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1.
Wang J  Yang D  Zhang Y  Shen J  van der Gast C  Hahn MW  Wu Q 《PloS one》2011,6(11):e27597
It is widely accepted that biodiversity is lower in more extreme environments. In this study, we sought to determine whether this trend, well documented for macroorganisms, also holds at the microbial level for bacteria. We used denaturing gradient gel electrophoresis (DGGE) with phylum-specific primers to quantify the taxon richness (i.e., the DGGE band numbers) of the bacterioplankton communities of 32 pristine Tibetan lakes that represent a broad salinity range (freshwater to hypersaline). For the lakes investigated, salinity was found to be the environmental variable with the strongest influence on the bacterial community composition. We found that the bacterial taxon richness in freshwater habitats increased with increasing salinity up to a value of 1‰. In saline systems (systems with >1‰ salinity), the expected decrease of taxon richness along a gradient of further increasing salinity was not observed. These patterns were consistently observed for two sets of samples taken in two different years. A comparison of 16S rRNA gene clone libraries revealed that the bacterial community of the lake with the highest salinity was characterized by a higher recent accelerated diversification than the community of a freshwater lake, whereas the phylogenetic diversity in the hypersaline lake was lower than that in the freshwater lake. These results suggest that different evolutionary forces may act on bacterial populations in freshwater and hypersaline lakes on the Tibetan Plateau, potentially resulting in different community structures and diversity patterns.  相似文献   

2.
The aim of this prospective study was to explore predictors of objective career success among Swedish women and men, focussing on gender differences. Data were drawn from the 2008 and 2010 waves of the Swedish Longitudinal Occupational Survey of Health (SLOSH) with a total of 3670 female and 2773 male participants. Odds ratios and 95% confidence intervals for job promotion and an above-average salary increase between 2008 and 2010 were obtained through binary logistic regression analyses. Individual and organisational factors measured in 2008 were used as predictors in analyses stratified by sex. Mutual adjustment was performed for these variables, as well as for labour market sector and staff category at baseline. In both sexes, younger age predicted both job promotion and an above-average salary increase. Job promotion was also in both sexes predicted by being part of decision-making processes, having conflicts with superiors, and being eager to advance. Furthermore, promotion was predicted by, among men, being educated to post-graduate level and having an open coping strategy and, among women, working >60 hours/week. An above-average salary increase was predicted in both sexes by having a university education. Postgraduate education, having children living at home, and being very motivated to advance predicted an above-average salary increase among women, as did working 51–60 hours/week and being part of decision-making processes in men. Gender differences were seen in several predictors. In conclusion, the results support previous findings of gender differences in predictors of career success. A high level of education, motivation to advance, and procedural justice appear to be more important predictors of career success among women, while open coping was a more important predictor among men.  相似文献   

3.
In the Fathala Forest, Saloum Delta National Park, Senegal, in 1974–1976 and 1988–2002, we studied the northernmost populations of the endangered Temminck’s red colobus (Procolobus badius temmincki). Drastic habitat changes in the last 30 yr have reduced the forests by > 50% (75% in the gallery forests used by the red colobus). The woody species diversity decreased by > 30%. Despite these changes, the red colobus population only decreased from ca. 600 to ca. 500 individuals. We examined the ecological conditions and behavioral adaptations that may have influenced survival of the population. We found that 5 major adaptations have emerged in the last 30 yr that may have influenced the survival of red colobus at Fathala: (1) frugivory, (2) terrestriality, (3) tendency to form polyspecific associations with green monkeys, (4) tendency to frequent more open habitats, and (5) use of mangrove swamps for refuge and forage. By developing these adaptations, red colobus demonstrated their ability to persist in degraded habitats of the Fathala Forest. Preserving the forest should ensure the conservation of the red colobus population there.  相似文献   

