首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
This study revises the morphological characters of both sexes of Kuhl’s pipistrelle, including external, cranial and dental characters. This study also establishes a baseline for the diet of this insectivorous bat species across a variety of habitats in the Nile Valley, where diets have never before been investigated. Our findings of the stomach contentswere not significantly affected despite the different habitats from which the samples were collected. The three most common insect taxa recovered were Hymenoptera, Lepidoptera and Coleoptera. The percentage volume of insect orders in the diet of Kuhl’s bat (63 stomachs) consisted of 29% of Hymenoptera, 9% of Coleoptera, 27% of Lepidoptera, 32% unknown materials and unexpected thing of these insectivorous bats was the presences of 3% fruits. A single order did not dominate the diet of this specie because Hymenoptera was the most fed insect orders by frequency of occurrence 87.3%, Lepidoptera by 74.6%, Coleoptera 36.5% and fruits in 4.8% of samples. Also, they may also be fed by other insect orders, as unknown materials were found in all samples.  相似文献   

2.
Five novel antimicrobial peptides (temporin-LK1, rugosin-LK1, rugosin-LK2, gaegurin-LK1, and gaegurin-LK2) are purified and characterized from Kuhl’s wart frog skin secretions, Limnonectes kuhlii. They share obvious similarity to temporin, rugosin, and gaegurin antimicrobial peptide family, respectively. Their amino acid sequences were determined by Edman degradation and mass spectrometry, and further confirmed by cDNA cloning. Nine cDNA sequences encoding precursors of these five purified antimicrobial peptides and other four hypothetical antimicrobial peptides were cloned from the skin cDNA library of L. kuhlii. The deduced precursors are composed of a predicted signal peptide, an acidic spacer peptide, and a mature antimicrobial peptide. Most of them showed strong antimicrobial activities against Gram-positive and Gram-negative bacteria and fungi. The current work identified and characterized three families of antimicrobial peptides from L. kuhlii skins and confirmed that the genus of Limnonectes amphibians share similar antimicrobial peptide families with the genus of Rana amphibians. In addition, a unique antimicrobial peptide (temporin-LK1) with 17 residues including four phenylalanines, which is significantly different from other temporins (16 residues, one or two phenylalanines), was identified in this work. Such unique structure might provide novel template or leading structure to design antimicrobial agents.  相似文献   

3.
Goiti  Urtzi  Vecin  Patricia  Garin  Inazio  Saloña  Marta  Aihartza  Jose R. 《Acta theriologica》2003,48(4):457-468
The trophic ecology of Kuhl’s pipistrellePipistrellus kuhlii (Kuhl, 1817) was investigated monthly from May to October 1999. Nine insect and two arachnid orders were identified in faeces and classified in 24 different categories. The most frequently occurring prey categories were Culicidae, Lepidoptera, Chironomidae/Ceratopogonidae, Hymenoptera, unidentified Brachycera, Tipulidae and unidentified Coleoptera in decreasing order. Other categories exhibited seasonal importance, such as the coleopteranRhizotrogus sp. Prey availability was evaluated monthly using Malaise traps in known feeding areas. Bats preyed selectively through a temporarily changing pattern. Some taxa constituted an important part of the diet and were positively selected either monthly or in most of the months. Many of them were the largest prey featuring in the diet and changes of their relative profitability across time would determine their selection index. The small size of some prey categories as well asP.kuhlii’s morphofunctional constraints relative to flight and echolocation could explain their underexploitation or rejection. Our results suggest thatP. kuhlii could be regarded as a ‘selective opportunist’ species.  相似文献   

4.
The distribution of Vulpes cana in the extreme eastern Sahara is described on the basis of new photographic and sight records, as well as a recently acquired specimen from south-eastern Egypt. The proven range of this elusive fox now extends about 1000 km south into Africa along the Red Sea coastal mountains. The proven and predicted distribution ranges of this fox are discussed. Its phylogeography and evolutionary relationship to other foxes of the region are gleaned from analysis of mitochondrial cytochrome b DNA sequence and are discussed in light of climatic and paleogeographic history of the area. The results show that the species could have initially moved into Africa during the Pliocene-Pleistocene transition period when several land bridges occurred across the Gulf of Suez. More recent land bridges between the mountains of the Sinai Peninsula and the Eastern Desert of Egypt seem to have developed and disappeared several times during the Pleistocene, possibly allowing genetic exchange between V. cana populations in these two areas. The last of this population exchange and genetic flow between the two areas seems to have ended some 14,000 years ago when the present Gulf of Suez inundation took place.  相似文献   

5.
6.
7.
8.
The nineteenth century theologian, author and poet Charles Kingsley was a notable populariser of Darwinian evolution. He championed Darwin’s cause and that of honesty in science for more than a decade from 1859 to 1871. Kingsley’s interpretation of evolution shaped his theology, his politics and his views on race. The relationship between men and apes set the context for Kingsley’s consideration of these issues. Having defended Darwin for a decade in 1871 Kingsley was dismayed to read Darwin’s account of the evolution of morals in Descent of Man. He subsequently distanced himself from Darwin’s conclusions even though he remained an ardent evolutionist until his death in 1875.  相似文献   

