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1.
Abstract Broadscale habitat use by Eastern Curlews (Numenius madagascariensis) in their non‐breeding range in eastern Australia was assessed using low tide surveys on feeding grounds, where 60 skilled volunteers made repeated counts of the birds on intertidal flats, across 41% (9500 ha) of the intertidal habitat within Moreton Bay, Australia. We analysed 32 defined sections of intertidal flat, of roughly equal area (mostly 200–400 ha), which varied greatly in their curlew density (2–47 birds per 100 ha) and also in substrate and other environmental features. Sites with the least resistant substrates had densities three times those with the most resistant substrates. Of 10 environmental characteristics measured for each site, substrate resistance was the best predictor of curlew density (r2 = 0.45). Characteristics that were poor predictors included distance to the nearest roost, level of human disturbance and distance to urban settlement. For a finer‐scale assessment, microhabitat use and feeding behaviour were recorded during low tide within 12 intertidal flats, which varied in size (23–97 ha), substrate, topography and other features. Across all flats, curlews strongly preferred to feed relatively close (0–50 m) to the low‐water line. They fed on a variety of substrates (including sand, sandy‐mud, mud and seagrass) in broadly similar proportions to their occurrence in the habitat. There was a statistically significant preference for sand, although its magnitude was not strong. These results indicate that curlews select habitat most strongly at a between‐flat rather than within‐flat scale.  相似文献   

2.
To determine if anthropogenically modified habitats possess greater numbers of round goby and serve as dispersal vectors, we used angling to compare catch‐per‐unit of effort for 64 natural and modified habitat areas. In addition, a gravel natural habitat was seined to compare length frequency distribution with anthropogenically modified habitats. Natural habitats included gravel beaches and natural rubble and cliff wall, while modified habitats included artificial riprap, concrete sea wall, and metal sheet piling. No significant difference in relative abundance was observed in round goby preference among modified habitats (P = 0.52), but natural gravel habitats were significantly different from modified habitats that included artificial riprap (P = 0.002), concrete sea wall (P < 0.001), and metal sheet piling (P = 0.003). When habitat subcategories were compared using anova , the natural gravel beach habitat was significantly different from the three artificial substrates and from natural rubble and cliff wall substrates (P < 0.004). No round goby were caught from gravel beach habitats; thus, this habitat was removed from further analysis. A Student t‐test indicated no significant difference between habitats was found between the natural rubble and cliff wall habitat and the three other artificial habitats (concrete sea wall, P = 0.33; riprap, P = 0.53; metal sheet piling, P = 0.11). We further evaluated gravel beach habitats to determine the reason for the lack of goby capture. We seined gravel beach habitat and collected 328 individuals, with which we evaluated the length‐frequency distribution and calculated length–weight relationships by sex. Our results indicated that only 5.2% of the goby population was available for capture by angling on the gravel beach habitat. A t‐test comparing the demographic attributes between seining and angling indicated a significant difference between goby length (P < 0.001) and weight (P < 0.001). The regression slope indicated an ontogenetic habitat shift occurred near 62 mm standard length. Smaller round goby individuals were found in less structurally complex gravel beach habitat, while larger individuals were associated with complex habitat.  相似文献   

3.
Distribution and density by habitat for age‐0, young‐of‐the‐year (YOY) winter flounder, Pseudopleuronectes americanus (Walbaum, 1792), were compared for two Maine estuaries to help define essential fish habitat for this life history stage. Two estuaries (Weskeag River and Penobscot Bay) along Mid‐coast Maine were sampled monthly with daytime 1.0 m2 fixed‐frame throw traps around neap low tide, May–December over two consecutive years (2003–2004). Both eelgrass and adjacent sand/mud (20–60 cm deep) were randomly sampled with equal effort (4–12 samples per month) at two sites in both the Weskeag River and Penobscot Bay. Significantly higher densities of YOY winter flounder (2–9 cm TL) occurred in eelgrass relative to sand/mud. Density increased significantly in both habitats in 2004, and was higher in Penobscot Bay relative to the Weskeag River. YOY densities compared by eelgrass coverage within throw traps were found to be significantly higher in eelgrass that exceeded 30% coverage when compared with adjacent sand/mud areas and eelgrass coverage of 10–20%. YOY occurred in all months sampled (May–December); no density differences existed by month. These results indicate that very shallow (<0.6 m) eelgrass habitat is of key importance to YOY winter flounder in Maine estuaries and should be viewed as essential fish habitat (EFH) for this species and life stage.  相似文献   