4.
The symbiotic association between corals and zooxanthellae has been a major contributing factor in the success of reef-building corals. Most of these endocellular microalgal symbionts belong to the dinoflagellate genus Symbiodinium. However, considerable genetic diversity was revealed within this taxon, as is evident in the several clades of Symbiodinium found in association with hermatypic corals all over the world. The coral reefs of Eilat (Aqaba), where winter temperature minima of 21 °C are close to threshold values that prevent reef development, are among the northernmost reefs in the world. Furthermore, due to the circulation patterns of the Gulf, the extremely high evaporation, and lack of any riverine inputs, the Gulf's waters are highly saline (40.5‰). In spite of the extreme location, a high diversity of coral species has been reported in this area. In this study, using PCR, we specifically amplified zooxanthellae 18S ribosomal DNA from symbionts of 11 coral species, and analyzed it with respect to RFLP and DNA sequence.Of the several clades described from the same coral hosts in other localities, only A and C were found in the present study. Symbiodinium populations in the host examined from Eilat were different relative to other parts of the world. This distribution is discussed in relation to reproduction strategy: broadcasting versus brooding. Based on our results, we suggest that clade A is transferred through a closed system. As mass bleaching in the Gulf has never been observed, we suggest that the adaptive mechanisms presumably favoring clade diversity were not yet significant in our relatively cool area.  相似文献   

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6.
International Journal of Primatology - Overhunting and habitat loss from the expansion of agriculture and extractive industries are the primary threats to primate species, 65% of which are...  相似文献   

7.
The chromalveolate "supergroup" is of key interest in contemporary phycology, as it contains the overwhelming majority of extant algal species, including several phyla of key importance to oceanic net primary productivity such as diatoms, kelps, and dinoflagellates. There is also intense current interest in the exploitation of these algae for industrial purposes, such as biodiesel production. However, the evolution of the constituent species, and in particular the origin and radiation of the chloroplast genomes, remains poorly understood. In this review, we discuss current theories of the origins of the extant red alga-derived chloroplast lineages in the chromalveolates and the potential ramifications of the recent discovery of large numbers of green algal genes in chromalveolate genomes. We consider that the best explanation for this is that chromalveolates historically possessed a cryptic green algal endosymbiont that was subsequently replaced by a red algal chloroplast. We consider how changing selective pressures acting on ancient chromalveolate lineages may have selectively favored the serial endosymbioses of green and red algae and whether a complex endosymbiotic history facilitated the rise of chromalveolates to their current position of ecological prominence.  相似文献   

