Genomic constitution and taxonomy of the Chinese hexaploids Elymus cylindricus and E. breviaristatus (Poaceae: Triticeae)

Elymus cylindricus (2n = 6x = 42) and E. breviaristatus (2n = 6x = 42) are distributed in grasslands and deserts of northern and north‐western China. Their genomic constitution and taxonomic status are unclear. Elymus cylindricus was crossed with E. wawawaiensis J.R.Carlson & Barkworth ( StH ), Roegneria grandis Keng ( StY ) and Campeiostachys dahurica (Turcz. ex Griseb.) B.R.Baum, J.L. Y ang & C. Y en var. dahurica ( StYH ). Meiotic pairing in the hybrids E. cylindricus × E. wawawaiensis ( StH ), E. cylindricus × R. grandis ( StY ) and E. cylindricus × C. dahurica var. dahurica ( StYH ) showed on average 10.00, 11.30 and 20.92 bivalents per cell, respectively. Elymus breviaristatus was crossed with C. dahurica var. dahurica ( StYH ) and E. cylindricus. Chromosome pairing in the hybrids of E. breviaristatus × C. dahurica var. dahurica and E. breviaristatus × E. cylindricus showed on average 19.60 and 19.27 bivalents, respectively. Genomic in situ hybridization (GI SH ) revealed the presence of St , Y and H genomes in E. cylindricus and E. breviaristatus. An intergenomic rearrangement was observed in E. cylindricus using GI SH . Meiotic pairing data and GI SH indicated that both E. cylindricus and E. breviaristatus are allohexaploids containing the StYH genomes. Elymus cylindricus and E. breviaristatus should be treated as Campeiostachys dahurica var. cylindrica and Campeiostachys breviaristata, respectively.     

Comparative analysis of the digestive efficiency and nitrogen and energy requirements of the phyllostomid fruit-bat (Artibeus jamaicensis) and the pteropodid fruit-bat (Rousettus aegyptiacus)

Nitrogen (N) and energy (E) requirements of the phyllostomid fruit bat, Artibeus jamaicensis, and the pteropodid fruit bat Rousettus aegyptiacus, were measured in adults that were fed on four experimental diets. Mean daily food intake by A. jamaicensis and R. aegyptiacus ranged from 1.1–1.6 times body mass and 0.8–1.0 times body mass, respectively. Dry matter digestibility and metabolizable E coefficient were high (81.1% and 82.4%, respectively) for A. jamaicensis and (77.5% and 78.0%, respectively) for R. aegyptiacus. Across the four diets, bats maintained constant body mass with mean metabolizable E intakes ranging from 1357.3 kJ · kg^−0.75 · day⁻¹ to 1767.3 kJ · kg^−0.75 · day⁻¹ for A. jamaicensis and 1282.6–1545.2 kJ · kg^−0.75 · day⁻¹ for R. aegyptiacus. Maintenance E costs were high, in the order of 3.6–5.4 times the basal metabolic rate (BMR). It is unlikely that the E intakes that we observed represent a true measure of maintenance E requirements. All evidence seems to indicate that fruit bats are E maximizers, ingesting more E than required and regulating storage by adjusting metabolic output. We suggest that true maintenance E requirements are substantially lower than what we observed. If it follows the eutherian norm of two times the BMR, fruit bats must necessarily over-ingest E on low-N fruit diet. Dietary E content did affect N metabolism of A. jamaicensis. On respective low- and high-E diets, metabolic fecal N were 0.492 mg N · g⁻¹ and 0.756 mg N · g⁻¹ dry matter intake and endogenous urinary N losses were 163.31 mg N · kg^−0.75 · day⁻¹ and 71.54 mg N · kg^−0.75 · day⁻¹. A. jamaicensis required 332.3 mg · kg^−0.75 · day⁻¹ and 885.3 mg · kg^−0.75 · day⁻¹ of total N on high- and low-E diets, respectively, and 213.7 mg · kg^−0.75 · day⁻¹ of truly digestible N to achieve N balance. True N digestibilities were low (29% and 49%) for low- and high-E diets, respectively. For R. aegyptiacus, metabolic fecal N and endogenous urinary N losses were 1.27 mg N · g⁻¹ dry matter intake and 96.0 mg N · kg^−0.75 · day⁻¹, respectively, and bats required 529.8 mg · kg^−0.75 · day⁻¹ (total N) or 284.0 mg · kg^−0.75 · day⁻¹ (truly digestible N). True N digestibility was relatively low (50%). Based on direct comparison, we found no evidence that R. aegyptiacus exhibits a greater degree of specialization in digestive function and N retention than A. jamaicensis. When combined with results from previous studies, our results indicate that all fruit bats appear to be specialized in their ability to retain N when faced with low N diet. Accepted: 24 November 1998     

