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1.
Food selection in folivorous primates has been hypothesized to be correlated with leaf chemistry. To test this hypothesis,
we conducted a 5-month study on Presbytis entellusin a moist deciduous forest in the Rajaji National Park,Uttar Pradesh, India. The study period covered two seasons, winter and spring. We used the percentage time spent feeding on
each food item as an index of food selection, which we estimated from group scan data collected from one study group for 6
days each month. We estimated the selection ratio for each item as the ratio of time spent feeding to availability. We estimated
food availability from vegetation sampling and phenological data in the home range of the study group. We estimated crude
protein (CP), acid detergent fiber (ADF) and tannins in mature and young leaves of 12 major food species in the laboratory.
Food selection is positively correlated with CP in winter and negatively correlated with ADF in both seasons. It also is correlated
with CPJADF ratio, but to a lesser extent than the best predictor in winter and spring. Selection ratio is not correlated
with CP and ADF in both seasons. It is probable that the inclusion of other factors, such as micronutrients,condensed tannins, and digestibility, might give a better prediction of food selection. 相似文献
2.
During 2000 research on the pharmacology of marine chemicals involved investigators from Australia, Brazil, Canada, Egypt, France, Germany, India, Indonesia, Israel, Italy, Japan, the Netherlands, New Zealand, Phillipines, Singapore, Slovenia, South Korea, Spain, Sweden, Switzerland, United Kingdom, and the United States. This current review, a sequel to the authors 1998 and 1999 reviews, classifies 68 peer-reviewed articles on the basis of the reported preclinical pharmacologic properties of marine chemicals derived from a diverse group of marine animals, algae, fungi, and bacteria. Antibacterial, anticoagulant, antifungal, antimalarial, antiplatelet, antituberculosis, or antiviral activity was reported for 35 marine chemicals. An additional 20 marine compounds were shown to have significant effects on the cardiovascular and nervous system, and to possess anti-inflammatory or immunosuppressant properties. Finally, 23 marine compounds were reported to act on a variety of molecular targets and thus could potentially contribute to several pharmacologic classes. Thus, as in 1998 and 1999, during 2000 pharmacologic research with marine chemicals continued to contribute potentially novel chemical leads to the ongoing global search for therapeutic agents in the treatment of multiple disease categories. 相似文献
3.
G. C. HURTT † S. FROLKING ‡ M. G. FEARON B. MOORE E. SHEVLIAKOVA§¶ S. MALYSHEV§¶ S. W. PACALA§ R. A. HOUGHTON 《Global Change Biology》2006,12(7):1208-1229
To accurately assess the impacts of human land use on the Earth system, information is needed on the current and historical patterns of land‐use activities. Previous global studies have focused on developing reconstructions of the spatial patterns of agriculture. Here, we provide the first global gridded estimates of the underlying land conversions (land‐use transitions), wood harvesting, and resulting secondary lands annually, for the period 1700–2000. Using data‐based historical cases, our results suggest that 42–68% of the land surface was impacted by land‐use activities (crop, pasture, wood harvest) during this period, some multiple times. Secondary land area increased 10–44 × 106 km2; about half of this was forested. Wood harvest and shifting cultivation generated 70–90% of the secondary land by 2000; permanent abandonment and relocation of agricultural land accounted for the rest. This study provides important new estimates of globally gridded land‐use activities for studies attempting to assess the consequences of anthropogenic changes to the Earth's surface over time. 相似文献
4.
