without perianths at 25 °C were determined over a wide range of NaCl, NaHCO₃ or NaCl–NaHCO₃ mixed stress for 13 days. Perianths seriously affected germination as a barrier for seed germination and the optimal temperature was at 25 °C. Highest germination percentage was obtained under control and seed germination was progressively inhibited with the increase of salinity concentration. The negative effect of NaHCO₃ at the same concentration on germination was stronger than that of NaCl and NaCl–NaHCO₃ mixed. When substrate salinity was removed, seeds exposed to a high NaCl concentration (400–800 mM), NaHCO₃ (50–200 mM) and NaCl–NaHCO₃ mixed (100–400 mM) germinated well. Final germination of Salsola ferganica seeds was significantly affected by types of salt at the low salinity (?200 mM) and with increased salinity it was influenced mainly by salinity concentration for various proportion of salt–alkali mixed stress.     

Gelation of high methoxy pectin by acidification with d-glucono-δ-lactone (GDL) at room temperature

Rheological comparisons have been made between preparations of high methoxy pectin (DE ≈ 70%) gelled by acidification with d-glucono-δ-lactone (GDL) on holding for 16 h at 25 °C in the presence of 60 wt% sucrose, and otherwise identical preparations gelled by acidification with citric acid at high temperature and cooling from 90 to 25 °C at 1 °C/min. Two series of experiments were carried out for both methods of acidification. In the first series, the concentration of pectin (c) was held constant at 1.0 wt% and the final pH attained after holding (with GDL) or cooling (with citric acid) was varied from 3.75 to 2.25. In the second series, the final pH was held constant at 3.0 and c was varied from 0.25 to 2.00 wt%. All samples were then heated (1 °C/min) from 25 to 90 °C. Rheological changes on cooling/holding and heating were characterised by low-amplitude oscillatory measurements of storage modulus (G′) and loss modulus (G′′) at 1 rad s^?1 and 0.5% strain, and mechanical spectra were recorded at 25 °C. Selected samples, gelled with GDL, were also characterised by compression testing (at 25 °C), and a direct linear relationship was found between the logarithm of yield stress and log G′.The concentration-dependence of moduli for the samples acidified to pH 3.0 with GDL had the form typical of biopolymer gels, with log G′ versus log c approaching a limiting slope of 2 as c was raised above the minimum critical gelling concentration (c_o ≈ 0.3 wt%). Under all conditions of pH and pectin concentration studied, the values of G′′ (at 25 °C) for the samples acidified with citric acid were higher than those of the corresponding GDL-induced networks. The values of G′ were also higher, except at very low pH (below ～2.7 at c = 1.0 wt%) or very high concentrations of pectin. At pectin concentrations above ～1.5 wt%, the moduli of the samples gelled with citric acid (at pH 3.0) levelled out, or decreased slightly, with the values of G′ dropping below those of the GDL-induced networks towards the end of the concentration range studied (at c ≈ 2 wt%). All samples acidified with citric acid showed gel-like response (G′ > G′′) at 90 °C, attributed to hydrophobic association. The downturn in moduli at 25 °C for high concentrations of pectin is attributed to formation and disruption of strong networks during mixing with citric acid at high temperature (“pregelation”). It is suggested, however, that “weak gels” formed at lower concentrations or at pH values above ～2.7 may enhance gel properties by preserving a continuous network as hydrophobic junctions dissociate on cooling and are replaced by hydrogen-bonded junctions, in contrast to random percolation during gelation with GDL at 25 °C. On re-heating from 25 to 90 °C, the reverse processes (dissociation of hydrogen-bonded structures and formation of hydrophobic associations) were evident in an initial reduction and subsequent increase in moduli, as observed in previous studies. Similar heating traces were obtained for samples acidified with GDL to pH values above ～3.0 (at c = 1.0 wt%) or with pectin concentrations below ～1.0 wt% (at pH 3.0). However, at higher concentrations or lower values of pH (i.e. conditions favourable to extensive intermolecular association) an abrupt decrease in G′, with an accompanying maximum in G′′, was observed on heating through the temperature range ～60–80 °C. This is attributed to excessive hydrophobic association, causing collapse of network structure. It is further suggested that, for samples acidified with citric acid, there is preferential association of chain sequences of high ester content into hydrophobic junctions at 90 °C, leaving sequences with a high content of unesterified carboxyl groups available to form long hydrogen-bonded junctions during cooling, and thus giving gels that are stronger and more resistant to network collapse.     