Structure of vegetation patches in northwestern Patagonia, Argentina

Vegetation of arid and semiarid environments has in general a patchy distribution. Our objective was to (a) determine several qualitative and quantitative analytical characteristics of vegetation patches in an arid zone of Patagonia, Argentina, and (b) investigate relationships between them. Annual precipitation in this area was 200 mm during 1999–2005. Eight transects involving ten patches each were studied within a 15 × 15 km area. Mean (±1 SE) values (n = 80) in the vegetation patches were 315 ± 25 and 207 ± 16 cm for the greatest and lowest patch diameter, respectively; 23 ± 2 cm for mound height; 113 ± 12 cm for maximum vegetation height; and 170 ± 18 cm and 58 ± 2% for distance to the next vegetation patch and vegetation patch cover within a transect, respectively. Correlations between greatest and lowest diameters, mound height, maximum plant height and distance to the closest vegetation patch were all significant (P < 0.01; n = 80). In all vegetation patches, the greatest and lowest frequencies were found for the grass Stipa spp. (71.2%) and the shrub Grindelia chiloensis (Cornel.) Cabrera (12.5%). Stipa spp. and the shrub Atriplex lampa (Moq.) D. Dietr. showed the highest simultaneous frequency (50%). A reasonable association among species (>45%) was found for Stipa spp., Atriplex lampa and the shrubs Larrea divaricata Cav., Lycium chilense Miers ex Bertero and Junellia ligustrina (Lag.) Moldenke. Larrea divaricata and Atriplex lampa contributed more than 84% of the total patch standing crop (5,777 ± 435 g). Average patch size and specific diversity were 5.93 ± 0.33 m² and 1.31 ± 0.11, respectively. Aboveground standing crop of the two dominant shrubs decreased as plant species diversity increased (P < 0.05). Conservation of vegetation patches is crucial to prevent increased soil erosion and desertification in the study ecological system.     

Identification of a 5-gene-based signature to predict prognosis and correlate immunomodulators for rectal cancer

BackgroundSpecific tumor markers have yet to be identified in rectal cancer. This study aims to identify a novel genetic signature in rectal cancer to provide clues for survival and immunotherapy.MethodsDEGs were obtained from two GEO datasets of rectal cancer. By using data from TCGA and GSE133057, two cohorts of rectal cancer were applied to establish and evaluate the signature. A nomogram was constructed for training and validation. We integrated the risk-score with clinicopathological features and assessed its interplay with immune cells and molecules. Finally, our study performed functional annotations, gene-targeted miRNAs, and single-cell analysis.ResultsA total of 468 DEGs were identified, and a signature consisting of 5 genes (CLIC5, ENTPD8, PACSIN3, HGD, and GNG7) was selected to calculate the risk-score. The model exhibited high performance in time-dependent ROC and a nomogram. Further results showed that overall survival was significantly worse in the high-risk group. As an independent prognostic factor, the risk-score was associated with vascular invasion. There was a dramatic difference in nonregulatory CD4⁺ and CD8⁺ T cells between the high and low-risk groups, and the 5 genes were correlated with immune inhibitors. There was a considerable difference in autophagy, immune, cell cycle, infection, and apoptosis-associated terms and pathways in GO and KEGG. The functional states of differentiation, apoptosis, and quiescence were closely related to the 5-gene signature in single-cell analysis.ConclusionOur results suggest that the signature could serve as a novel prognostic biomarker in rectal cancer, which might benefit decision-making regarding immunotherapy.     

Autotrophic and heterotrophic respiration in needle fir and Quercus-dominated stands in a cool-temperate forest, central Korea

To investigate annual variation in soil respiration (R _S) and its components [autotrophic (R _A) and heterotrophic (R _H)] in relation to seasonal changes in soil temperature (ST) and soil water content (SWC) in an Abies holophylla stand (stand A) and a Quercus-dominated stand (stand Q), we set up trenched plots and measured R _S, ST and SWC for 2 years. The mean annual rate of R _S was 436 mg CO₂ m⁻² h⁻¹, ranging from 76 to 1,170 mg CO₂ m⁻² h⁻¹, in stand A and 376 mg CO₂ m⁻² h⁻¹, ranging from 82 to 1,133 mg CO₂ m⁻² h⁻¹, in stand Q. A significant relationship between R _S and its components and ST was observed over the 2 years in both stands, whereas a significant correlation between R _A and SWC was detected only in stand Q. On average over the 2 years, R _A accounted for approximately 34% (range 17–67%) and 31% (15–82%) of the variation in R _S in stands A and Q, respectively. Our results suggested that vegetation type did not significantly affect the annual mean contributions of R _A or R _H, but did affect the pattern of seasonal change in the contribution of R _A to R _S.     

