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1.
Since its introduction into eastern North America in the 1940s, the eastern population of house finches (Carpodacus mexicanus) has become partially migratory, unlike its nonmigratory source population in southern California (Able and Belthoff in Proc. R. Soc. Lond. 265 (1410), 2063–2071, 1998; Belthoff and Gauthreaux in Condor 93, 374–382, 1991). The infectious disease mycoplasmal conjunctivitis (pathogen Mycoplasma gallisepticum or “MG”), which has been monitored in the house finch population since its appearance around 1993 (Dhondt et al. in J. Wild. Dis. 34 (2), 265–280, 1998), may induce higher mortality rates among populations in more northerly latitudes relative to more southerly populations. Here, we investigate the potential impact of this differential disease mortality on the migratory structure of the eastern house finch population using an epidemic modeling approach. Analytical and computational results suggest the ongoing MG epidemic in the eastern house finch could lead to increases in the percentage of and the total number of migrating individuals in a population despite overall population declines, assuming relatively high winter mortality rates in the north eastern part of their range. These results also suggest that empirical evidence of such a change in migratory structure would be most noticeable in northerly inland populations that showed significant declines following the initial outbreak of MG in the east.  相似文献   

2.
To select appropriate recovery strategies for endangered populations, we must understand the dynamics of small populations and distinguish between the possible causes that drive such populations to low numbers. It has been suggested that the pattern of population decline may be inversely density-dependent with population growth rates decreasing as populations become very small; however, empirical evidence of such accelerated declines at low densities is rare. Here we analyzed the pattern of decline of a threatened population of woodland caribou (Rangifer tarandus caribou) in British Columbia, Canada. Using information on the instantaneous rate of increase relative to caribou density in suitable winter foraging habitat, as well as on pregnancy rates and on causes and temporal distribution of mortalities from a sample of 349 radiocollared animals from 15 subpopulations, we tested 3 hypothesized causes of decline: (a) food regulation caused by loss of suitable winter foraging habitat, (b) predation-sensitive foraging caused by loss of suitable winter foraging habitat and (c) predation with caribou being secondary prey. Population sizes of caribou subpopulations ranged from <5 to >500 individuals. Our results showed that the rates of increase of these subpopulations varied from −0.1871 to 0.0496 with smaller subpopulations declining faster than larger subpopulations. Rates of increase were positively related to the density of caribou in suitable winter foraging habitat. Pregnancy rates averaged 92.4% ±2.24 and did not differ among subpopulations. In addition, we found predation to be the primary cause of mortality in 11 of 13 subpopulations with known causes of mortality and predation predominantly occurred during summer. These results are consistent with predictions that caribou subpopulations are declining as a consequence of increased predation. Recovery of these woodland caribou will thus require a multispecies perspective and an appreciation for the influence of inverse density dependence on population trajectories.  相似文献   

3.
In this study we used tightly-coupled mitochondria from Yarrowia lipolytica and Dipodascus (Endomyces) magnusii yeasts, possessing a respiratory chain with the usual three points of energy conservation. High-amplitude swelling and collapse of the membrane potential were used as parameters for demonstrating induction of the mitochondrial permeability transition due to opening of a pore (mPTP). Mitochondria from Y. lipolytica, lacking a natural mitochondrial Ca2+ uptake pathway, and from D. magnusii, harboring a high-capacitive, regulated mitochondrial Ca2+ transport system (Bazhenova et al. J Biol Chem 273:4372–4377, 1998a; Bazhenova et al. Biochim Biophys Acta 1371:96–100, 1998b; Deryabina and Zvyagilskaya Biochemistry (Moscow) 65:1352–1356, 2000; Deryabina et al. J Biol Chem 276:47801–47806, 2001) were very resistant to Ca2+ overload. However, exposure of yeast mitochondria to 50–100 μM Ca2+ in the presence of the Ca2+ ionophore ETH129 induced collapse of the membrane potential, possibly due to activation of the fatty acid-dependent Ca2+/nH+-antiporter, with no classical mPTP induction. The absence of response in yeast mitochondria was not simply due to structural limitations, since large-amplitude swelling occurred in the presence of alamethicin, a hydrophobic, helical peptide, forming voltage-sensitive ion channels in lipid membranes. Ca2+- ETH129-induced activation of the Ca2+/H+-antiport system was inhibited and prevented by bovine serum albumin, and partially by inorganic phosphate and ATP. We subjected yeast mitochondria to other conditions known to induce the permeability transition in animal mitochondria, i.e., Ca2+ overload (in the presence of ETH129) combined with palmitic acid (Mironova et al. J Bioenerg Biomembr 33:319–331, 2001; Sultan and Sokolove Arch Biochem Biophys 386:37–51, 2001), SH-reagents, carboxyatractyloside (an inhibitor of the ADP/ATP translocator), depletion of intramitochondrial adenine nucleotide pools, deenergization of mitochondria, and shifting to acidic pH values in the presence of high phosphate concentrations. None of the above-mentioned substances or conditions induced a mPTP-like pore. It is thus evident that the permeability transition in yeast mitochondria is not coupled with Ca2+ uptake and is differently regulated compared to the mPTP of animal mitochondria.  相似文献   