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Simian retroviruses are precursors of all human retroviral pathogens. However, little is known about the prevalence and coinfection rates or the genetic diversity of major retroviruses—simian immunodeficiency virus (SIV), simian T-cell lymphotropic virus type 1 (STLV-1), and simian foamy virus (SFV)—in wild populations of nonhuman primates. Such information would contribute to the understanding of the natural history of retroviruses in various host species. Here, we estimate these parameters for wild West African red colobus monkeys (Piliocolobus badius badius) in the Taï National Park, Côte d''Ivoire. We collected samples from a total of 54 red colobus monkeys; samples consisted of blood and/or internal organs from 22 monkeys and additionally muscle and other tissue samples from another 32 monkeys. PCR analyses revealed a high prevalence of SIV, STLV-1, and SFV in this population, with rates of 82%, 50%, and 86%, respectively. Forty-five percent of the monkeys were coinfected with all three viruses while another 32% were coinfected with SIV in combination with either STLV or SFV. As expected, phylogenetic analyses showed a host-specific pattern for SIV and SFV strains. In contrast, STLV-1 strains appeared to be distributed in genetically distinct and distant clades, which are unique to the Taï forest and include strains previously described from wild chimpanzees in the same area. The high prevalence of all three retroviral infections in P. b. badius represents a source of infection to chimpanzees and possibly to humans, who hunt them.Lentiviruses and deltaretroviruses that infect African nonhuman primates have received considerable attention as they are the precursors of all pathogenic human retroviruses: human immunodeficiency virus types 1 and 2 (HIV-1/HIV-2) and human T-cell lymphotropic virus type 1 (HTLV-1). These human infections are the results of past zoonotic transfers of simian immunodeficiency virus (SIV) and simian T-cell lymphotropic viruses type 1 (STLV-1) from wild monkeys and apes into local human populations, presumably through primate hunting and handling of primate bushmeat (13, 19, 43, 46, 55, 58, 59). Via the same route, zoonotic transmission of simian foamy virus (SFV), a spumaretrovirus whose exact pathogenicity in human hosts is still unknown, has also been shown (64). The increasing contact between humans and wild primates implies that further zoonotic transmission of retroviruses is likely to happen (42, 63). Studying the occurrence and circulation of simian retroviruses such as SIV, STLV-1, and SFV in wild primate populations enables us to better understand retrovirus evolution in primates and also provides tools for monitoring possible future retroviral zoonotic events.Systematic studies of SIV, STLV-1, and SFV in wild primates are relatively rare. Many use bushmeat samples, which can vary in their quality and are prone to cross-contamination from butchering and storage with other carcasses. Confiscated primates are also not representative of the situation in the wild since the animals are caught at a young age when the occurrence of different retroviruses may be extremely low (24). The technical possibilities for the detection of various pathogens in noninvasive samples such as urine and feces have greatly improved and are frequently used; however, in general, the sensitivity of detection methods is higher when blood and tissue samples are used (25, 32, 47). Such samples can be collected if fresh carcasses are found, or they can be collected by anesthetizing live primates for sampling purpose, animal translocation, or medical intervention, such as snare removal. The practical and ethical issues of each of the sampling methods have been discussed elsewhere (12, 14).Red colobus monkeys [Procolobus (Piliocolobus)] are interesting subjects for retroviral infection studies for a number of reasons. First, they are widely distributed (yet in a fragmented manner) from East to West Africa, which suggests that red colobus species and subspecies, or more likely ancestor(s) of these, could have been key hosts in transmitting retroviruses across tropical Africa (4, 54). Second, as they are herbivore primates, the hunting of other primates can be excluded as a route of infection. Finally, these monkeys are frequently hunted by humans and chimpanzees and represent a possibly large reservoir for retroviruses and other pathogens that ought to be investigated further (2, 45).Very little information is available about the prevalence and coinfection of SIV, STLV-1, and SFV in wild red colobus monkeys across Africa. In other colobine monkeys only SIV has been documented: in olive colobus (Procolobus verus) in Côte d''Ivoire and in black and white colobus (Colobus guereza) in Cameroon (7, 8). Based on fecal samples from habituated adult individuals, the prevalence of SIV in West African red colobus monkeys (SIVwrc; local subspecies, Piliocolobus badius badius) has been estimated to a minimum of 26% in the Taï National Park, Côte d''Ivoire, but the authors recognized the low sensitivity of viral RNA detection in fecal samples (34). Another study conducted on the same population revealed that 5 out of 10 blood samples were SIV positive (7). These results highlight that the most reliable prevalence data are based on analyses of blood/tissue samples although such sampling is not always feasible for reasons discussed above. Published prevalence information concerning STLV-1 and SFV in wild red colobus monkeys (STLV-1wrc and SFVwrc) in the same area is restricted to results obtained from analyses of a limited number of blood and necropsy samples collected as a part of studies whose focus was on cross-species transmission of these two viruses to chimpanzees (27, 28). However, these samples indicated a high prevalence of STLV-1wrc and SFVwrc in the red colobus monkey population (56% and 90%, respectively). A recent study from Uganda, East Africa, estimated the prevalence of SIV, STLV-1, and SFV in another red colobus species (Piliocolobus rufomitratus tephrosceles) to be 22.6%, 6.4%, and 97%, respectively (15). The study was performed using blood samples collected from anesthetized wild red colobus monkeys living in their natural habitat, which allowed reliable assessment of the prevalence and genetic diversity of these three retroviruses.The preliminary data from the Taï National Park indicate that there might be great variation in the prevalence of retroviruses across the African continent, even in closely related species of wild primates. Here, we aimed at generating reliable prevalence and coinfection data for SIVwrc, STLV-1wrc, and SFVwrc based on the analysis of blood and tissue samples from wild Western red colobus monkeys. We expected that this would allow for proper comparison of retroviral prevalence in the allied species P. b. badius and P. r. tephrosceles.  相似文献   