The genus Gymnetron from China with description of pre-imaginal stages of G. miyoshii,G. auliense and G. vittipenne (Coleoptera,Curculionidae)

There are four species of Gymnetron in China recorded to date including Gymnetron miyoshii Miyoshi, 1922, Gymnetron villosipenne Roelofs, 1875, Gymnetron auliense Reitter, 1907 and Gymnetron vittipenne Marseul, 1876, of which the last two are new country records. The pre-imaginal stages including eggs, mature larvae and pupae of Gymnetron miyoshii, Gymnetron auliense and Gymnetron vittipenne are described and illustrated. In addition, their diagnostic characters (larvae and pupae) are discussed and differentiated, and notes on some of their biological parameters are provided. Potential ecological impacts between Gymnetron weevils and their host Veronica spp. also are provided.     

Leptin and leptin receptor genetic variants associate with habitual physical activity and the arm body composition response to resistance training

Purpose

We investigated the influence of Leptin (LEP) and leptin receptor (LEPR) SNPs on habitual physical activity (PA) and body composition response to a unilateral, upper body resistance training (RT) program.

Methods

European-derived American volunteers (men = 111, women = 131, 23.4 ± 5.4 yr, 24.4 ± 4.6 kg·m^− 2) were genotyped for LEP 19 G>A (rs2167270), and LEPR 326 A>G (rs1137100), 668 A>G (rs1137101), 3057 G>A (rs1805096), and 1968 G>C (rs8179183). They completed the Paffenbarger PA Questionnaire. Arm muscle and subcutaneous fat volumes were measured before and after 12 wk of supervised RT with MRI. Multivariate and repeated measures ANCOVA tested differences among phenotypes by genotype and gender with age and body mass index as covariates.

Results

Adults with the LEP 19 GG genotype reported more kcal/wk in vigorous intensity PA (1273.3 ± 176.8, p = 0.017) and sports/recreation (1922.8 ± 226.0, p < 0.04) than A allele carriers (718.0 ± 147.2, 1328.6 ± 188.2, respectively). Those with the LEP 19 GG genotype spent more h/wk in light intensity PA (39.7 ± 1.6) than A allele carriers (35.0 ± 1.4, p = 0.03). In response to RT, adults with the LEPR 668 G allele gained greater arm muscle volume (67,687.05 ± 3186.7 vs. 52,321.87 ± 5125.05 mm³, p = 0.01) and subcutaneous fat volume (10,599.89 ± 3683.57 vs. − 5224.73 ± 5923.98 mm³, p = 0.02) than adults with the LEPR 668 AA genotype, respectively.

Conclusion

LEP19 G>A and LEPR 668 A>G associated with habitual PA and the body composition response to RT. These LEP and LEPR SNPs are located in coding exons likely influencing LEP and LEPR function. Further investigation is needed to confirm our findings and establish mechanisms for LEP and LEPR genotype and PA and body composition associations we observed.     

Serological evidence of Toxoplasma gondii and Neospora caninum infection in black-boned sheep and goats in southwest China

Toxoplasma gondii and Neospora caninum are two closely related protozoan parasites which can cause abortion and significant economic losses in sheep and goats. However, it is yet to know whether black-bone sheep and goats are infected with T. gondii and N. caninum in China. In the present investigation, the seroprevalence and risk factors of T. gondii and N. caninum infections in black-boned sheep and goats were investigated in Yunnan Province, subtropical southwest China between July and August of 2017. A total of 481 serum samples were tested for T. gondii antibodies using the Modified Agglutination Test (MAT), and 468 serum samples were examined for N. caninum antibodies by indirect Enzyme-Linked Immunosorbent Assay (iELISA). The overall seroprevalence of T. gondii in black-boned sheep and goats was 36.80% (177/481, 95% CI 32.49–41.11), and 40 out of 468 serum samples were N. caninum-seropositive (8.55%, 95% CI 6.02–11.08). There was significant difference in the seroprevalence of T. gondii infection in different regions (χ² = 19.869, df = 2, P<0.01). As for the seroprevalence of N. caninum infection, region (χ² = 8.558, df = 2, P<0.05), age (χ² = 16.631, df = 3, P < 0.01), gender (χ² = 11.219, df = 1, P < 0.01) and species (χ² = 8.673, df = 1, P < 0.01) were the risk factors. In addition, the seroprevalence of coinfection of T. gondii and N. caninum in black-boned sheep and goats was 3.63% (17/468, 95% CI 1.94–5.32). To our knowledge, this is the first report of T. gondii and N. caninum seroprevalence in black-boned sheep and goats in China, which provided base-line data for the execution of control strategies and measures against T. gondii and N. caninum infection in black-boned sheep and goats.     