4.
Siderophore production by marine-derived fungi   总被引:1,自引:0,他引:1  
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5.
Amphetamine (AMPH) and its derivatives are regularly used in the treatment of a wide array of disorders such as attention-deficit hyperactivity disorder (ADHD), obesity, traumatic brain injury, and narcolepsy (Prog Neurobiol 75:406–433, 2005; J Am Med Assoc 105:2051–2054, 1935; J Am Acad Child Adolesc Psychiatry 41:514–521, 2002; Neuron 43:261–269, 2004; Annu Rev Pharmacol Toxicol 47:681–698, 2007; Drugs Aging 21:67–79, 2004). Despite the important medicinal role for AMPH, it is more widely known for its psychostimulant and addictive properties as a drug of abuse. The primary molecular targets of AMPH are both the vesicular monoamine transporters (VMATs) and plasma membrane monoamine—dopamine (DA), norepinephrine (NE), and serotonin (5-HT)—transporters. The rewarding and addicting properties of AMPH rely on its ability to act as a substrate for these transporters and ultimately increase extracellular levels of monoamines. AMPH achieves this elevation in extracellular levels of neurotransmitter by inducing synaptic vesicle depletion, which increases intracellular monoamine levels, and also by promoting reverse transport (efflux) through plasma membrane monoamine transporters (J Biol Chem 237:2311–2317, 1962; Med Exp Int J Exp Med 6:47–53, 1962; Neuron 19:1271–1283, 1997; J Physiol 144:314–336, 1958; J Neurosci 18:1979–1986, 1998; Science 237:1219–1223, 1987; J Neurosc 15:4102–4108, 1995). This review will focus on two important aspects of AMPH-induced regulation of the plasma membrane monoamine transporters—transporter mediated monoamine efflux and transporter trafficking.  相似文献   

6.
Many association methods use a subset of genotyped single nucleotide polymorphisms (SNPs) to capture or infer genotypes at other untyped SNPs. We and others previously showed that tag SNPs selected to capture common variation using data from The International HapMap Consortium (Nature 437:1299–1320, 2005), The International HapMap Consortium (Nature 449:851–861, 2007) could also capture variation in populations of similar ancestry to HapMap reference populations (de Bakker et al. in Nat Genet 38:1298–1303, 2006; González-Neira et al. in Genome Res 16:323–330, 2006; Montpetit et al. in PLoS Genet 2:282–290, 2006; Mueller et al. in Am J Hum Genet 76:387–398, 2005). To capture variation in admixed populations or populations less similar to HapMap panels, a “cosmopolitan approach,” in which all samples from HapMap are used as a single reference panel, was proposed. Here we refine this suggestion and show that use of a “weighted reference panel,” constructed based on empirical estimates of ancestry in the target population (relative to available reference panels), is more efficient than the cosmopolitan approach. Weighted reference panels capture, on average, only slightly fewer common variants (minor allele frequency > 5%) than the cosmopolitan approach (mean r 2 = 0.977 vs. 0.989, 94.5% variation captured vs. 96.8% at r 2 > 0.8), across the five populations of the Multiethnic Cohort, but entail approximately 25% fewer tag SNPs per panel (average 538 vs. 718). These results extend a recent study in two Indian populations (Pemberton et al. in Ann Hum Genet 72:535–546, 2008). Weighted reference panels are potentially useful for both the selection of tag SNPs in diverse populations and perhaps in the design of reference panels for imputation of untyped genotypes in genome-wide association studies in admixed populations. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.  相似文献   