4.
Abstract. The thermal preferences of Alaskozetes antarcticus (Acari, Cryptostigmata) and Cryptopygus antarcticus (Collembola, Isotomidae) were investigated over 6 h within a temperature gradient (?3 to +13 °C), under 100% relative humidity (RH) conditions. After 10 days of acclimation at ?2 or +11 °C, individual supercooling points (SCP) and thermopreferences were assessed, and compared with animals maintained for 10 days under fluctuating field conditions (?6 to +7 °C). Acclimation at ?2 °C lowered the mean SCP of both A. antarcticus (?24.2 ± 9.1) and C. antarcticus (?14.7 ± 7.7) compared to field samples (?19.0 ± 9.0 and ?10.7 ± 5.2, respectively). Acclimation at +11 °C increased A. antarcticus mean SCP values (?13.0 ± 8.5) relative to field samples, whereas those of C. antarcticus again decreased (?16.7 ± 9.1). Mites acclimated under field conditions or at +11 °C selected temperatures between ?3 and +1 °C. After acclimation at ?2 °C, both species preferred +1 to +5 °C. Cryptopygus antarcticus maintained under field conditions preferred +5 to +9 °C, whereas individuals acclimated at +11 °C selected +9 to +13 °C. For A. antarcticus, thermopreference was not influenced by its cold hardened state. The distribution of field specimens was further assessed within two combined temperature and humidity gradient systems: (i) 0–3 °C/12% RH, 3–6 °C/33% RH, 6–9 °C/75% RH and 9–12 °C/100% RH and (ii) 0–3 °C/100% RH, 3–6 °C/75% RH, 6–9 °C/33% RH and 9–12 °C/12% RH. In gradient (i), C. antarcticus distributed homogeneously, but, in gradient (ii), C. antarcticus preferred 0–3 °C/100% RH. Alaskozetes antarcticus selected temperatures between 0 and +6 °C regardless of RH conditions. Cryptopygus antarcticus appears better able than A. antarcticus to opportunistically utilize developmentally favourable thermal microclimates, when moisture availability is not restricted. The distribution of A. antarcticus appears more influenced by temperature, especially during regular freeze‐thaw transitions, when this species may select low temperature microhabitats to maintain a cold‐hardened state.  相似文献   

5.
Escherichia coli ClpB is a molecular chaperone that belongs to the Clp/Hsp100 family of AAA+ proteins. ClpB is able to form a hexameric ring structure to catalyze protein disaggregation with the assistance of the DnaK chaperone system. Our knowledge of the mechanism of how ClpB recognizes its substrates is still limited. In this study, we have quantitatively investigated ClpB binding to a number of unstructured polypeptides using steady‐state anisotropy titrations. To precisely determine the binding affinity for the interaction between ClpB hexamers and polypeptide substrates the titration data were subjected to global non‐linear least squares analysis incorporating the dynamic equilibrium of ClpB assembly. Our results show that ClpB hexamers bind tightly to unstructured polypeptides with binding affinities in the range of ~3–16 nM. ClpB exhibits a modest preference of binding to Peptide B1 with a binding affinity of (1.7 ± 0.2) nM. Interestingly, we found that ClpB binds to an unstructured polypeptide substrate of 40 and 50 amino acids containing the SsrA sequence at the C‐terminus with an affinity of (12 ± 3) nM and (4 ± 2) nM, respectively. Whereas, ClpB binds the 11‐amino acid SsrA sequence with an affinity of (140 ± 20) nM, which is significantly weaker than other polypeptide substrates that we tested here. We hypothesize that ClpB, like ClpA, requires substrates with a minimum length for optimal binding. Finally, we present evidence showing that multiple ClpB hexamers are involved in binding to polypeptides ≥152 amino acids. Proteins 2015; 83:117–134. © 2014 Wiley Periodicals, Inc.  相似文献   