Dynamics of gaseous nitrogen and carbon fluxes in riparian alder forests

We studied greenhouse gas (GHG) fluxes in two differently loaded riparian Alnus incana-dominated forests in agricultural landscapes of southern Estonia: a 33-year-old stand in Porijõgi, in which the uphill agricultural activities had been abandoned since the middle of the 1990s, and a 50-year-old stand in Viiratsi, which still receives polluted lateral flow from uphill fields fertilized with pig slurry. In Porijõgi, closed-chamber based sampling lasted from October 2001 to October 2009, whereas in Viiratsi the sampling period was from November 2003 to October 2009. Both temporal and spatial variations in all GHG gas fluxes were remarkable. Local differences in GHG fluxes between micro-sites (“Edge”, “Dry” and “Wet” in Porijõgi, and “Wet”, “Slope” and “Dry” in Viiratsi) were sometimes greater than those between sites. Median values of GHG fluxes from both sites over the whole study period and all microsites did not differ significantly, being 45 and 42 mg CO₂-C m⁻² h⁻¹, 8 and 0.5 μg CH₄-C m⁻² h⁻¹, 1.0 and 2.1 mg N₂-N m⁻² h⁻¹, and 5 and 9 μg N₂O-N m⁻² h⁻¹, in Porijõgi and Viiratsi, respectively. The N₂:N₂O ratio in Viiratsi (40-1200) was lower than in Porijõgi (10-7600). The median values-based estimation of the Global Warming Potential of CH₄ and N₂O was 19 and 185 kg CO₂ equivalents (eq) ha⁻¹ yr⁻¹ in Porijõgi and −14 and 336 kg CO₂ eq ha⁻¹ yr⁻¹ in Viiratsi, respectively. A significant Spearman rank correlation was found between the mean monthly air temperature and CO₂, CH₄ and N₂ fluxes in Porijõgi, and N₂O flux in Viiratsi, and between the monthly precipitation and CH₄ fluxes in both study sites. Higher groundwater level significantly increases CH₄ emission and decreases CO₂ and N₂O emission, whereas higher soil temperature significantly increases N₂O, CH₄ and N₂ emission values. In Porijõgi, GHG emissions did not display any discernable trend, whereas in Viiratsi a significant increase in CO₂, N₂, and N₂O emissions has been found. This may be a result of the age of the grey alder stand, but may also be caused by the long-term nutrient load of this riparian alder stand, which indicates a need for the management of similar heavily loaded riparian alder stands.     

Diffusion and sedimentation interaction parameters for measuring the second virial coefficient and their utility as predictors of protein aggregation

The concentration-dependence of the diffusion and sedimentation coefficients (k_D and k_s, respectively) of a protein can be used to determine the second virial coefficient (B₂), a parameter valuable in predicting protein-protein interactions. Accurate measurement of B₂ under physiologically and pharmaceutically relevant conditions, however, requires independent measurement of k_D and k_s via orthogonal techniques. We demonstrate this by utilizing sedimentation velocity (SV) and dynamic light scattering (DLS) to analyze solutions of hen-egg white lysozyme (HEWL) and a monoclonal antibody (mAb1) in different salt solutions. The accuracy of the SV-DLS method was established by comparing measured and literature B₂ values for HEWL. In contrast to the assumptions necessary for determining k_D and k_s via SV alone, k_D and ks were of comparable magnitudes, and solution conditions were noted for both HEWL and mAb1 under which 1), k_D and k_s assumed opposite signs; and 2), k_D ≥ k_s. Further, we demonstrate the utility of k_D and k_s as qualitative predictors of protein aggregation through agitation and accelerated stability studies. Aggregation of mAb1 correlated well with B₂, k_D, and k_s, thus establishing the potential for k_D to serve as a high-throughput predictor of protein aggregation.     