7.
A major scab resistance gene initially called Vr1 was identified in the apple cultivar “Regia” derived from the Malus scab resistance source R12740-7A (Russian seedling, RS). A codominant, multiallelic sequence characterized amplified region (SCAR) marker was developed from a random amplified polymorphic DNA marker identified by bulked-segregant analysis. Additional alleles of the AD13 marker locus proved to be informative for the analysis of genetic relationships within Malus including putative relatives of RS. Separate linkage maps were created for the two families derived from crosses with “Regia”. Using phenotypic data from the greenhouse scab tests, the recombination frequency between Vr1 and AD13-SCAR was between 6 and 17%. The Vr1 locus appeared to be closely linked to the Vx [Hemmat et al. J Am Soc Hortic Sci, 127:365–370, 2002], Vr2 [Patocchi et al. Theor Appl Genet, 109:1087–1092, 2004], and the Vh4 gene [Bus et al. Mol Breed, 15:103–116, 2005a]. Our linkage analysis of the molecular markers identified by Hemmat et al. [J Am Soc Hortic Sci, 127:365–370, 2002] for two scab resistance factors from RS (Vr and Vx) indicate that both genes are separated by a large distance on apple linkage group 2 [Boudichevskaia et al. Acta Hortic, 663:171–175, 2004]. This is in agreement with the results of Bus et al., [Mol Breed, 15:103–116, 2005a] who concluded that (1) the RS-derived gene Vh2 is identical to Vr, (2) the RS-derived gene Vh4 is identical to Vx and Vr1, (3) Vh2/Vr and Vh4/Vr1/Vx map on opposite sides of LG 2. One of our main goals was the verification of the Vr1-SCAR within a practical apple-breeding program. The utility of the AD13-SCAR was evident after 2 years under natural scab infection conditions in both families investigated. This is the first report about the confirmation of a molecular marker for a RS resistance factor in a 2-year field experiment. A multiplex polymerase chain reaction assay based on two codominant SCARs for Vf and Vr1 was tested in an apple progeny segregating for both genes. The result of the two-marker approach is discussed with respect to scab races, which are able to overcome the Vf resistance gene.  相似文献   

8.
Over the past 57 years, 17 recipients of frozen bone have been infected with: HIV (Centers for Disease Control and Prevention in Morb Mortal Wkly Rep MMWR 37(39):597–599, 1988; Li et al. in J Formos Med Assoc 100(5):350–351, 2001; Simonds et al. in NEJM 326(11):726–732, 1992; Schratt et al. in Unfallchirurg 99(9):679–684, 1996); HCV (Eggen and Nordbo in NEJM 326(6):411, 1992; Conrad et al. in J Bone Joint Surg Am 77:214–224, 1995; Trotter in J Bone Joint Surg Am 851(11):2215–2217, 2003; Tugwell et al. in Ann of Internal Med 143(9):648–654, 2005); or HBV (Shutkin in J Bone Joint Surg Am 36:160–162, 1954). However, bone, lyophilized and stored at room temperature, has never transmitted these viral diseases. A literature review was undertaken to determine whether there is any evidence that lyophilized bone is capable of transmitting HIV, HCV and HBV.  相似文献   