6.
The present study attempts to assess the potential of artificial substrates to enhance fish production in inland saline groundwater ponds through periphyton production. Grey mullet, Mugil cephalus, was cultured for 100 days in ponds with substrate (treatment ponds) and without substrate (control ponds). To enhance the surface area, bamboo poles were used as substrate. The periphyton population, pigment concentration and hydrobiological characteristics of pond water were monitored. The studies revealed little difference in most of the water quality parameters observed in the two treatments. However, turbidity (27.0 ± 0.1–35.0 ± 0.1 Nephalo Turbidity Unit (NTU)), chlorophyll ‘a’ (6.6 ± 0.6–7.6 ± 0.6 μg L?1), plankton population (phytoplankton 8.4 × 103–9.4 ×103 numbers L?1; zooplankton 4.0 × 103–5.1 × 103 numbers L?1) and NH4–N (2.0 ± 0.2–2.3 ± 0.1 mg L?1) were high in the treatment with no additional substrate; however, in the treatment with substrate the total Kjeldahl nitrogen (9.8 ± 0.8–10.8 ± 0.7 mg L?1) and o‐PO4 (0.1 ± 0.01–0.1 mg L?1) remained significantly (P < 0.05) higher. Highest periphyton biomass in terms of dry matter (DM) (0.8 ± 0.01–1.4 ±0.01 mg cm?2), ash free DM (0.4 ± 0.0–0.6 ± 0.01 mg cm?2), chlorophyll ‘a’ (3.1 ± 0.2–8.1 ± 0.8 μg cm?2) and pheophytin ‘a’ (1.9 ± 0.4–3.9 ± 0.5 μg cm?2) was observed at 50 cm depth in ponds provided with additional substrate. Fifteen plankton genera showing periphytic affinity colonized the bamboo substrates. Fish growth (mean fish weight 524.3 ± 8.7 g and SGR 2.5 ± 0.1) was significantly (P < 0.05) higher in ponds provided with additional substrate compared with control ponds (387.2 ± 6.0). Length–weight relationship (LWR) (W = cLn) also showed that the exponential value (‘n’) of length was high in substrate‐supported ponds (n = 2.36) in comparison with controls (n = 1.09). These studies suggest that a periphyton‐supported aquaculture system can be used successfully for the culture of herbivorous brackishwater fish species like M. cephalus in inland saline groundwaters and thus could contribute to the development of sound and sustainable aquaculture technology.  相似文献   

7.
Removal of polychlorinated biphenyls (PCBs) from contaminated sediments is a priority due to accumulation in the food chain. Recent success with reduction of PCB bioavailability due to adsorption onto activated carbon led to the recognition of in situ treatment as a remediation approach. In this study, reduced bioavailability and subsequent break-down of PCBs in dehalorespiring biofilms was investigated using Dehalobium chlorocoercia DF1. DF1 formed a patchy biofilm ranging in thickness from 3.9 to 6.7?µm (average 4.6?±?0.87?µm), while the biofilm coverage varied from 5.5% (sand) to 20.2% (activated carbon), indicating a preference for sorptive materials. Quantification of DF1 biofilm bacteria showed 1.2–15.3?×?109 bacteria per gram of material. After 22?days, coal activated carbon, bone biochar, polyoxymethylene, and sand microcosms had dechlorinated 73%, 93%, 100%, and 83%, respectively. These results show that a biofilm-based inoculum for bioaugmentation of PCBs in sediment can be an efficient approach.  相似文献   