Analysis of the far-ultraviolet circular dichroism spectrum of bovine blood coagulation factor IX reveals the presence of approximately 14% helical structures 26% -sheets, 20% -turns, and 40% coils. These values are essentially the same for the activation products of this zymogen, factor IXa and factor IXa. Similar analysis for bovine factor X permits calculation of these secondary structural as approximately 11% helices, 31% -structures, 22% -turns, and 36% random structures. Bovine prothrombin contains approximately 12% helical structures, 35% -structures, 24% -turns, and 29% coils. None of these values is substantially altered as a result of increase of thepH from 7.4 to 10.5, or upon addition of Ca2+ to a concentration of at least 20 mM. Analysis of the near-ultraviolet spectra of factor IX and prothrombin suggests that several aromatic amino acid residues and the disulfide bond present in their -carboxyglutamic acid-containing regions are exposed to solvent and are perturbed by the abovepH adjustment and Ca2+ addition. Similar effects are observed in the case of factor X; in addition, the Trp residue at the amino terminus of the heavy chain appears to be influenced by the abovepH alteration. The results reported in this paper show that these vitamin K-dependent blood coagulation proteins are similar in their ordered secondary structures, which are dominated by -sheets and -turns. Their overall secondary structures are not influenced by Ca2+ binding and are stable to alkalinepH changes. However, these same environmental alterations appear to be effective probes of aromatic residues in the -carboxyglutamic acid regions. 相似文献
5.
Carmen Martin Ruiz Clotilde Duquenne Dominique Treton Anick Lefvre Catherine Finaz 《Molecular reproduction and development》1998,49(3):286-297
LB5 antibody was selected from a monoclonal antibody (mAb) library directed against human sperm proteins. LB5 mAb detected the corresponding protein SOB3 in the neck region and the flagellum of most live ejaculated sperm while it labelled, in addition, the acrosome of about 10–20% of spermatozoa. The percentage of LB5 acrosome-stained sperm was significantly correlated with the percentages of either spontaneous or A23187-induced acrosome-reacted sperm. While SOB3 could not be detected in the testis, it appeared in spermatozoa from the corpus epididymis segment. LB5 mAb impaired neither sperm motion parameters, acrosomal reaction triggering, nor sperm binding to zona-free hamster oocytes. By contrast, LB5 Fab fragments (200 μg/ml) inhibited sperm binding to human zonae pellicidae by 35.7%. If sperm were induced to acrosome react with A23187 prior to LB5 treatment, the inhibitory effect shifted to 59.9%, while no significant effect was observed following A23187 incubation alone. Western blotting of human sperm and cauda epididymis extracts revealed two bands of 18 and 19 kDa. While no cross-reaction was observed with other tested organs, a similar 18-kDa band was revealed in erythocytes and one of 19 kDa in B-lymphocytes. No cross-reactivity could be evidenced in any animal sperm analyzed. SOB3 was first separated in a 17- to 20-kDa preparative electrophoresis fraction and finally purified by isoelectrofocusing according to its pI of 9.8. These results suggest that SOB3 is localized under the outer acrosomal membrane, that it participates in secondary sperm binding to the zona pellucida, and that it shares homologies with the immune system. Mol. Reprod. Dev. 49:286–297, 1998. © 1998 Wiley-Liss, Inc. 相似文献
6.
《Bioorganic & medicinal chemistry letters》2020,30(11):127145
Two new chlorinated secondary metabolites, saccharochlorines A and B (1 and 2), were isolated from the saline cultivation of a marine-derived bacterium Saccharomonospora sp. (KCTC-19160). The chemical structures of the saccharochlorines were elucidated by 2D NMR and MS spectroscopic data. Saccharochlorines A and B (1 and 2) exhibit weak inhibition of β-secretase (BACE1) in biochemical inhibitory assay, but they induced the release of Aβ (1–40) and Aβ (1–42) in H4-APP neuroglial cells. This discrepancy might be derived from the differences between the cellular and sub-cellular environments or the epigenetic stimulation of BACE1 expression. 相似文献
7.