9.
Population increases of primary prey can negatively impact alternate prey populations via demographic and behavioural responses of a shared predator through apparent competition. Seasonal variation in prey selection patterns by predators also can affect secondary and incidental prey by reducing spatial separation. Global warming and landscape changes in Alberta's bitumen sands have resulted in prey enrichment, which is changing the large mammal predator–prey system and causing declines in woodland caribou Rangifer tarandus caribou populations. We assessed seasonal patterns of prey use and spatial selection by wolves Canis lupus in two woodland caribou ranges in northeastern Alberta, Canada, that have undergone prey enrichment following recent white‐tailed deer Odocoileus virginianus invasion. We determined whether risk of predation for caribou (incidental prey) and the proportion of wolf‐caused‐caribou mortalities varied with season. We found that wolves showed seasonal variation in primary prey use, with deer and beaver Castor canadensis being the most common prey items in wolf diet in winter and summer, respectively. These seasonal dietary patterns were reflected in seasonal wolf spatial resource selection and resulted in contrasting spatial relationships between wolves and caribou. During winter, wolf selection for areas used by deer maintained strong spatial separation between wolves and caribou, whereas wolf selection for areas used by beaver in summer increased the overlap with caribou. Changing patterns in wolf resource selection were reflected by caribou mortality patterns, with 76.2% of 42 adult female caribou mortalities occurring in summer. Understanding seasonal patterns of predation following prey enrichment in a multiprey system is essential when assessing the effect of predation on an incidental prey species. Our results support the conclusion that wolves are proximately responsible for woodland caribou population declines throughout much of their range.  相似文献   

10.
In the Baltic Sea, herring (Clupea harengus membras) spawns in the littoral zone, where its eggs are attached to algae or vascular plants. Field studies indicate that egg mortality can be very high (up to 100%) in eggs that are attached to red algae (Rajasilta et al., 1989, 1993). Because high mortality can be due to allelochemical effects of the algae, we studied the mortality of herring eggs on different algal substrates experimentally. Four types of substrates were tested: fresh Cladophora and Furcellaria, and Furcellaria that had decomposed six days or 23 days. The incubation time in the experiments was 3 days and incubation temperature 12–13 oC (ca. 700–800 h-degrees). The results were in accordance with observations made in field studies and indicated significant differences among the substrate types. In eggs attached to fresh Cladophora, mortality was significantly lower (mean=2.8%; n=20) than in those attached to Furcellaria, independently of the treatment of the algae. The highest values of mortality (mean=14.4%; n=20) were found in eggs attached to Furcellaria that had decomposed over a six days’ period. This suggested that Furcellaria contain some chemical substances, which can cause mortality in herring embryos and the effect seems to be dependent on the state of decomposition of the algae.  相似文献   

11.
Pheromones cause dramatic changes in behavior and physiology, and are critical for honey bee colony organization. Queen mandibular pheromone (QMP) regulates multiple behaviors in worker bees (Slessor et al. in J Chem Ecol 31(11):2731–2745, 2005). We also identified genes whose brain expression levels were altered by exposure to QMP (Grozinger et al. in Proc Natl Acad Sci USA 100(Suppl 2):14519–14525, 2003). Krüppel-homolog 1 (Kr-h1) RNA levels were significantly downregulated by QMP, and were higher in foragers than in nurses (Whitfield et al. in Science 302(5643):296–299, 2003). Here we report on results of behavioral and pharmacological experiments that characterize factors regulating expression of Kr-h1. Foragers have higher brain levels of Kr-h1 than in-hive bees, regardless of age and pheromone exposure. Furthermore, forager Kr-h1 levels were not affected by QMP. Since the onset of foraging is caused, in part, by increasing juvenile hormone blood titers and brain octopamine levels, we investigated the effects of octopamine and methoprene (a juvenile hormone analog) on Kr-h1 expression. Methoprene produced a marginal (not significant) increase in Kr-h1 expression, but Kr-h1 brain levels in methoprene-treated bees were no longer downregulated by QMP. Octopamine did not modulate Kr-h1 expression. Our results demonstrate that the gene expression response to QMP is not hard-wired in the brain but is instead dependent on worker behavioral state.  相似文献   