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After emergence from pupae males and females of Adalia bipunctata reared under the same constant conditions showed similar refractory periods in their mating behavior. The statistically significant slight protogyny might indicate that it is advantageous for females to accept mating and store sperm for a short period prior to becoming sexually mature, whereas males need to become sexually mature in order to mate. As the two-spot ladybird has overlapping generations, theory predicts that the most effective strategy for both sexes is to have similar sexual maturation periods. The results of this study support this prediction. The actual lengths of the maturation periods, however, will depend largely on the prevailing temperatures and the quality and quantity of food available to the beetle.  相似文献   

13.
Disparity, or morphological diversity, is often quantified by evolutionary biologists investigating the macroevolutionary history of clades over geological timescales. Disparity is typically quantified using proxies for morphology, such as measurements, discrete anatomical characters, or geometric morphometrics. If different proxies produce differing results, then the accurate quantification of disparity in deep time may be problematic. However, despite this, few studies have attempted to examine disparity of a single clade using multiple morphological proxies. Here, as a case study for this question, we examine the disparity of the volant Mesozoic fossil reptile clade Pterosauria, an intensively studied group that achieved substantial morphological, ecological and taxonomic diversity during their 145+ million-year evolutionary history. We characterize broadscale patterns of cranial morphological disparity for pterosaurs for the first time using landmark-based geometric morphometrics and make comparisons to calculations of pterosaur disparity based on alternative metrics. Landmark-based disparity calculations suggest that monofenestratan pterosaurs were more diverse cranially than basal non-monofenestratan pterosaurs (at least when the aberrant anurognathids are excluded), and that peak cranial disparity may have occurred in the Early Cretaceous, relatively late in pterosaur evolution. Significantly, our cranial disparity results are broadly congruent with those based on whole skeleton discrete character and limb proportion data sets, indicating that these divergent approaches document a consistent pattern of pterosaur morphological evolution. Therefore, pterosaurs provide an exemplar case demonstrating that different proxies for morphological form can converge on the same disparity signal, which is encouraging because often only one such proxy is available for extinct clades represented by fossils. Furthermore, mapping phylogeny into cranial morphospace demonstrates that pterosaur cranial morphology is significantly correlated with, and potentially constrained by, phylogenetic relationships.  相似文献   

14.
Santamaría  L.  Dias  C.  Hootsmans  M. J. M. 《Hydrobiologia》1994,(1):219-231
In a laboratory experiment, Ruppia drepanensis Tineo seedlings from a brackish marsh in Southern Spain were grown at 20 and 30 °C, at three different nitrogen levels. These levels were obtained by the addition of a slow release fertilizer (23% NH4NO3 by weight) to a sediment mixture of sand and clay (3:1). Several morphometric parameters were recorded during the first five weeks of the experiment, and photosynthesis and respiration were measured after 7 weeks of growth. Results showed a significant reduction of growth and development with increasing nitrogen and temperature levels. Dark respiration increased strongly at high nitrogen levels. At the same time, net photosynthesis at 250 and 500 µE m-2 s-1, Pm, Km and LCP were not affected by either factor. We attribute these phenomena to ammonia toxicity, since relatively high total ammonia (NH3 + NHf4 p+) levels were found in the interstitial water.  相似文献   