8.
Reconciliation has been demonstrated in all primate species in which the phenomenon has been studied. However, reconciliation has been studied in only two species of callitrichids, and conclusions remain controversial. The first aim of this study has been to find out whether captive cotton‐top tamarins (Saguinus oedipus) reconcile, since this is the first such study on this species. We examined 227 conflicts in three family groups (N=19). Instances in which individuals remained together in t=0 (29; 12.8%) were not analyzed. The cotton‐top tamarins showed heightened affiliation between opponents in the postconflict periods (PC) compared with matched control (MC) periods (39.88±5.12% and 3.18±1.27%, respectively), with a corrected conciliatory tendency of 37.17±5.37%, and a “time window” that included the first 180 sec of the PC period. Former opponents were the most likely recipient of affiliative behaviors during the PC periods: 39.83±4.26% vs. 11.36±5.33% during MC periods. The proportion of attracted pairs (47.13±6.25%) was significantly higher than those of dispersed pairs for male–male conflicts (3.79±1.79), but not for male–female conflicts (27.31±9.32 and 4.82±2.9, respectively). In cooperative‐breeding species, specific sex‐class dyads might differ in how they resolve conflicts. Am. J. Primatol. 71:895–900, 2009. © 2009 Wiley‐Liss, Inc.  相似文献   

9.
1. The effects of habitat isolation, persistence, and host‐plant structure on the incidence of dispersal capability (per cent macroptery) in populations of the delphacid planthopper Toya venilia were examined throughout the British Virgin Islands. The host plant of this delphacid is salt grass Sporobolus virginicus, which grows either in undisturbed habitats (large expanses on intertidal salt flats and around the margins of salt ponds, or small patches of sparse vegetation on sand dunes along the shore), or in less persistent, disturbed habitats (managed lawns). 2. Both sexes of T. venilia were significantly more macropterous in disturbed habitats (77.1% in males, 12.5% in females) than in more persistent, undisturbed habitats (19.2% in males, < 1% in females). 3. Males exhibited significantly higher levels of macroptery (26.9 ± 7.6%) than did females (2.0 ± 1.7%), and per cent macroptery was positively density dependent for both sexes in field populations. 4. There was no evidence that the low incidence of female macroptery in a subset of island populations inhabiting natural habitats (1.7 ± 1.2%) was attributable to the effects of isolation on oceanic islands. The incidence of macroptery in British Virgin Island populations of T. venilia was not different from that observed in mainland delphacid species existing in habitats of similar duration. 5. Rather, the persistence of most salt grass habitats throughout the British Virgin Islands best explains the evolution of flight reduction in females of this island‐inhabiting delphacid. 6. Males were significantly more macropterous in populations occupying dune vegetation (37.6 ± 9.8%) than in populations occupying salt flat–pond margin habitats (7.6 ± 5.6%). By contrast, females exhibited low levels of macroptery in both dune (0%) and salt flat–pond margin (< 1%) habitats. Variation in salt‐grass structure probably underlies this habitat‐related difference in macroptery because flight‐capable males of planthoppers are better able to locate females in the sparse‐structured grass growing on dunes. This habitat‐related difference in male macroptery accounted for the generally higher level of macroptery observed in males than in females throughout the islands. 7. The importance of habitat persistence and structure in explaining the incidence of dispersal capability in T. venilia is probably indicative of the key role these two factors play in shaping the dispersal strategies of many insects.  相似文献   

10.
We investigated the effects of substrate composition on foraging behavior and growth rate of␣larval green sturgeon, Acipenser medirostris, in the␣laboratory at 20±1°C over a period of 5 weeks. Larval groups (n = 100) with mean wet weight (0.72 ± 0.01 g) at 50 days post-hatch were reared on slate-rocks, cobble, sand or glass. Typically, fish were negatively rheotactic and exhibited dispersed skimming behaviors on provided substrates during pre-feeding and feeding, respectively, but were all positively rheotactic during feeding. Fish reared on slate-rock substrates were negatively phototactic, remained benthic, and aggregated underneath the substrates. In all substrates except slate-rocks, fish displayed frequent episodes of burst and glide swimming activity, tank wall skimming and vertical swimming behaviors, however these behaviors ceased immediately during feeding and reappeared at the end of the feeding period. Substrate composition led to variable foraging effectiveness and likely contributed to significant differences in specific growth rates (2.28, 1.14, 1.77, and 2.27% body weight per day) and mortality (7%, 40%, 11%, 0%) among the treatment groups; slate-rocks, cobble, sand, and glass, respectively. There were no significant differences in morphometrics, somatotopic indices, and whole-body lipid content among treatment groups at the end of the experiment. The present findings indicate that certain substrates in artificial/natural habitats may negatively affect larval growth and may lead to decreased recruitment of juvenile green sturgeon in the wild.  相似文献   