12.
Dryopteris is one of the largest and most taxonomically complex fern genera in the Dryopteridaceae, with 127 species occurring throughout temperate, sub-temperate, subtropical, and tropical China. Investigations of the evolutionary relationships of a subset of these Chinese Dryopteris species, using DNA sequence-based methods, specifically tested the monophyly of the genus and the validity of the previous subgeneric classifications. Sixty species of Dryopteris, four closely related non-Dryopteris and three species of Arachniodes, were used as outgroup taxa. The rps4-trnS region of the chloroplast genome was sequenced in these species for the first time. Both maximum parsimony (MP) and neighbor-joining (NJ) analyses identified six polyphyletic clades that contained Dryopteris species. These results were supported by a Bayesian analysis of the same data set. The phylogenetic patterns strongly suggest the polyphyletic status of Dryopteris; the monophyletic groupings of the species do not correspond with either Fraser-Jenkins [In: Bull Brit Mus (Nat Hist) Bot 14(3):183–218, 1986} or Wu (In: Flora Reipublica Popularis Sinicae Tomus 5 (1) pp 1–241, 2000] subgeneric classification of Dryopteris, except in a few specific cases. This work represents the first molecular systematic analyses of Chinese Dryopteris, and we propose the next steps necessary to recognize new subgenera of the genus.  相似文献   

13.
Meta-analysis is being increasingly used as a tool for integrating data from different studies of complex phenotypes, because the power of any one study to identify causal loci is limited. We applied a novel meta-analytical approach (Loesgen et al. in Genet Epidemiol 21(Suppl 1):S142–S147, 2001) in compiling results from four studies of rheumatoid arthritis in Caucasians including two studies from NARAC (Jawaheer et al. in Am J Hum Genet 68:927–936, 2001; Jawaheer et al. in Arthritis Rheum 48:906–916, 2003), one study from the UK (MacKay et al. in Arthritis Rheum 46:632–639, 2001) and one from France (Cornelis et al. in Proc Natl Acad Sci USA 95:10746–10750, 1998). For each study, we obtained NPL scores by performing interval mapping (2 cM intervals) using GeneHunter2 (Kruglyak et al. in Am J Hum Genet 58:1347–1363, 1996; Markianos et al. in Am J Hum Genet 68:963–977, 2001). The marker maps differed among the three consortium groups, therefore, the marker maps were aligned after the interval mapping was completed and the NPL scores that were within 1 cM of each other were combined using the method of Loesgen et al. (Genet Epidemiol 21(Suppl 1):S142–S147, 2001) by calculating the weighted average of the NPL score. This approach avoids some problems in analysis encountered by using GeneHunter2 when some markers in the sample are not genotyped. This procedure provided marginal evidence (P<0.05) of linkage on chromosome 1, 2, 5 and 18, strong evidence (P<0.01) on chromosomes 8 and 16, and overwhelming evidence in the HLA region of chromosome 6.  相似文献   

14.
DNA fragments containing argK-tox clusters and their flanking regions were cloned from the chromosomes of Pseudomonas syringae pathovar (pv.) actinidiae strain KW-11 (ACT) and P. syringae pv. phaseolicola strain MAFF 302282 (PHA), and then their sequences were determined. Comparative analysis of these sequences and the sequences of P. syringae pv. tomato DC3000 (TOM) (Buell et al., Proc Natl Acad Sci USA 100:10181–10186, 2003) and pv. syringae B728a (SYR) (Feil et al., Proc Natl Acad Sci USA 102:11064–11069, 2005) revealed that the chromosomal backbone regions of ACT and TOM shared a high similarity to each other but presented a low similarity to those of PHA and SYR. Nevertheless, almost-identical DNA regions of about 38 kb were confirmed to be present on the chromosomes of both ACT and PHA, which we named “tox islands.” The facts that the GC content of such tox islands was 6% lower than that of the chromosomal backbone regions of P. syringae, and that argK-tox clusters, which are considered to be of exogenous origin based on our previous studies (Sawada et al., J Mol Evol 54:437–457, 2002), were confirmed to be contained within the tox islands, suggested that the tox islands were an exogenous, mobile genetic element inserted into the chromosomes of P. syringae strains. It was also predicted that the tox islands integrated site-specifically into the homologous sites of the chromosomes of ACT and PHA in the same direction, respectively, wherein 34 common gene coding sequences (CDSs) existed. Furthermore, at the left end of the tox islands were three CDSs, which encoded polypeptides and had similarities to the members of the tyrosine recombinase family, suggesting that these putative site-specific recombinases were involved in the recent horizontal transfer of tox islands. Electronic Supplementary Material Electronic Supplementary material is available for this article at and accessible for authorised users.  相似文献   

