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 0 毫秒
1.
Encephalitozoon hellem is a new human microsporidian isolated from corneal biopsies and conjunctival scrapings of three AIDS patients and cultured in Madin Darby canine kidney (MDCK) cells. Encephalitozoon hellem and Encephalitozoon cuniculi display different protein profiles with sodium dodecyl sulfate-polyacrylamide gel electrophoresis and unique antibody binding patterns with murine antisera against Western blots of each organism. Developmental stages of E. hellem in culture are similar to E. cuniculi. Meronts are 1.3–2.7 μm in diameter, develop within a parasitophorous vacuole adjacent to the vacuolar membrane, divide by binary fission, and contain one or two discrete nuclei. Sporonts measure 2 × 3 μm, separate from the vacuolar membrane, and have a thickened outer membrane. Sporoblasts display a tri-layered wall and possess the earliest recognized polar filaments. Mature spores measure 1 × 1.5 μm and are more electron-dense than other stages. Each spore contains a single nucleus, a polar tubule with four to nine coils, thin electron-dense exospore and thick, electron-lucent endospore. Although E. hellem and E. cuniculi differ biochemically and immunologically, their fine structure and development are indistinguishable.  相似文献   

2.
Ten polymorphic microsatellite loci were isolated from the cooperatively breeding and sexually dichromatic Eclectus parrot (Eclectus roratus). Nine loci were in Hardy–Weinberg equilibrium and unlinked. One locus, Ero1, was presumed to be sex‐linked since females, the heterogametic sex, were all homozygous, whereas 72% of males were heterozygous. A DNA database search revealed that Ero8 is probably an independent isolation of the microsatellite locus AgGT83 of the parrot Amozona guildingii. With high heterozygosity (0.41–0.89) and number of alleles (two to 13), these loci should prove useful for investigating the mating system of these unusual Australasian parrots.  相似文献   

3.
Despite the absence of pronounced changes in day length, there is considerable climatological seasonality in the tropics. Its expression can be complex like in the monsoon climate of the Indian Ocean Islands. The land mass distribution on both sides of the equator leads to seasonal changes in prevailing wind direction and seasonal patterns in food supply, which are distinct between different coasts. Here we assess that territory quality of the Seychelles warbler, endemic to the small island of Cousin peaks during the South East monsoon (April to September) in most of the island. The Southeastern wind-exposed side is exceptional by being generally poor and having slightly increased food supply in the opposite season (NW monsoon; October to March). In response, the warblers in most territories breed primarily during the SE season, while on the SE shores they tend to breed in both seasons. The result is a semi-annual periodicity in breeding. Individual pairs can breed in 6 months intervals. In the poorer territories on the SE shore most of them indeed do this, while in the richer central habitats most pairs restrict themselves to the best (SE) season. The frequency of breeding thereby increases with territory quality in the SE season, and decreases with quality in the NW season. Withholding from breeding in the NW season despite the high food supply may have long-term advantages for the birds occupying the richer habitat. Such flexible adjustment of seasonality to local circumstances requires not only an immediate response mechanism but also access to accurate information about time of year. The subtle sensitivity of tropical songbirds to photoperiod, demonstrated so convincingly by Eberhard Gwinner (Biological rhythms, Hokkaido University Press, Sapporo, pp19–40, 2005), may well have profound adaptive meaning in taking temporally optimized reproductive decisions in response to both food and time of year.
Jan KomdeurEmail:
  相似文献   

4.
作者于2014和2015年在广西西南部的西大明山自治区级自然保护区研究冠斑犀鸟(Anthracoceros albirostris)的繁殖生物学特征,以直接观察法或红外相机共观察5巢犀鸟,2014年2巢,2015年3巢。研究显示,西大明山的冠斑犀鸟在每年4月下旬至5月下旬开始营巢繁殖,雌鸟进入巢洞并在雄鸟协助下自封在其内,期间与幼鸟完全依靠雄鸟喂食。雄鸟带回巢的食物中,数量上有超过80%是果实。雌鸟在封巢期间完成换羽,并和幼鸟在7月中旬至8月中旬破巢而出,封巢时间为89 d和93 d(n=2),繁殖成功率为100%(n=4),平均出巢幼鸟为(2.3±0.5)只(2或3只,n=4)。营巢树与人工林/林下作物的平均距离为87 m(0~210 m,n=3),其中,两棵生长在当地人经常使用的山路旁。营巢树种分别为南酸枣(Choerospondias axillaris)及金叶树(Chrysophyllum lanceolatum),营巢树平均胸径为73.7 cm(72.0~75.0 cm,n=3),巢洞高度为7.8 m和9.0 m(n=2)。其中两棵营巢树在2014年和2015年的繁殖季均被重...  相似文献   

5.
This study emphasizes the importance of free-living coatis as a potential source of microsporidian infection for humans living in large cities. We found 19 (31.7%) positive results among 60 fecal samples analyzed by PCR-based analysis and the Gram-Chromotrope staining technique (11.7% were positive for Encephalitozoon cuniculi, 6.7% for E. intestinalis, 6.7% for E. hellem, and 6.7% for Enterocytozoon bieneusi). Only 5 (8.4%) urine samples tested positive for E. cuniculi as assessed by the two techniques.  相似文献   

6.
A postcranial skeleton of a representative of the palaeognathous Lithornithidae (Aves) is described from the Middle Eocene of Messel in Germany. The specimen is slightly smaller than Lithornis plebius from which it, however, differs in limb bone proportions. It constitutes the latest fossil record of the Lithornithidae in Europe, whose only other Middle Eocene record is a fragmentary tibiotarsus from North America.  相似文献   