11.
Question: Are the seed banks of an isolated subtropical oceanic island capable of naturally regenerating vegetation either with species of the historical forest community or with the existing grassland community after severe damage to the vegetation by goats? Location: Nakoudojima Island, Bonin Archipelago (Ogasawara Shoto), Japan. Methods: Soil samples were collected at 0–5 cm and 5–10 cm depths from seven plots in forests, grasslands, artificially matted areas and bare land. Soil seed banks were assessed using the seedling emergence method followed by the hand‐sorting of ungerminated seeds. We determined the size and composition of the seed banks in upper soil layers of plots and compared the seed banks to the standing vegetation. Results: A total of 12 220 seedlings belonging to 42 species from 20 families germinated. Total mean seed density (0–5 cm depth) was low in all plots within forest, grassland, and heavily degraded vegetation types (34.7 ± 8.6 to 693.5 ± 123.6, 58.6 ± 7.8 to 107.1 ± 10.0, and 1.1 ± 0.5 to 7.2 ± 2.3 seeds/m2, respectively). Forbs and graminoids dominated the seed banks of grassland and forest plots including Cyperus brevifolius, Gnaphalium pensylvanicum, Oxalis corniculata and Solanum nigrum, and these alien species comprised 90% of the density of the seed bank. There was little correlation between seed banks and standing vegetation of the island (Sørensen similarity coefficient values 0.26 to 0.45). Conclusions: If natural regeneration occurs from the seed bank of the island, future vegetation will not move toward the original forest community, because the seed bank is dominated by non‐native herbaceous grassland species. Though isolated, a few forest remnants with low species richness could be an important source for the natural re‐establishment of forest on the island; however, seed availability may be limited by either poor dispersal or pollination so that woody species will probably recover very slowly on this goat‐impacted island.  相似文献   

12.
This study compared the body composition (fillet yield, chemical composition and lipid quality of fillets) and sensory quality of captured wild (by gillnet in August 2011) with experimentally raised farmed (reared in concrete flow‐through raceways, average water temperature 10 ± 3°C) whitefish, Coregonus macrophthalmus, from Lake Constance. The study was conducted in 2011 using 28 wild and 24 farmed market‐sized fish of approximately equal total lengths (25.1 ± 1.21 and 25.6 ± 1.28 cm). Farmed female Coregonus macrophthalmus exhibited a 3.3% lower fillet yield resulting from larger gonads and a shallower body shape. The protein contents of farmed and wild fillets were equal (17.5% vs. 17.4%), but farmed fish fillets contained less moisture (76.1% vs.77.4%), less ash (1.2% vs. 1.6%), and more lipid (5.1% vs. 4.1%) than wild‐caught specimens. Levels of monounsaturated fatty acids (MUFA) were higher in farmed fish (42.0 vs. 31.0 g/100 g lipid), as well as the levels of polyunsaturated fatty acids (PUFA; 26.0 vs. 19.7 g/100 g lipid), in particular 22:6n?3 (docosahexaenoic acid, DHA; 7.3 vs. 2.1 g/100 g lipid). Conversely, wild fish fillets contained significantly more 20:4n?6 (arachidonic acid, AA; 1.6 vs. 0.4 g/100 g lipid) and 20:5n?3 (eicosapentaenoic acid, EPA; 4.1 vs. 3.2 g/100 g lipid). Sensory evaluation of odour, colour, texture and flavour by an experienced six‐person panel revealed a significant preference for the colour (79% vs. 21%) of farmed fish fillets. In conclusion, farmed whitefish can be strong competitors to wild whitefish in terms of product quality, with higher levels of healthy fatty acids and a more attractive fillet colour. Farmed Coregonus macrophthalmus thus represents a promising and pragmatic approach, compensating for the current capture decline in the whitefish fisheries of Lake Constance.  相似文献   