9.
Membrane-induced disorder-to-helix transition of α-synuclein, a presynaptic protein, has been implicated in a number of important neuronal functions as well as in the etiology of Parkinson’s disease. In order to obtain structural insights of membrane-bound α-synuclein at the residue-specific resolution, we took advantage of the fact that the protein is devoid of tryptophan and incorporated single tryptophan at various residue positions along the sequence. These tryptophans were used as site-specific markers to characterize the structural and dynamical aspects of α-synuclein on the negatively charged small unilamellar lipid vesicles. An array of site-specific fluorescence readouts, such as the spectral-shift, quenching efficiency and anisotropy, allowed us to discern various features of the conformational rearrangements occurring at different locations of α-synuclein on the lipid membrane. In order to define the spatial localization of various regions of the protein near the membrane surface, we utilized a unique and sensitive indicator, namely, red-edge excitation shift (REES), which originates when a fluorophore is located in a highly ordered micro-environment. The extent of REES observed at different residue positions allowed us to directly identify the residues that are localized at the membrane-water interface comprising a thin (∼ 15 Å) layer of motionally restrained water molecules and enabled us to construct a dynamic hydration map of the protein. The combination of site-specific fluorescence readouts allowed us to unravel the intriguing molecular details of α-synuclein on the lipid membrane in a direct model-free fashion. Additionally, the combination of methodologies described here are capable of distinguishing subtle but important structural alterations of α-synuclein bound to different negatively charged lipids with varied head-group chemistry. We believe that the structural modulations of α-synuclein on the membrane could potentially be related to its physiological functions as well as to the onset of Parkinson’s diseases.  相似文献   

10.
Several developing countries seek to build knowledge-based economies by attempting to expand scientific research capabilities. Characterizing the state and direction of progress in this arena is challenging but important. Here, we employ three metrics: a classical metric of productivity (publications per person), an adapted metric which we denote as Revealed Scientific Advantage (developed from work used to compare publications in scientific fields among countries) to characterize disciplinary specialty, and a new metric, scientific indigeneity (defined as the ratio of publications with domestic corresponding authors) to characterize the locus of scientific activity that also serves as a partial proxy for local absorptive capacity. These metrics—using population and publications data that are available for most countries–allow the characterization of some key features of national scientific enterprise. The trends in productivity and indigeneity when compared across other countries and regions can serve as indicators of strength or fragility in the national research ecosystems, and the trends in specialty can allow regional policy makers to assess the extent to which the areas of focus of research align (or not align) with regional priorities. We apply the metrics to study the Middle East and North Africa (MENA)—a region where science and technology capacity will play a key role in national economic diversification. We analyze 9.8 million publication records between 1981–2013 in 17 countries of MENA from Morocco to Iraq and compare it to selected countries throughout the world. The results show that international collaborators increasingly drove the scientific activity in MENA. The median indigeneity reached 52% in 2013 (indicating that almost half of the corresponding authors were located in foreign countries). Additionally, the regional disciplinary focus in chemical and petroleum engineering is waning with modest growth in the life sciences. We find repeated patterns of stagnation and contraction of scientific activity for several MENA countries contributing to a widening productivity gap on an international comparative yardstick. The results prompt questions about the strength of the developing scientific enterprise and highlight the need for consistent long-term policy for effectively addressing regional challenges with domestic research.  相似文献   

11.
We studied the seasonal activity pattern of the Kuhl’s pipistrelle Pipistrellus kuhlii in eight sites of the Bou Hedma National Park, central Tunisia, from June 2010 to June 2011, using both mistnetting and acoustic bat detection. Pipistrelles were captured all year-round only at water bodies. Captures peaked in late spring and early autumn. Pregnant females were observed from March to June, lactating females only in June, and flying juveniles from June to August. Echolocation calls and buzzes were recorded in all sites throughout the year. However, activity varied significantly among months and sites. Activity peaked in June and September after a noteworthy decline in August; the minimum was recorded in December and January. Bats mainly foraged at water bodies and around streetlamps. This result supports the previously reported major role of water bodies for bats in arid environments. Bats also foraged in the open acacia forest in summer, during the flowering period of Acacia Acacia tortilis raddiana. The steppe was the least used habitat. Social calls were mainly recorded in autumn around streetlamps, suggesting a swarming behaviour. Despite being a common bat species in the area, P. kuhlii should deserve conservation efforts that would benefit other bat species.  相似文献   

12.

Background

Although Parkinson’s disease (PD) is a progressive neurodegenerative disorder characterized primarily by motor symptoms, PD patients, at all stages of the disease, can experience cognitive dysfunction. However, the relationships between cognitive and motor symptoms and specific demographic characteristics are not well defined, particularly for patients who have progressed to requiring dopaminergic medication.

Objective

To examine relationships between motor and cognitive symptoms and various demographic factors in mild to moderate, PD patients requiring anti-PD medication.