The pigmentation of 23 species of Neospongiococcum Deason was studied in the stationary phase of nitrogen-limited cultures on agar with or without glucose or in liquid medium. Fourteen species gradually developed an orange or brown color, and in all, secondary carotenoids were detected by thin-layer chromatography. Among these, the keto-carotenoids echinenone, canthaxanthin and esterified astaxanthin were identified, although the last named was not always present. When aging on glucose agar, the remaining nine species developed only a yellow-green or yellow color and a pronounced tendency to bleach. In these, the aforementioned keto-carotenoids were lacking, and β-carotene and lutein lucre dominant. From this study it is not clear whether secondary carotenoid formation is species-specific in Neospongiococcum. 相似文献
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Camptotheca acuminata is a main source of the anti-cancer drug camptothecin (CPT). In this species, several studies have observed non-glandular trichomes (NGTs) and glandular trichomes (GTs). It has been assumed that GTs contain CPT, yet this has not been proven and no information is available on the accumulation of other secondary metabolites. The objective of this study was to describe the morphology, distribution and structure of C. acuminata trichomes and to investigate the chemical nature of the substances secreted by GTs. Light and fluorescence microscope, scanning electron microscope (SEM) and transmission electron microscope (TEM) were used to determine the morphology, distribution and structure of GTs and NGTs. Thin layer chromatography (TLC) and high-performance liquid chromatography (HPLC) analyses were carried out to confirm the presence of CPT in GTs, and histochemical tests were performed to investigate the presence of other secondary metabolites. C. acuminata possesses two types of GTs (GT1 and GT2), which differ in terms of their morphology, pattern of distribution and accumulated substances. The chemical analyses demonstrated that both GT1 and GT2 accumulate CPT. Histochemical analysis showed that phenols accumulate in the vacuole of GT2s. No isoprenoids were detected in GTs. 相似文献
11.
Abstract From a secondary tumor in a bean stem we have isolated a Gram-negative bacteria, named by us T.2. These bean stems had crown gall tumors induced by the ATV strain of Agrobacterium tumefaciens . This bacterium was classified as belonging to the genus Aeromonas and possesses the capacity of inducing overgrowths in plants, synthesizing indole acetic acid (IAA). The codified phenotypic characteristics of bacterium T.2. via the Ti-plasmid of A. tumefaciens , such as opine utilization and sensitivity to agrocin 84, have been studied. Neither octopine nor nopaline is utilized by T.2. and it is resistant to agrocin 84, whereas the strain ATV of A. tumefaciens utilizes nopaline, and is sensitive to agrocin 84. 相似文献
12.
Mariano Jordi Muria‐Gonzalez Yit‐Heng Chooi Susan Breen Peter S. Solomon 《Molecular Plant Pathology》2015,16(1):92-107
The Dothideomycetes represents a large and diverse array of fungi in which prominent plant pathogens are over‐represented. Species within the Cochliobolus, Alternaria, Pyrenophora and Mycosphaerella (amongst others) all cause diseases that threaten food security in many parts of the world. Significant progress has been made over the past decade in understanding how some of these pathogens cause disease at a molecular level. It is reasonable to suggest that much of this progress can be attributed to the increased availability of genome sequences. However, together with revealing mechanisms of pathogenicity, these genome sequences have also highlighted the capacity of the Dothideomycetes to produce an extensive array of secondary metabolites, far greater than originally thought. Indeed, it is now clear that we appear to have only scratched the surface to date in terms of the identification of secondary metabolites produced by these fungi. In the first half of this review, we examine the current status of secondary metabolite research in the Dothideomycetes and highlight the diversity of the molecules discovered thus far, in terms of both structure and biological activity. In the second part of this review, we survey the emerging techniques and technologies that will be required to shed light on the vast array of secondary metabolite potential that is encoded within these genomes. Experimental design, analytical chemistry and synthetic biology are all discussed in the context of how they will contribute to this field. 相似文献
13.