13.
Objective: A recent study suggested that high concentrations of leptin enhance platelet aggregations. Therefore, the aim of this study was to investigate whether platelet aggregation is altered in patients with leptin gene mutations compared with obese subjects or controls. Research Methods and Procedures: Four men (one homozygous man and his three heterozygous brothers) carrying a leptin gene mutation; 20 age‐matched, healthy, unrelated men; and 18 age‐matched obese men were enrolled in the study. Adenosine diphosphate (ADP)‐, collagen‐, and epinephrine‐induced platelet aggregation were evaluated in all individuals. Results: Our results show that patients with the leptin gene mutation (both the homozygous and heterozygous patients) had significantly higher ADP‐induced (78.3 ± 3.4% vs. 57.9 ± 9.3%, p = 0.001), collagen‐induced (78.1 ± 2.9% vs. 56.7 ± 9.3%, p = 0.007), and epinephrine‐induced (76.5 ± 9.2% vs. 59.5 ± 7.70%, p = 0.003) platelet aggregation compared with controls. However, ADP‐, collagen‐, or epinephrine‐induced platelet aggregations were similar to those in obese patients. Platelet aggregation responses to a combination of pretreatment with leptin at concentrations of 20, 50, 100, or 500 ng/mL for 5 minutes and ADP at concentrations of 2 μmol/liter also were evaluated. However, we did not find significant increases in platelet aggregation even at high concentrations of leptin (100 or 500 ng/mL) in leptin‐deficient patients, obese subjects, or controls. Discussion: Our data show that similar to findings in obese humans, homozygous or heterozygous leptin deficiency is associated with increased platelet aggregation compared with controls, and that higher concentrations of leptin do not increase platelet aggregation.  相似文献   

14.
Aims To quantify pollen–vegetation relationships from saline to freshwater in an estuarine gradient from surface samples of the modern pollen rain, to allow more accurate interpretations of the stratigraphic palynological record. Location Whangapoua Estuary, Great Barrier Island, northern New Zealand. Methods Six transects were laid out along a vegetation sequence running from estuarine mud to freshwater swamp. Along these transect lines, 108 plots were sampled for vegetation and surface sediments from wet sand, mud, plant litter or moss (sand and mud sites are inundated by most tides, other sites less frequently). All sediment samples were analysed for pollen. The relationships between plant species frequency and pollen representation were examined at a community scale using twinspan and ordination analyses, and for individual species using fidelity and dispersibility indices, regression and box‐plot analyses. Results The quantitative relationships between source taxon vegetation frequency and its pollen representation varied between species due to differential pollen production and dispersal. twinspan of the surface pollen samples suggests five vegetation types: (A) mangrove (Avicennia marina); (C) Leptocarpus similis salt meadow; (D) Baumea sedges; (E) Leptospermum shrubland; and (F) Typha/Cordyline swamp forest. The (B) Juncus kraussii community is not represented palynologically owing to the destruction of its delicate pollen grains during acetolysis of samples. Detrended correspondence analysis places these communities on an estuarine‐to‐freshwater gradient. However, pollen assemblages at the seaward end of the salinity gradient are less clearly representative of the associated vegetation than those at the landward end, probably because the open vegetation at the former allows the influx of wind‐ and water‐dispersed pollen from surrounding vegetation. Main conclusions The vegetation pattern (zonation) at Whangapoua is reflected in the pollen rain. When the long‐distance and over‐represented pollen types are excluded, five out of six of the broad vegetation communities can be identified by their pollen spectra. Species with high fidelity and low‐to‐moderate dispersibility indices can be used to identify the vegetation types in the sedimentary sequences. The more open vegetation types at the ‘marine end’ of the sequence tend to be ‘overwhelmed’ by regional pollen, but the nature of the sediments and the presence of discriminatory species (e.g. A. marina, Plagianthus divaricatus, Cordyline australis), even in small amounts, will allow correct identification of the local vegetation represented in sedimentary palynological sequences. A box‐plot analysis indicates that the pollen and spore types A. marina (mangroves), Sarcocornia quinqueflora (salt meadow), P. divaricatus (sedges), Gleichenia (shrubland) and C. australis (swamp forest) are highly discriminatory in relation to vegetation type. These discriminatory palynomorphs help with the interpretation of stratigraphic pollen studies. However, salt marsh vegetation communities in the sediments must be interpreted with caution as the marine sediments are easily affected by erosion, bioturbation and tidal inundation effects.  相似文献   

15.