15.
Prophylactic administration of the dipeptide homocarnosine induced a high degree of resistance to staphylococcal infections in Swiss albino mice. It expressed its antistaphylococcal properties 1 hr after administration, and this protection lasted for at least 1 month. Although 5 mg per animal (approximately 200 to 250 mg/kg) was routinely used in our studies, experiments showed that comparable results could be obtained with 1.5 mg per animal. Rechallenge experiments indicated that an active infection by itself may confer immunity up to 4 weeks, but an infection after treatment with homocarnosine gave complete immunity to reinfection for at least 2 months. Studies in vitro showed that homocarnosine had no effect on the growth or certain other characteristics (ability to ferment mannitol, liquefy gelatin, and to produce coagulase, deoxyribonuclease, and pigment) of S. aureus. It appears that resistance induced by this peptide is an indirect effect mediated by some nonimmunological host reaction. The possible involvement of homocarnosine, among other compounds, in the protective action of deproteinized beef extract against staphylococcal infections is suggested.  相似文献   

16.
Dormant buds collected from 35 wild service trees (Sorbus torminalis) in the Bytyń Forest were tested with horizontal gel electrophoresis to assess the genetic structure of the population. Among 16 investigated isozyme loci, seven loci (ADH-A, 6PGD-A, GDH-B, ME-A, SOD-A, PGM-A, PGM-B) proved to be polymorphic, whereas the other nine loci (SDH-A, SDH-B, DIA-C, DIA-D, FLE-A, FLE-B, GOT-B, IDH-A, IDH-B) were monomorphic. The number of alleles per polymorphic locus ranged from two to three, with a mean of 2.29. The average observed and expected heterozygosities were 0.2665 and 0.3462, respectively. The combined FIS value over all polymorphic loci was 0.2179, which reflects a substantial deficit of heterozygotes. Two polymorphic loci (SOD-A, PGM-A) were identified in S. torminalis for the first time.  相似文献   

17.
Why Is Golden Rice Golden (Yellow) Instead of Red?   总被引:6,自引:0,他引:6       下载免费PDF全文
The endosperm of Golden Rice (Oryza sativa) is yellow due to the accumulation of beta-carotene (provitamin A) and xanthophylls. The product of the two carotenoid biosynthesis transgenes used in Golden Rice, phytoene synthase (PSY) and the bacterial carotene desaturase (CRTI), is lycopene, which has a red color. The absence of lycopene in Golden Rice shows that the pathway proceeds beyond the transgenic end point and thus that the endogenous pathway must also be acting. By using TaqMan real-time PCR, we show in wild-type rice endosperm the mRNA expression of the relevant carotenoid biosynthetic enzymes encoding phytoene desaturase, zeta-carotene desaturase, carotene cis-trans-isomerase, beta-lycopene cyclase, and beta-carotene hydroxylase; only PSY mRNA was virtually absent. We show that the transgenic phenotype is not due to up-regulation of expression of the endogenous rice pathway in response to the transgenes, as was suggested to be the case in tomato (Lycopersicon esculentum) fruit, where CRTI expression resulted in a similar carotenoid phenomenon. This means that beta-carotene and xanthophyll formation in Golden Rice relies on the activity of constitutively expressed intrinsic rice genes (carotene cis-trans-isomerase, alpha/beta-lycopene cyclase, beta-carotene hydroxylase). PSY needs to be supplemented and the need for the CrtI transgene in Golden Rice is presumably due to insufficient activity of the phytoene desaturase and/or zeta-carotene desaturase enzyme in endosperm. The effect of CRTI expression was also investigated in leaves of transgenic rice and Arabidopsis (Arabidopsis thaliana). Here, again, the mRNA levels of intrinsic carotenogenic enzymes remained unaffected; nevertheless, the carotenoid pattern changed, showing a decrease in lutein, while the beta-carotene-derived xanthophylls increased. This shift correlated with CRTI-expression and is most likely governed at the enzyme level by lycopene-cis-trans-isomerism. Possible implications are discussed.  相似文献   