15.
Huey and Slatkin’s (Q Rev Biol 51:363–384, 1976) cost–benefit model of lizard thermoregulation predicts variation in thermoregulatory strategies (from active thermoregulation to thermoconformity) with respect to the costs and benefits of the thermoregulatory behaviour and the thermal quality of the environment. Although this framework has been widely employed in correlative field studies, experimental tests aiming to evaluate the model are scarce. We conducted laboratory experiments to see whether the common lizard Zootoca vivipara, an active and effective thermoregulator in the field, can alter its thermoregulatory behaviour in response to differences in perceived predation risk and food supply in a constant thermal environment. Predation risk and food supply were represented by chemical cues of a sympatric snake predator and the lizards’ food in the laboratory, respectively. We also compared males and postpartum females, which have different preferred or “target” body temperatures. Both sexes thermoregulated actively in all treatments. We detected sex-specific differences in the way lizards adjusted their accuracy of thermoregulation to the treatments: males were less accurate in the predation treatment, while no such effects were detected in females. Neither sex reacted to the food treatment. With regard to the two main types of thermoregulatory behaviour (activity and microhabitat selection), the treatments had no significant effects. However, postpartum females were more active than males in all treatments. Our results further stress that increasing physiological performance by active thermoregulation has high priority in lizard behaviour, but also shows that lizards can indeed shift their accuracy of thermoregulation in response to costs with possible immediate negative fitness effects (i.e. predation-caused mortality).  相似文献   

16.
The Protein Kinase C family of enzymes is a group of serine/threonine kinases that play central roles in cell-cycle regulation, development and cancer. A key step in the activation of PKC is translocation to membranes and binding of membrane-associated activators including diacylglycerol (DAG). Interaction of novel and conventional isotypes of PKC with DAG and phorbol esters occurs through the two C1 regulatory domains (C1A and C1B), which exhibit distinct ligand binding selectivity that likely controls enzyme activation by different co-activators. PKC has also been implicated in physiological responses to alcohol consumption and it has been proposed that PKCα (Slater et al. J Biol Chem 272(10):6167–6173, 1997; Slater et al. Biochemistry 43(23):7601–7609, 2004), PKCε (Das et al. Biochem J 421(3):405–413, 2009) and PKCδ (Das et al. J Biol Chem 279(36):37964–37972, 2004; Das et al. Protein Sci 15(9):2107–2119, 2006) contain specific alcohol-binding sites in their C1 domains. We are interested in understanding how ethanol affects signal transduction processes through its affects on the structure and function of the C1 domains of PKC. Here we present the 1H, 15N and 13C NMR chemical shift assignments for the Rattus norvegicus PKCδ C1A and C1B proteins.  相似文献   

17.
Advances in fluorescent labeling of cells as measured by flow cytometry have allowed for quantitative studies of proliferating populations of cells. The investigations (Luzyanina et al. in J. Math. Biol. 54:57–89, 2007; J. Math. Biol., 2009; Theor. Biol. Med. Model. 4:1–26, 2007) contain a mathematical model with fluorescence intensity as a structure variable to describe the evolution in time of proliferating cells labeled by carboxyfluorescein succinimidyl ester (CFSE). Here, this model and several extensions/modifications are discussed. Suggestions for improvements are presented and analyzed with respect to statistical significance for better agreement between model solutions and experimental data. These investigations suggest that the new decay/label loss and time dependent effective proliferation and death rates do indeed provide improved fits of the model to data. Statistical models for the observed variability/noise in the data are discussed with implications for uncertainty quantification. The resulting new cell dynamics model should prove useful in proliferation assay tracking and modeling, with numerous applications in the biomedical sciences.  相似文献   