Plasma paraoxonase-1, oxidized low-density lipoprotein and lipid peroxidation levels in gout patients

Gout patients have a high incidence of atherosclerotic coronary heart disease. Low serum paraoxonase (PON) activity is considered a risk factor for atherosclerosis. The relationships among paraoxonase-1 (PON1) activity, oxidative stress parameters, and atherosclerosis in gout is not known. Therefore, we determined the plasma levels of malondialdehyde (MDA), oxidized low-density lipoprotein (Ox-LDL), and activities of PON1/superoxide dismutase (SOD) activities in 49 gout patients (mean age 44.2 ± 7.0 years) and 42 healthy, age-matched controls (mean age 45.0 ± 9.3 years). PON1 was measured spectrophotometrically, MDA by thiobarbituric acid method, SOD by Griess reaction, and Ox-LDL by sandwich ELISA. Lipid and other biochemical parameters were determined by routine laboratory methods. In gout patients, PON1/SOD activities and MDA/Ox-LDL levels were 131.3 ± 25.3/75.3 ± 28.9 kU l⁻¹ and 6.12 ± 1.67 nmol ml⁻¹/690.1 ± 180.2 μg l⁻¹, respectively. In controls, these were 172.5 ± 27.8/94.0 ± 26.3 kU l⁻¹ and 4.10 ± 1.25 nmol ml⁻¹/452.3 ± 152.1 μg l⁻¹, respectively. Thus, in gout patients, there was a significant decrease in PON1 (P < 0.01) and SOD (P < 0.05) activities, and an increase in MDA (P < 0.01) and Ox-LDL (P < 0.01) levels compared with controls. PON1 activity correlated positively with SOD (P < 0.05), and negatively with MDA (P < 0.01) and Ox-LDL (P < 0.01). These results suggest that gout patients were in a state of oxidative stress and the protective effects of HDL against atherosclerosis maybe dependent on PON1 activity. These findings may explain in part the reported increase in cardiovascular mortality in gout patients.     

Circulatory function at sub-zero temperature: venous responses to catecholamines and angiotensin II in the Antarctic fish <Emphasis Type="Italic">Pagothenia borchgrevinki</Emphasis>

Catecholamines increase arterial pressure by increasing cardiac output (Q) and stroke volume (V _s), while angiotensin II (ang II) also increases vascular resistance (R _sys) in the Antarctic fish Pagothenia borchgrevinki. Adrenaline, phenylephrine and ang II (Asn¹, Val⁵) were injected into P. borchgrevinki. Cardiovascular variables, including central venous pressure (P _cv) and mean circulatory filling pressure (P _mcf; an index of venous capacitance), were recorded to investigate if venous vasoconstriction can explain the increased V _s and Q and the arterial pressor response in this species. Routine P _cv and P _mcf were 0.11 ± 0.01 and 0.18 ± 0.02 kPa, respectively. All of the drugs caused moderate increases in P _cv and P _mcf and the responses were attenuated after α-adrenergic blockade with prazosin. Although dorsal aortic pressure (P _da) also increased in response to all agonists, the mechanisms differed. Adrenaline caused sustained increases in V _s and Q, while R _sys only rose transiently. Ang II had a slower effect than adrenaline and increased both R _sys and Q, while phenylephrine only increased R _sys. This study demonstrates that P _cv is positive and controlled by an α-adrenergic mechanism in P. borchgrevinki. However, given the relatively small venous response to adrenaline it seems more likely that the increases in V _s and Q from this agonist are due to direct effects on the heart.     

Oxidative stress elevated DNA damage and homocysteine level in normal pregnant women in a segment of Pakistani population