Potato tuber moth, Phthorimaea ( = Gnorimoschema) operculella (Zeller) (Lepidoptera: Gelechiidae), was reared from egg to adult for 3 generations on an artificial diet. At 30±2°c with a 16‐h photoperiod the total life cycle was completed in 23 days, compared with 18.5 days on potato tubers. Average life cycle data from the 3 generations reared on diet (with corresponding data from tubers in parentheses) are: larval period, 13.0(11.8) days; pupal period, 5–6(4–5) days; survival to adult, 76.1(100)%; fecundity, 102(169) eggs/?; pupal wt‐ ? 8.3(11.4) mg, ? 7.7(9.1) mg.  相似文献   

16.
The effects of temperature (4–20°C), relative humidity (RH, 0–100%), pH (3–7), availability of nutrients (0–5 g/l sucrose) and artificial light (0–494 μmol/m2/s) on macroconidial germination of Fusarium graminearum were studied. Germ tubes emerged between 2 and 6 h after inoculation at 100% RH and 20°C. Incubation in light (205 ± 14 μmol/m/s) retarded the germination for approximately 0.5 h in comparison with incubation in darkness. The times required for 50% of the macroconidia to germinate were 3.5 h at 20°C, 5.4 h at 14°C and 26.3 h at 4°C. No germination was observed after an incubation period of 18 h at 20°C in darkness at RH less than 80%. At RH greater than 80%, germination increased with humidity. Germination was observed when macroconidia were incubated in glucose (5 g/l) or sucrose (concentration range from 2.5 × 10?4 to 5 g/l) whereas no germination was observed when macroconidia were incubated in sterile deionized water up to 22 h. Macroconidia germinated quantitatively within 18 h at pH 3–7. Repeated freezing (?15°C) and thawing (20°C) water agar plates with either germinated or non‐germinated macroconidia for up to five times did not prevent fungal growth after thawing. However, the fungal growth rate of mycelium was negatively related to the number of freezing events the non‐germinated macroconidia experienced. The fungal growth rate of mycelium was not significantly affected by the number of freezing events the germinated spores experienced. Incubation of macroconidia at low humidity (0–53% RH) suppressed germination and decreased the viability of the spores.  相似文献   

17.
α‐Cyclodextrin (α‐CD) is a soluble fiber derived from corn. It has previously been reported that early intervention with Mirafit fbcx, a trademarked name for α‐CD, has beneficial effects on weight management in obese individuals with type 2 diabetes, and that it preferentially reduces blood levels of saturated and trans fats in the LDL receptor knockout mice. The current investigation involves overweight but not obese nondiabetic individuals and was intended to confirm the effects of α‐CD on both weight management and improving blood lipid levels. Forty‐one healthy adults (age: 41.4 ± 13.6 years) participated in this 2‐month, double‐blinded, crossover study. In 28 compliant participants (8 males and 20 females), when the active phase was compared to the control phase, there were significant decreases in body weight (?0.4 ± 0.2 kg, P < 0.05), serum total cholesterol (mean ± s.e.m., ?0.295 ± 0.10 mmol/l, 5.3%, P < 0.02) and low‐density lipoprotein (LDL) cholesterol (?0.23 ± 0.11 mmol/l, ?6.7%, P < 0.05). Apolipoprotein B (Apo B) (?0.0404 ± 0.02 g/l, ?5.6%, P = 0.06) and insulin levels also decreased by 9.5% (?0.16 ± 0.08 pmol/l, P = 0.06) while blood glucose and leptin levels did not change. These results suggest that α‐CD exerts its beneficial health effects on body weight and blood lipid profile in healthy nonobese individuals, as previously reported in obese individuals with type 2 diabetes.  相似文献   