G. Winfield Fairchild 《International Review of Hydrobiology》1983,68(3):339-350
Population changes of Sida crystallina, a filter feeding microcrustacean which attaches to aquatic macrophytes, were examined in Cochran Lake, Michigan during June and July, 1979. Population estimates were derived from organisms present in 10 samples of leaves of the water lily Nymphaea odorata collected every 3 days. Population densities of Sida responded both to food and predation by fish. Declines in average clutch size were associated with decreasing phytoplankton biomass and the increasing dominance of colonial green and blue-green algae, but were not significantly influenced by the densities of invertebrates on the plants. Largemouth bass fry (Micropterus salmoides) dramatically reduced the numbers of Sida and altered the age structure of the population in late June. 相似文献
14.
Abstract.— We studied sequence variation in 16S rDNA in 204 individuals from 37 populations of the land snail Candidula unifasciata (Poiret 1801) across the core species range in France, Switzerland, and Germany. Phylogeographic, nested clade, and coalescence analyses were used to elucidate the species evolutionary history. The study revealed the presence of two major evolutionary lineages that evolved in separate refuges in southeast France as result of previous fragmentation during the Pleistocene. Applying a recent extension of the nested clade analysis (Templeton 2001), we inferred that range expansions along river valleys in independent corridors to the north led eventually to a secondary contact zone of the major clades around the Geneva Basin. There is evidence supporting the idea that the formation of the secondary contact zone and the colonization of Germany might be postglacial events. The phylogeographic history inferred for C. unifasciata differs from general biogeographic patterns of postglacial colonization previously identified for other taxa, and it might represent a common model for species with restricted dispersal. 相似文献
15.
LIFANG LI WEIBO SONG ALAN WARREN MANN KYOON SHIN ZIGUI CHEN DAODE JI PING SUN 《The Journal of eukaryotic microbiology》2008,55(5):448-456
ABSTRACT. In order to re‐evaluate the systematics of sessilid peritrich ciliates, small subunit (SSU) rRNA gene sequences were determined for 12 species belonging to five genera: Vorticella, Pseudovorticella, Epicarchesium, Zoothamnium, and Zoothamnopsis. Phylogenetic trees were deduced using Bayesian inference, maximum parsimony, and maximum likelihood methods. The phylogenetic analyses suggest that (1) sessilids which have stalks with continuous myonemes that contract in a zig‐zag fashion form a separate clade from those which have stalks that contract independently and in a spiral fashion, supporting the separation of the family Zoothamniidae from the family Vorticellidae and (2) Epicarchesium and Pseudovorticella, both of which have reticulate silverline systems, are more closely related to each other than to other vorticellids, suggesting that differences in the silverline system (i.e. transverse vs. reticulate) may be the result of genuine evolutionary divergence among sessilid peritrichs. However, the newly sequenced Zoothamnopsis sinica, which has a reticulate silverline pattern, nests within the unresolved Zoothamnium species that have transverse silverline patterns. Thus, there were at least two evolutions of the reticulate silverline pattern character state from a plesiomorphic transverse state in the peritrichid ciliates. The molecular work demonstrates the genus Zoothamnium to be paraphyletic in relation to morphological studies, and suggests that Astylozoon, Opisthonecta, and Vorticella microstoma possibly share a SSU rRNA secondary structure in the helix E10‐1 region. 相似文献
16.
SUMMARY 1. Population dynamics and production of Jesogammarus annandalei , an endemic amphipod in Lake Biwa, were examined from April 1997 to June 1998. The life cycle of this species was 1 year with the new generation beginning in early autumn. They preferred low temperature (<12 °C) and their spatial distribution varied seasonally and accordingly.
2. In deep water, the abundance of J. annandalei ranged from 200 to 63 000 m−2 and decreased towards summer and the biomass (0.01∼3.6 g C m−2 ) was on average comparable that of zooplankton. The density was much higher than that recorded by a study conducted 35 years ago.
3. Individual growth rate of this amphipod was high in winter and spring but decreased in summer. Annual production of J. annandalei (6.2 g C m−2 year−1 ) was only 2% of primary production but was at the higher end of the range reported for amphipods in oligo- and mesotrophic lakes.