Maternal oxidative stress during pregnancy may impair fetal growth and help in the development of diseases in adulthood. The aim of current study was to assess total oxidation status (TOS), related parameters and their relationship to DNA damage (%) and homocysteine level in normal pregnant women in low-income participants. In a cross-sectional study healthy women were grouped as normal, while age matched nulliparous and singleton pregnancies were included for first, second and third trimester groups. TOS (P < 0.01), melanodialdehyde (MDA) (P < 0.001), aspartate aminotransferase (AST) (P < 0.01), triiodothyronine (T3) (P < 0.01), thyroxine (T4) (P < 0.01), and homocysteine (P < 0.001), in pregnant women were significantly higher as compared to normal healthy women. While serum total proteins (P < 0.01), albumin (P < 0.01) and total antioxidant status (TAS) (P < 0.001) decreased significantly as compared to normal healthy women. Women in third trimester showed a significantly high level of body temperature (P < 0.01), triglyceride (P < 0.01), LDL-cholesterol (P < 0.05), AST (P < 0.01), T3 (P < 0.01), homocysteine (P < 0.001), TOS (P < 0.01) and MDA (P < 0.001) but a lower concentration of serum proteins, albumin and TAS at the end of the pregnancy. Pearson correlation indicated a positive relationship of homocysteine with triglycerides (P < 0.027), TOS (P < 0.01), MDA (P < 0.035) and had a negative relationship with total protein (P < 0.026). DNA damage was strongly related with T3 (P < 0.008), TOS (P < 0.02), MDA (P < 0.037) and MBI (P < 0.048) profiles of pregnant women. These changes were considered normal for pregnant women having optimum blood pressure and normal child birth. Hormonal influences and hemodilution may contribute towards the observed changes in this study.     

Foraminiferal ecological zonation along a Brazilian mangrove transect: Diversity, morphotypes and the influence of subaerial exposure time

Two foraminiferal associations comprising only arenaceous species define two distinct environments in a 340 m-long mangrove transect at Cardoso Island, Trapandé Bay (Cananéia-Iguape estuarine system, SP, Brazil). The “lower muddy flat” (LMF), from the outer mangrove fringe inwards towards land (100 m), is positioned in the lower plain between 0.04 and 0.23 m above the mean sea level (msl), and remains subaerially exposed between 48.5 and 65.6% of the time. This environment is characterized by higher foraminiferal diversity and evenness (McIntosh's D = 0.54 ± 0.21 and Pielou's E = 0.68 ± 0.25, respectively) and is dominated by Arenoparrella mexicana and Trochammina inflata, and to a lesser extent by Ammotium directum and Textularia earlandi. The mangrove plant of this segment is a Rhizophoretum with average height of 8.4 ± 1.2 m. The sediment is characterized by higher concentration of organic matter (93.5 ± 32.3 g dm⁻³) and metals (e.g. V = 53.4 ± 21.8 ppm and Zn = 46.4 ± 21.3 ppm). The “upper sandy flat” (USF), 240 m wide along the transect, is positioned in the upper plain between 0.28 and 0.89 m above the msl, and remains subaerially exposed between 69.7 and 98.5% of the time. This environment is characterized by a lower diversity and evenness (D = 0.33 ± 0.17 and E = 0.49 ± 0.20, respectively). The association is dominated by species T. inflata and Miliammina fusca. The Rhizophoretum exhibits a lower average height of 3.6 ± 0.6 m. The sediment is poorer in organic matter (39.3 ± 15.0 g dm⁻³) and metals (e.g. V = 13.0 ± 6.8 ppm and Zn = 6.9 ± 3.7 ppm). Whereas “elongate” tests (uniserial, biserial and planospiral followed by a uniserial portion) are restricted to the LMF, “spiraled” species dominate the USF. Subaerial exposure time seems to exert a primary influence on species distribution, in addition to salinity and sediment type. Species may be adapted to different exposure times, a factor dependent on their position on the intertidal zone and the tidal regime, which should be taken into account in relative sea level reconstructions based on intertidal foraminifera. These patterns have important implications for studies investigating the ecology and paleoecology of foraminifera and subtle fluctuations in relative sea level during the Quaternary.     

Compensatory effects of elevated CO<Subscript>2</Subscript> concentration on the inhibitory effects of high temperature and irradiance on photosynthetic gas exchange in carrots

We determined the interactive effects of irradiance, elevated CO₂ concentration (EC), and temperature in carrot (Daucus carota var. sativus). Plants of the cv. Red Core Chantenay (RCC) were grown in a controlled environmental plant growth room and exposed to 3 levels of photosynthetically active radiation (PAR) (400, 800, 1 200 μmol m⁻² s⁻¹), 3 leaf chamber temperatures (15, 20, 30 °C), and 2 external CO₂ concentrations (C _a), AC and EC (350 and 750 μmol mol⁻¹, respectively). Rates of net photosynthesis (P _N) and transpiration (E) and stomatal conductance (g _s ) were measured, along with water use efficiency (WUE) and ratio of internal and external CO₂ concentrations (C _i/C _a). P _N revealed an interactive effect between PAR and C _a. As PAR increased so did P _N under both C _a regimes. The g _s showed no interactive effects between the three parameters but had singular effects of temperature and PAR. E was strongly influenced by the combination of PAR and temperature. WUE was interactively affected by all three parameters. Maximum WUE occurred at 15 °C and 1 200 μmol m⁻² s^{− 1} PAR under EC. The C _i /C _a was influenced independently by temperature and C _a. Hence photosynthetic responses are interactively affected by changes in irradiance, external CO₂ concentration, and temperature. EC significantly compensates the inhibitory effects of high temperature and irradiance on P _N and WUE.     