Holocene environmental changes as recorded by mineral magnetism of sediments from Anguli-nuur Lake,southeastern Inner Mongolia Plateau,China

Two cores, one 1141-cm long (An-S) and the other 885-cm long (An-A), were retrieved from Anguli-nuur Lake (41°18′–24′N, 114°20′–27′E, ～ 1315 masl), one of the largest lakes in the transition zone between a semi-humid and semi-arid climate parallel to the present limit of the southeast monsoon along the southeastern Inner Mongolia Plateau in north China. Mineral-magnetic parameters (χ_lf, ARM, IRM_300mT, SIRM and IRM_? 300mT) were measured on An-S and two additional parameters (χ_ARM and HIRM) and four inter-parametric ratios (χ_ARM/SIRM, IRM_300mT/SIRM, IRM_? 300mT/SIRM and SIRM/χ_lf) were calculated. Potential sources of these lake sediments (catchment soils and dune materials close to the lake and in a distant sand plain) were sampled, and the magnetic properties of the surface-material specimens were measured. A chronological model was developed for An-S by comparing and combining AMS¹⁴C dates of An-S with ¹³⁷Cs, ²¹⁰Pb and AMS¹⁴C dates of An-A. With the help of surface-material magnetism, the magnetic data of An-S in combination with particle size, TOC and C/N and pollen analyses indicate the environmental changes during the last ～ 10,000 years around this lake. Conditions began to ameliorate at 10,900 cal. yr BP (9600 ¹⁴C yr BP) and thus relatively wet and warm environments prevailed during 10,900–8900 cal. yr BP (9600–8000 ¹⁴C yr BP). The Holocene optimum or the wettest and warmest conditions, was during 8900–7400 cal. yr BP (8000–6500 ¹⁴C yr BP). The environment began to deteriorate from 7400 cal. yr BP (6500 ¹⁴C yr BP) and the driest and coolest conditions occurred during 2200–480 cal. yr BP. There may have been a minor amelioration after 480 cal. yr BP. The inferred changes in palaeoenvironmental conditions around Anguli-nuur Lake are broadly in agreement with those around most other sites on the Inner Mongolia Plateau.     

Heat coma temperature,relative contents of saturated/unsaturated fatty acids and reproductive maturation in the oceanic sea skaters Halobates micans

This study was performed to clarify how the relative volume of saturated/unsaturated lipid and reproductive maturation relate to resistance to high temperature in the oceanic sea skaters, Halobates micans. Heat coma temperature (HCT) was measured in H. micans adults collected from a fixed sampling location (12°00′N, 135°00′E) in the western tropical Pacific Ocean. After measuring HCT, the specimen were dissected to measure the testes size and to determine the presence and number of oocytes in females. Bodies of the specimen were assessed by lipid analysis to evaluate saturated and unsaturated lipid content. A negative trend was seen between heat coma temperature and percentage of a saturated fatty acid, myristic acid (ratio of carbon number to number of double bonds = 14:0) (Pearson's correlation test: r = − 0.520, p = 0.101). In contrast, a positive trend was detected between heat coma temperature and percentage of an unsaturated fatty acid, palmitoleic acid (16:1) (r = 478, p = 0.137). Young males with small testes showed lower heat coma temperatures, whereas females that showed relatively high heat coma temperatures of 36–40 °C tended to have fewer mature oocytes in their ovaries than those that showed low heat coma temperatures of 30–34 °C. As Halobates appears to exhibit embryonic diapause rather than adult diapause, males of H. micans may develop both testes and resistance to high temperature in the parallel as they grow. In females, a trade-off may occur between heat tolerance function and oogenesis in the oceanic sea skaters.     

A reduced core to skin temperature gradient,not a critical core temperature,affects aerobic capacity in the heat

The purpose of this study was to determine the impact of the core to skin temperature gradient during incremental running to volitional fatigue across varying environmental conditions. A secondary aim was to determine if a “critical” core temperature would dictate volitional fatigue during running in the heat. 60 participants (n=49 male, n=11 female; 24±5 yrs, 177±11 cm, 75±13 kg) completed the study. Participants were uniformly stratified into a specific exercise temperature group (18 °C, 26 °C, 34 °C, or 42 °C) based on a 3-mile run performance. Participants were equipped with core and chest skin temperature sensors and a heart rate monitor, entered an environmental chamber (18 °C, 26 °C, 34 °C, or 42 °C), and rested in the seated position for 10 min before performing a walk/run to volitional exhaustion. Initial treadmill speed was 3.2 km h⁻¹ with a 0% grade. Every 3 min, starting with speed, speed and grade increased in an alternating pattern (speed increased by 0.805 km h⁻¹, grade increased by 0.5%). Time to volitional fatigue was longer for the 18 °C and 26 °C group compared to the 42 °C group, (58.1±9.3 and 62.6±6.5 min vs. 51.3±8.3 min, respectively, p<0.05). At the half-way point and finish, the core to skin gradient for the 18 °C and 26 °C groups was larger compared to 42 °C group (halfway: 2.6±0.7 and 2.0±0.6 vs. 1.3±0.5 for the 18 °C, 26 °C and 42 °C groups, respectively; finish: 3.3±0.7 and 3.5±1.1 vs. 2.1±0.9 for the 26 °C, 34 °C, and 42 °C groups, respectively, p<0.05). Sweat rate was lower in the 18 °C group compared to the 26 °C, 34 °C, and 42 °C groups, 3.6±1.3 vs. 7.2±3.0, 7.1±2.0, and 7.6±1.7 g m⁻² min⁻¹, respectively, p<0.05. There were no group differences in core temperature and heart rate response during the exercise trials. The current data demonstrate a 13% and 22% longer run time to exhaustion for the 18 °C and 26 °C group, respectively, compared to the 42 °C group despite no differences in beginning and ending core temperatures or baseline 3-mile run time. This capacity difference appears to result from a magnified core to skin gradient via an environmental temperature advantageous to convective heat loss, and in part from an increased sweat rate.     