18.
Three species of the genus Teratorhabditis (Osche, 1952) Dougherty, 1953 collected from sewage and manure samples of North India are described. The species T. andrassyi Tahseen & Jairajpuri (1988) synonymised by Sudhaus (1991) has been reinstated and is characterized by oviparous females having bluntly rounded lips with labial sensilla not raised beyond labial contour; lip margins and axils heavily cuticularised; three lines in lateral field; considerably wide and tubular stoma having swollen metastegostomal walls with prismatic inner lining bearing five teeth on each plate; basal bulb with usually single haustrulum; tail conoid with a terminal spike; eggs with ridged shells and males with 40–45% distally-fused spicules and a smooth, non-indented bursa having slender papillae in 2/4 + p + 3 configuration. Other populations identified as T. synpapillata and T. palmarum Gerber and Giblin-Davis (1990) are reported for the first time from India. An identification key to species is provided. Relationships within the genus are discussed. Electronic supplementary material Supplementary material is available for this article at and accessible for authorised users Handling editor: K. Martens  相似文献   

19.
Increasing evidence supports the idea that endemic avian and mammalian predators have profoundly impacted primate populations in Madagascar (Goodman, S. M. Predation on lemurs. In S. M. Goodman, & J. P. Benstead (Eds.), The natural history of Madagascar (pp. 1221–1228). Chicago: University of Chicago Press, (2003).). The role in regulating lemur populations of the 3 introduced mammalian carnivorans —small Indian civets (Viverricula indica, Desmarest 1804), domestic dogs (Canis lupus familiaris, Linnaeus 1758), and invasive wildcats (Felis silvestris, Schreber 1775)— is less clear, but recent evidence suggests that the latter 2 are becoming important predators of diurnal lemurs. We report evidence for invasive wildcat predation on sifaka (Propithecus verreauxi verreauxi) in Parcel 1 at Beza Mahafaly Special Reserve, Madagascar, including skeletal remains of apparent Propithecus sifaka victims, observations of wildcat predatory behavior, and behavioral responses of the lemurs in the presence of wildcats.  相似文献   

20.
ATP, the ‘universal biological energy currency’, is synthesized by utilizing energy either from oxidation of fuels or from light, via the process of oxidative and photo-phosphorylation respectively. The process is mediated by the enzyme F1F0-ATP synthase, using the free energy of ion gradients in the final energy catalyzing step, i.e., the synthesis of ATP from ADP and inorganic phosphate (Pi). The details of the molecular mechanism of ATP synthesis are among the most important fundamental issues in biology and hence need to be properly understood. In this work, a role for anions in making ATP has been found. New experimental data has been reported on the inhibition of ATP synthesis at nanomolar concentrations by the potent, specific anion channel blockers 4,4′-diisothiocyanostilbene-2, 2′-disulphonic acid (DIDS) and tributyltin chloride (TBTCl). Based on these inhibition studies, attention has been drawn to anion translocation (in addition to proton translocation) as a requirement for ATP synthesis. The type of inhibition has been quantified and an overall kinetic scheme for mixed inhibition that explains the data has been evolved. The experimental data and the type of inhibition found have been interpreted in the light of the torsional mechanism of energy transduction and ATP synthesis (Nath J Bioenerg Biomembr 42:293–300, 2010a; J Bioenerg Biomembr 42:301–309, 2010b). This detailed and unified mechanism resolves long-standing problems and inconsistencies in the first theories (Slater Nature 172:975–978, 1953; Williams J Theor Biol 1:1–17, 1961; Mitchell Nature 191:144–148, 1961; Mitchell Biol Rev 41:445–502, 1966), makes several novel predictions that are experimentally verifiable (Nath Biophys J 90:8–21, 2006a; Process Biochem 41:2218–2235, 2006b), and provides us with a new and fruitful paradigm in bioenergetics. The interpretation presented here provides intelligent answers to the unexplained existing results in the literature. It is shown that mechanistic interpretation of the experimental data requires substantial addition to available conceptual foundations such that present concepts, theories, and mechanisms must be revised.  相似文献   

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