Methods

Cognitive function was assessed in 94 subjects with a variety of neuropsychological tests during baseline evaluations as part of an experimental treatment study. Data were analyzed in relation to Unified Parkinson’s Disease Rating Scale motor scores and demographic variables.

Results

Of the UPDRS subscores analyzed, posture/balance/gait was associated with the highest number of adverse cognitive outcomes followed by speech/facial expression, bradykinesia, and rigidity. No associations were detected between any of the cognitive performance measures and tremor. Motor functioning assessed in the “off” condition correlated primarily with disease duration; neuropsychological performance in general was primarily related to age.

Conclusion

In PD patients who have advanced to requiring anti-PD therapies, there are salient associations between axial signs and cognitive performance and in particular, with different aspects of visuospatial function suggesting involvement of similar circuits in these functions. Associations between executive functions and bradykinesia also suggest involvement similar circuits in these functions.  相似文献   

13.
14.
《Fungal biology》2020,124(12):983-1003
Witches' broom caused by Moniliophthora perniciosa is the main disease of cacao (Theobroma cacao) in Brazil. The fungus is known to occur on other host families and these populations have been addressed in the literature as biotypes: C (Malvaceae); H (Malpighiaceae); L (Bignoniaceae) and S (Solanaceae). No complete elucidation of the phylogenetic relationships of isolates obtained from this disparate host range appears in the literature. One member of H (ex Heteropterys acutifolia) has been described as a distinct species. But should other biotypes be also recognized as distinct taxa? In the present study, a survey yielding 24 isolates of M. perniciosa from ten hosts and covering a wide range of geographic regions in Brazil was undertaken. These isolates were compared with those from T. cacao using three DNA regions for the phylogenetic analyses: ITS, LSU and RPB1. Morphology was also examined. All isolates in this study were found to belong to M. perniciosa, including the population from H. acutifolia, formerly treated as Moniliophthora brasiliensis but reduced here to a synonym of M. perniciosa. This species ranged from pathogenic to a previously unreported occurrence as a non-pathogenic endophyte in the Atlantic rainforest tree Allophylus edulis (Sapindaceae). M. perniciosa was recorded on a range of solanaceous hosts (16 species) over a wide variety of ecosystems. The ecological and evolutionary significance of these novel findings are discussed.  相似文献   

15.
16.
17.
α-Synuclein (α-syn) is a 140-residue protein of unknown function, involved in several neurodegenerative disorders, such as Parkinson's disease. Recently, the possible interaction between α-syn and polyunsaturated fatty acids has attracted a strong interest. Indeed, lipids are able to trigger the multimerization of the protein in vitro and in cultured cells. Docosahexaenoic acid (DHA) is one of the main fatty acids (FAs) in cerebral gray matter and is dynamically released following phospholipid hydrolysis. Moreover, it has been found in high levels in brain areas containing α-syn inclusions in patients affected by Parkinson's disease. Debated and unsolved questions regard the nature of the molecular interaction between α-syn and DHA and the effect exerted by the protein on the aggregated state of the FA. Here, we show that α-syn is able to strongly interact with DHA and that a mutual effect on the structure of the protein and on the physical state of the lipid derives from this interaction. α-Syn acquires an α-helical conformation in a simple two-state transition. The binding of the protein to the FA leads to a reduction of the size of the spontaneously formed aggregated species of DHA as well as of the critical aggregate concentration of the lipid. Specifically, biophysical methods and electron microscopy observations indicated that the FA forms oil droplets in the presence of α-syn. Limited proteolysis experiments showed that, when the protein is bound to the FA oil droplets, it is initially cleaved in the 89-102 region, suggesting that this chain segment is sufficiently flexible or unfolded to be protease-sensitive. Subsequent proteolytic events produce fragments corresponding to the first 70-80 residues that remain structured and show high affinity for the lipid. The fact that a region of the polypeptide chain remains accessible to proteases, when interacting with the lipid, suggests that this region could be involved in other interactions, justifying the ambivalent propensity of α-syn towards folding or aggregation in the presence of FAs.  相似文献   

18.
Alzheimer’s disease (AD) is the leading cause of dementia. The two histopathological markers of AD are amyloid plaques composed of the amyloid-β (Aβ) peptide, and neurofibrillary tangles of aggregated, abnormally hyperphosphorylated tau protein. The majority of AD cases are late-onset, after the age of 65, where a clear cause is still unknown. However, there are likely different multifactorial contributors including age, enviornment, biology and genetics which can increase risk for the disease. Genetic predisposition is considerable, with heritability estimates of 60–80%. Genetic factors such as rare variants of TREM2 (triggering receptor expressed on myeloid cells-2) strongly increase the risk of developing AD, confirming the role of microglia in AD pathogenesis. In the last 5 years, several studies have dissected the mechanisms by which TREM2, as well as its rare variants affect amyloid and tau pathologies and their consequences in both animal models and in human studies. In this review, we summarize increases in our understanding of the involvement of TREM2 and microglia in AD development that may open new therapeutic strategies targeting the immune system to influence AD pathogenesis.  相似文献   

19.
20.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号