Improved cryopreservation protocol for Blanca-Celtibérica buck semen collected by electroejaculation

The collection of sperm samples by electroejaculation (EE) leads to an increase of the production of seminal plasma which could modify the tolerance of spermatozoa to the cryopreservation procedure. This study aims to compare a standard sperm cryopreservation protocol for samples collected by artificial vagina (AV) with the same protocol and modifications to this for samples obtained by EE. Semen from six males of Blanca-Celtibérica goat breed was collected by AV (control) and EE, and three experiments were conducted. In Experiment 1, it was examined the effects of egg yolk concentration contained in freezing extender (0%, 1.5%, 10% and 20% of egg yolk); in Experiment 2, it was evaluated the cooling rate from 30 to 5 °C (fast: 10 min and slow: 90 min) and the temperature of glycerol addition (30 and 5 °C); and in Experiment 3, it was examined the time of equilibration at 5 °C (0, 1, 2 or 3 h). A heterologous in vitro fertilization test was carried out in order to compare the fertility of control samples with that resulting from the EE protocol which showed the highest sperm quality. Results showed greater sperm motility parameters after thawing for control samples cryopreserved in standard conditions in the three experiments. For samples collected by EE, extender with 20% egg yolk, a slow cooling rate and a longer equilibration time (3 h) provided higher sperm quality, and no differences were observed between temperatures of glycerol addition. Samples collected by EE and cryopreserved with the protocol which yielded the best sperm quality after thawing showed higher fertility compared to AV.     

Nitrate removal in surface-flow constructed wetlands treating dilute agricultural runoff in the lower Yakima Basin,Washington

Constructed treatment wetlands (CTWs) have been used effectively to treat a range of wastewaters and non-point sources contaminated with nitrogen (N). But documented long-term case studies of CTWs treating dilute nitrate-dominated agricultural runoff are limited. This study presents an analysis of four years of water quality data for a 1.6-ha surface-flow CTW treating irrigation return flows in Yakima Basin in central Washington. The CTW consisted of a sedimentation basin followed by two surface-flow wetlands in parallel, each with three cells. Inflow typically contained 1–3 mg-N/L nitrate and <0.4 mg-N/L total Kjeldahl N (TKN). Hydraulic loading was fairly constant, ranging from around 125 cm/d in the sedimentation basin to 12 cm/d in the treatment wetlands. Concentration removal efficiencies for nitrate averaged 34% in the sedimentation basin and 90–93% in the treatment wetlands. Total N removal efficiencies averaged 21% and 57–63% in the sedimentation basin and treatment wetlands, respectively. Area-based first-order removal rate constants for nitrate in the wetlands averaged 142–149 m/yr. Areal removal rates for nitrate in treatment wetlands averaged 139–146 mg-N/m²/d. Outflow from the CTW typically contained <0.1 mg-N/L nitrate and <0.6 mg-N/L TKN. Rates of nitrate loss in wetlands were highly seasonal, generally peaking in the summer months (June–August). Nitrate loss rates also correlated significantly with water temperature (positively) and dissolved oxygen (negatively). Based on the modified Arrhenius relationship, θ for nitrate loss in the wetlands was 1.05–1.09. The CTW also significantly affected temperature and dissolved oxygen concentration in waters flowing through the system. On average, the sedimentation basin caused an increase in temperature (+1.7 °C) and dissolved oxygen (+1.5 mg/L); in contrast the wetlands caused a decrease in temperature (?1.6 °C) and dissolved oxygen (?5.0 mg/L). Results show that CTWs with surface-flow wetlands can be extremely effective at polishing dilute non-point sources, particularly in semi-arid environments where warm temperatures and low oxygen levels in treatment wetland water promote biological denitrification.