18.
Melittobia acasta (Walker) are microhymenopteran ectoparasitoids of the pupae and prepupae of the commercially‐used pollinator bumblebee species Bombus terrestris L. The female parasitoids puncture the host cuticle with their sting and feed oozing hemolymph. This study shows that M. acasta parasitize 100% pupae and 84% prepupae of B. terrestris but are ineffective on the larvae of the bees. The female parasitoids lay a significantly higher number of eggs on pupae (67.7 ± 16.2 female?1) compared to prepupae (20.5 ± 14.5 female?1). The parasitoids differ in their choice for oviposition sites and fecundity on different locations of B. terrestris pupae, and they show most preference for oviposition (32%) as well as fecundity (34.9 ± 15.1 female?1) on the petiole of the host. Larvae of the parasitoids overwinter at low temperatures but larval overwintering duration and post‐diapause rearing on original or new hosts do not affect their pupation and adult emergence. Larvae have a higher percentage of pupation (88.0–94.4%) and adult emergence (84.4–92.9%) both on the original and the new host, thus indicate that the parasitoids are highly capable of reproduction in B. terrestris colonies.  相似文献   

19.
The study of the biology of the mud shrimp Upogebia issaeffi (Balss, 1913) from the subtidal zone of the Vostok Bay (Peter the Great Bay, Sea of Japan) revealed that this species occurs at depth of 1–6 m on mixed grounds of boulders, gravel, pebbles, shells of dead clams, and silty sand. The average population density of U. issaeffi in the local aggregation on a bottom transect of 300 m length ranged from 0.2 ± 0.4 to 8.0 ± 3.0 ind./m2, the biomass varied from 0.5 ± 1.1 to 78.7 ± 28.3 g/m2, or about 2.7% of the total biomass of macrozoobenthos and 51.2% of the biomass of decapod crustaceans, which is characteristic of the habitats of the mud shrimp. The maximum depth of burrowing of U. issaeffi was 65 cm. The aggregation consisted of animals with body lengths of 44–88 mm. The lifespan of U. issaeffi was 2–3 years. An equilibrium ratio of males and females (1: 1.06) was observed in the population. There were egg clutches on pleopods of 81.7% of the females. The body size of the smallest females with eggs was 67 mm. The larger the females were, the more of them were ovigerous individuals. About 4% of individuals of U. issaeffi were infected with the parasitic isopod Orthione griffenis.  相似文献   

20.
Simple sequence repeats (SSRs) exist in both eukaryotic and prokaryotic genomes and are the most popular genetic markers, but the SSRs of mosquito genomes are still not well understood. In this study, we identified and analyzed the SSRs in 23 mosquito species using Drosophila melanogaster as reference at the whole-genome level. The results show that SSR numbers (33 076-560 175/genome) and genome sizes (574.57-1342.21 Mb) are significantly positively correlated (R~= 0.8992, P < 0.01), but the correlation in individual species varies in these mosquito species. In six types of SSR, mono- to trinucleotide SSRs are dominant with cumulative percentages of 95.14%-99.00% and densities of 195.65/Mb-787.51/Mb, whereas tetra- to hexanucleotide SSRs are rare with 1.12%-4.22% and 3.76/Mb-40.23/Mb. The (A/T)n,(AC/GT)n and (AGC/GCT)n are the most frequent motifs in mononucleotide, dinucleotide and trinucleotide SSRs, respectively, and the motif frequencies of tetra- to hexanucleotide SSRs appear to be species-specific. The 10-20 bp length of SSRs are dominant with the number of 11() 561 ± 93 482 and the frequency of 87.25%± 5.73% on average, and the number and frequency decline with the increase oflength. Most SSRs(83.34%± 7.72%) are located in intergenic regions, followed by intron regions (11.59%± 5.59%), exon regions (3.74%± 1.95%), and untranslated regions (1.32%± 1.39%). The mono-, di- and trinucleotide SSRs are the main SSRs in both gene regions (98.55%± 0.85%) and exon regions (99.27%± 0.52%). An average of 42.52% of total genes contains SSRs, and the preference for SSR occurrenee in different gene subcategories are species-specific. The study provides useful insights into the SSR diversity, characteristics and distribution in 23 mosquito species of genomes.  相似文献   

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