Muscle quality. II. Effects of strength training in 65-to 75-yr-old men and women

To determine theeffects of strength training (ST) on muscle quality (MQ,strength/muscle volume of the trained muscle group), 12 healthy oldermen (69 ± 3 yr, range 65-75 yr) and 11 healthy older women (68 ± 3 yr, range 65-73 yr) were studied before and after aunilateral leg ST program. After a warm-up set, four sets ofheavy-resistance knee extensor ST exercise were performed 3 days/wk for9 wk on the Keiser K-300 leg extension machine. The men exhibitedgreater absolute increases in the knee extension one-repetition maximum(1-RM) strength test (75 ± 2 and 94 ± 3 kg before andafter training, respectively) and in quadriceps muscle volume measuredby magnetic resonance imaging (1,753 ± 44 and 1,955 ± 43 cm³) than the women (42 ± 2 and 55 ± 3 kg for the 1-RM test and 1,125 ± 53 vs.1,261 ± 65 cm³ forquadriceps muscle volume before and after training, respectively, inwomen; both P < 0.05). However,percent increases were similar for men and women in the 1-RM test (27 and 29% for men and women, respectively), muscle volume (12% forboth), and MQ (14 and 16% for men and women, respectively).Significant increases in MQ were observed in both groups in the trainedleg (both P < 0.05) and in the 1-RMtest for the untrained leg (both P < 0.05), but no significant differences were observed between groups,suggesting neuromuscular adaptations in both gender groups. Thus,although older men appear to have a greater capacity for absolutestrength and muscle mass gains than older women in response to ST, the relative contribution of neuromuscular and hypertrophic factors to theincrease in strength appears to be similar between genders.

     

Effect of temperature on biological characteristics and life table parameters of Dicrodiplosis manihoti Harris on cotton mealybug,Phenacoccus solenopsis Tinsley

The cotton mealybug Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae) is one of the polyphagous and destructive pests in the world. It has caused a lot of damage in cotton fields and settles on other host plants, especially Chinese hibiscus shrubs Hibiscus rosa-sinensis L. and causes irrecoverable damages to these ornamental plants and urban landscape. Midge fly Dicrodiplosis manihoti Harris (Dip.: Cecidomiidae) is one of the most common fly species which was collected in mealybugs colonies. In this study, the biology and age-stage, two-sex life table parameters of Dicrodiplosis manihoti, was evaluated at four constant temperatures (22, 27, 32 and 37 ± 1 °C, 65 ± 5 % RH and a photoperiod of 16: 8 (L: D) h) in the laboratory conditions. The developmental pre-adult period was found as 36.12 ± 0.38, 24.09 ± 0.41, 14.96 ± 0.34 and 12.68 ± 0.26 days and the average egg produced by females was 23.65 ± 2.86, 11.14 ± 2.09, 12.32 ± 3.94 and 8.57 ± 0.67 at those temperatures, respectively which decreased as the temperature increased from 22 to 37 °C, respectively. The population intrinsic rate of increase (r_m) was 0.0247 ± 0.0051, 0.0291 ± 0.0099, 0.0374 ± 0.0206 and 0.0103 ± 0.0129 (d^-1), and the population finite rate of increase (λ) for the above mentioned temperatures was 1.0249 ± 0.0052, 1.0295 ± 0.0101, 1.0384 ± 0.0212 and 1.0104 ± 0.0130 (d^-1), respectively. Also, the net reproductive rate (R₀) at the above mentioned temperatures was 2.62 ± 0.5, 2.19 ± 0.53, 2.05 ± 0.73 and 1.18 ± 0.22 offspring respectively. The shortest (T = 14.88 ± 0.45 days) and the longest (T = 38.28 ± 0.65 days) mean generation time was recorded at 37 and 22 °C, respectively. According to the results of this study D. manihoti has a good potential to control of Ph. solenopsis and the temperature of around 32 °C is the best for mass rearing this predator.     