18.
Two high doses of ivermectin (630 μg/kg and 700 μg/kg) that are sold commercially in Brazil were evaluated in dose-and-slaughter trials with 144 naturally nematode-infected cattle from eight regions within the states of Minas Gerias, São Paulo and Rio Grande do Sul in Brazil. Treatment groups were based on fecal egg counts 1, 2, and 3 days before treatment; all animals studied had a minimum egg count of at least 500 eggs per gram of feces (EPG). Post-mortem analyses were conducted on day 14. The highest levels of resistance to ivermectin were found for Haemonchus placei, Cooperia punctata and Oesophagostomum radiatum; all populations of H. placei were resistant to the 630 μg/kg dose, and 67% were resistant to 700 μg/kg; 86% of C. punctata were resistant to the 630 μg/kg dose, and 33% were resistant to 700 μg/kg. A combined analysis revealed that 57% of O. radiatum were resistant to the lower dose of ivermectin. H. placei, C. punctata and O. radiatum, in order, were the nematode populations with the highest indices of resistance, whereas Trichostrongylus axei was the most susceptible to 630 and 700 μg/kg dosages of ivermectin. The results of helminthic resistance to ivermectin for different populations of H. placei and C. punctata described in the present study support previous literature data, in which a small decrease in the average parasitic burden of C. punctata and a consequent increase of H. placei were observed in cattle from the Southeast, South and Center-West regions of Brazil.  相似文献   

19.
An important programme of biomonitoring along the coast of Algeciras Bay (Straits of Gibraltar) has allowed us tentatively to consider six species of boring sponges of the genus Cliona as biological indicators: Cliona celata, C. viridis, C. rhodensis, C. vermifera, C. schmidti and C. vastifica. The taxonomy and distribution of these species have been considered in this paper. Ecological observations have permitted us to identify some important characteristics of their habitat on the basis of local environmental parameters. Cliona viridis and C. celata withstand sedimentation higher than 7 gr/m2 and a solid suspension of 38 mg/1. Cliona vermifera and C. schmidti did not tolerate sedimentation higher than 1 gr/m2. One of these, C. vermifera Hancock, is recorded for the first time in the Iberian Peninsula.  相似文献   

20.

Background

Schistosomiasis and soil-transmitted helminthiasis are important public health problems in sub-Saharan Africa causing malnutrition, anemia, and retardation of physical and cognitive development. However, the effect of these diseases on physical fitness remains to be determined.

Methodology

We investigated the relationship between schistosomiasis, soil-transmitted helminthiasis and physical performance of children, controlling for potential confounding of Plasmodium spp. infections and environmental parameters (i.e., ambient air temperature and humidity). A cross-sectional survey was carried out among 156 school children aged 7–15 years from Côte d''Ivoire. Each child had two stool and two urine samples examined for helminth eggs by microscopy. Additionally, children underwent a clinical examination, were tested for Plasmodium spp. infection with a rapid diagnostic test, and performed a maximal multistage 20 m shuttle run test to assess their maximal oxygen uptake (VO2 max) as a proxy for physical fitness.

Principal Findings

The prevalence of Schistosoma haematobium, Plasmodium spp., Schistosoma mansoni, hookworm and Ascaris lumbricoides infections was 85.3%, 71.2%, 53.8%, 13.5% and 1.3%, respectively. Children with single, dual, triple, quadruple and quintuple species infections showed VO2 max of 52.7, 53.1, 52.2, 52.6 and 55.6 ml kg−1 min−1, respectively. The VO2 max of children with no parasite infections was 53.5 ml kg−1 min−1. No statistically significant difference was detected between any groups. Multivariable analysis revealed that VO2 max was influenced by sex (reference: female, coef. = 4.02, p<0.001) and age (years, coef. = −1.23, p<0.001), but not by helminth infection and intensity, Plasmodium spp. infection, and environmental parameters.

Conclusion/Significance

School-aged children in Côte d''Ivoire showed good physical fitness, irrespective of their helminth infection status. Future studies on children''s physical fitness in settings where helminthiasis and malaria co-exist should include pre- and post-intervention evaluations and the measurement of hemoglobin and hematocrit levels and nutritional parameters as potential co-factors to determine whether interventions further improve upon fitness.  相似文献   

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