4. These results are consistent with the view that Lake Biwa is becoming more eutrophic, with a consequent decrease in the abundance of predatory fish in the profundal zone. 相似文献
2. In deep water, the abundance of J. annandalei ranged from 200 to 63 000 m
3. Individual growth rate of this amphipod was high in winter and spring but decreased in summer. Annual production of J. annandalei (6.2 g C m
4. These results are consistent with the view that Lake Biwa is becoming more eutrophic, with a consequent decrease in the abundance of predatory fish in the profundal zone. 相似文献
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Human phospholemman (PLM) is a 72-residue protein, which is expressed at high density in the cardiac plasma membrane and in various other tissues. It forms ion channels selective for K+, Cl-, and taurine in lipid bilayers and colocalizes with the Na+/K+-ATPase and the Na+/Ca2+-exchanger, which may suggest a role in the regulation of cell volume. Here we present the first structural data based on synthetic peptides representing the transmembrane domain of PLM. Perfluoro-octaneoate-PAGE of reconstituted proteoliposomes containing PLM reveals a tetrameric homo-oligomerization. Infrared spectroscopy of proteoliposomes shows that the PLM peptide is completely alpha-helical, even beyond the hydrophobic core residues. Hydrogen/deuterium exchange experiments reveal that a core of 20-22 residues is not accessible to water, thus embedded in the lipid membrane. The maximum helix tilt is 17 degrees +/- 2 degrees obtained by attenuated total reflection infrared spectroscopy. Thus, our data support the idea of ion channel formation by the PLM transmembrane domain. 相似文献
19.
Solution secondary structures of three synthetic cationic peptides, currently used in antisense oligonucleotide delivery into living cells, have been analyzed by means of circular dichroism (CD) and Raman scattering in different buffers as a function of concentration and time. All three peptides are of minimalist conception, i.e., formed by only two types of amino acids (leucine: L and lysine: K). Two of these peptides contain 15 aminoacids: N(ter)- KLLKLLLKLLLKLLK (L(10)K(5)), N(ter)-KLKLKLKLKLKLKLK (L(7)K(8)), and the third one has only 9 residues: N(ter)-KLKLKLKLK (L(4)K(5)). The conformational behavior of the 15-mers in pure water differs considerably one from another. Although both of them are initially disordered in the 50-350 microM range, L(10)K(5) gradually undergoes a disordered to alpha-helix transition for molecular concentrations above 100 microM. In all other solvents used, L(10)K(5) adopts a stable alpha-helical conformation. In methanol and methanol/Tris mixture, nonnative alpha-helices can be induced in both KL-alternating peptides, i.e., L(7)K(8) and L(4)K(5). However, in major cases and with a time delay depending on peptide concentration, beta-like structures can be gradually formed in both solutions. In PBS and methanol/PBS mixture, the tendency for L(7)K(8) and L(4)K(5) is to form structures belonging to beta-family. A discussion has been undertaken on the effect of counterions as well as their nature in the stabilization of ordered structures in both KL-alternating peptides. 相似文献
20.
Makarenko S. P. Trufanov V. A. Putilina T. E. 《Russian Journal of Plant Physiology》2002,49(3):326-331
The secondary structure of prolamins, the storage proteins of wheat (Triticum aestivum L.), rye (Secale cereale L.), and barley (Hordeum vulgare L.), was studied by infrared (IR) spectroscopy. The secondary structure of wheat gliadin was characterized by a high content of unordered conformations of polypeptide chains (64–67%) and a low content of short -helical regions (4–5%). Elongated conformations, formed by poly-L-proline II helices (61 and 53%) and -turns (15 and 19%), predominated in rye secalins and barley hordeins. Prolamin proteins of cereal crops also contained -sheet structure regions comprising 9–12% of the polypeptide chains. 相似文献