Correspondence of environmental tolerances with leaf and branch attributes for six co-occurring species of broadleaf evergreen trees in northern California

 For the angiosperm dominants of northern California’s mixed evergreen forests, this study compares the display of photosynthetic tissue within leaves and along branches, and examines the correspondence between these morphological attributes and the known environmental tolerances of these species. Measurements were made on both sun and shade saplings of six species: Arbutus m e n z i e s i i (Ericaceae), C h r y s o l e p i s c h r y s o p h y l l a (Fagaceae), L i t h o c a r p u s d e n s i f l o r u s (Fagaceae), Quercus c h r y s o l e p i s (Fagaceae), Quercus w i s l i z e n i i (Fagaceae), and Umbellularia c a l i f o r n i c a (Lauraceae). All species had sclerophyllous leaves with thick epidermal walls, but species differed in leaf specific weight, thickness of mesophyll tissues and in the presence of a hypodermis, crystals, secretory idioblasts, epicuticular deposits, and trichomes. The leaves of Arbutus were 2 – 5 times larger than those of C h r y s o l e p i s, L i t h o c a r p u s and Umbellularia and 4 – 10 times larger than those of both Quercus species. Together with differences in branch architecture, these leaf traits divide the species into groups corresponding to environmental tolerances. Shade-tolerant C h r y s o l e p i s, L i t h o c a r p u s, and Umbellularia had longer leaf lifespans and less palisade tissue, leaf area, and crown mass per volume than the intermediate to intolerant Arbutus and Quercus. Having smaller leaves, Quercus branches had more branch mass per leaf area and per palisade volume than other species, whereas Arbutus had less than other species. These differences in display of photosynthetic tissue should contribute to greater growth for Quercus relative to the other species under high light and limited water, for Arbutus under high light and water availability, and for C h r y s o l e p i s, L i t h o c a r p u s, and Umbellularia under limiting light levels. Accepted: 22 March 1996     

沙质草地3种优势植物叶片光合生理对增温和降水减少的响应北大核心CSCD

以沙质草地优势物种猪毛蒿、胡枝子和糙隐子草为研究对象,利用开顶式生长室(OTC)模拟增温,研究降水减少20%、40%和60%与增温的交互作用对3种典型植物叶片光合气体交换特征及叶绿素荧光特征的影响,以揭示沙质草地3种优势植物对气候变化的响应规律。结果显示:(1)与自然温度相比,OTC模拟增温增加了猪毛蒿C_(i),显著降低了胡枝子G_(s)、P_(n)和T_(r)、糙隐子草G_(s)和P_(n)、猪毛蒿WUE和L_(s),也显著降低了猪毛蒿和胡枝子F_(v)/F_(m)和F_(v)/F_(o)。(2)无论增温与否,随着降水减少幅度的增加,猪毛蒿G_(s)和P_(n)呈下降趋势,且中度以上的干旱胁迫下(降水减少>40%)胡枝子和糙隐子草P_(n)显著低于对照。(3)在自然温度条件下,轻度干旱胁迫时(降水减少20%)猪毛蒿T_(r)显著低于对照,重度干旱胁迫时(降水减少60%)其WUE、F_(v)/F_(m)和F_(v)/F_(o)显著低于对照;重度干旱胁迫时,胡枝子C_(i)显著高于对照,差异幅度达10.7%,L_(s)显著低于对照,轻度干旱胁迫时(降水减少20%)其F_(v)/F_(m)和F_(v)/F_(o)显著高于中度以上的干旱胁迫;中度以上的干旱胁迫下糙隐子草T_(r)和G_(s)显著低于对照,重度干旱胁迫时,其C_(i)、F_(v)/F_(m)和F_(v)/F_(o)显著低于对照,WUE和L_(s)显著高于对照。(4)增温与降水减少交互作用下,所有处理猪毛蒿C_(i)均高于对照,差异幅度分别达4.5%,6.0%和8.4%;胡枝子T_(r)均显著低于对照,差异幅度达57.8%;重度干旱胁迫时猪毛蒿L_(s)和WUE显著低于对照,糙隐子草F_(v)/F_(m)和F_(v)/F_(o)随降水减少而降低,中度以上的干旱胁迫时其值显著低于对照。(5)相关性分析表明,3个优势物种的P_(n)与F_(v)/F_(m)和F_(v)/F_(o)均呈显著正相关关系,其中猪毛蒿和糙隐子草的P_(n)—F_(v)/F_(m)和P_(n)—F_(v)/F_(o)斜率明显高于胡枝子。研究表明,气候变暖会在一定程度上加剧降水减少对沙质草地3种群落优势物种光合作用的抑制。