7.
ABSTRACT. Microsporidia are obligate intracellular protozoan parasites that can cause opportunistic infections in AIDS patients. Species from five genera of microsporidia are presently known to infect man. One species, Septata intestinalis originally was detected in stool specimens of individuals with chronic diarrhea and subsequently was found to disseminate to the kidneys, lungs, and nasal sinuses. This organism has since been reclassified as Encephalitozoon and in this study, we report the culture of Encephalitozoon intestinalis from a bronchoalveolar lavage specimen and a nasal mucus aspirate of two AIDS patients living in the USA. The bronchoalveolar and nasal microsporidian isolates grew in several continuous cell lines including RK-13, MDCK, HT-29, Caco-2, Vero, and 1047. Transmission electron microscopy of the clinical and cell culture specimens revealed that the new isolates appeared to be E. intestinalis based on morphology and growth of organisms in septated membrane-bound parasitophorous vacuoles. The new E. intestinalis isolates were characterized and compared with the first isolated E. intestinalis that was cultured from stool to confirm their identity and to determine if there existed any minor differences, as seen in the closely related Encephalitozoon cuniculi strains. By the methods of sodium dodecyl sulfate-polyacrylamide gel electrophoresis staining for proteins and carbohydrates, Western blot immunodetection, and polymerase chain reaction-based methods with restriction endonuclease digestion, double-stranded DNA heteroduplex mobility shift analysis, and DNA sequencing of the ribosomal DNA intergenic spacer region, the new isolates were identical to each other and to the reference isolate of E. intestinalis. In addition, with any of these methods, the E. intestinalis organisms could be distinguished from the three E. cuniculi strains, Encephalitozoon hellem, and Vittaforma corneae, which is important for diagnostics, therapeutic strategies, and epidemiology.  相似文献   

8.
9.
Abstract: We describe well‐preserved remains of the Pelagornithidae (bony‐toothed birds) from the middle Eocene of Belgium, including a sternum, pectoral girdle bones and humeri of a single individual. The specimens are tentatively assigned to Macrodontopteryx oweni Harrison and Walker, 1976 , which has so far only been known from the holotype skull and a referred proximal ulna. Another species, about two times larger, is represented by an incomplete humerus and tentatively identified as Dasornis emuinus ( Bowerbank, 1854 ). The fossils provide critical new data on the osteology of the pectoral girdle of bony‐toothed birds. For the first time, the sternum of one of the smaller species is preserved, and this bone exhibits a more plesiomorphic morphology than the recently described sternum of the giant Miocene taxon Pelagornis. The coracoid resembles that of the Diomedeidae (albatrosses) in overall morphology, but because bony‐toothed birds lack apomorphies of the Procellariiformes, the similarities are almost certainly owing to convergence. Bony‐toothed birds were often compared with the ‘Pelecaniformes’ by previous authors, who especially made comparisons with the Sulidae (gannets and boobies). However, the coracoid distinctly differs from that of extant ‘pelecaniform’ birds, and the plesiomorphic presence of a foramen nervi supracoracoidei as well as the absence of a well‐delimited articulation facet for the furcula supports a position outside the Suloidea, the clade to which the Sulidae belong.  相似文献   

10.
We evaluated the effects of Plasmodium relictum (lineage P-SGS1), which is a host generalist, to five species of passerine birds. Light infection of P. relictum was isolated from a naturally infected adult reed warbler Acrocephalus scirpaceus. The parasites were inoculated to naive juveniles of the chaffinch Fringilla coelebs, common crossbill Loxia curvirostra, house sparrow Passer domesticus, siskin Spinus spinus and starling Sturnus vulgaris. Susceptibility of these birds to the infection of P. relictum was markedly different. This parasite developed in birds belonging to the Fringillidae and Passeridae but the starlings (Sturnidae) were resistant. Only 50% of experimental house sparrows were susceptible to the infection. The intensity of parasitemia varied markedly inside and between different susceptible bird species. There were no effects of the infection on body mass or temperature of experimentally infected birds. Infection of P. relictum leads to the significant decrease of haematocrit value and hypertrophy of spleen and liver in heavily infected common crossbills and siskins. This study shows that infection of the same lineage of P. relictum causes diseases of different severity in different avian hosts; that might have different evolutionary consequences and should be taken in consideration in conservation projects.  相似文献   

11.
Adults, nymphs, larvae and eggs of Gallilichus jonesi sp. n. are described. These mites inhabit the quills of large wing and tail feathers of the megapode Alectura lathami Gray, where they appear to consume the spongy medulla inside the quill. This is the first record of Gallilichus for Australia, and the first observation of quill mites associated with the Megapodiidae. Two nymphal morphologies of G. jonesi were observed and are presumed to represent male and female, but because pharate adults were not found, definitive assignment of morphs to sexes was not possible. The only other species in the genus Gallilichus occurs in the feathers of domestic chickens. The implications of these host-associations for elucidating relationships between the megapodes and other galliform birds are discussed.  相似文献   

12.
This study depicts how captive kea, New Zealand parrots, which are not known to use tools in the wild, employ a stick-tool to retrieve a food reward after receiving demonstration trials. Four out of six animals succeeded in doing so despite physical (beak curvature) and ecological (no stick-like materials used during nest construction) constraints when handling elongated objects. We further demonstrate that the same animals can thereafter direct the functional end of a stick-tool into a desired direction, aiming at a positive option while avoiding a negative one.  相似文献   

13.
We describe here a sensitive assay method for lysosulfatide (sulfogalactosylsphingosine) in human tissues using HPLC. The method involves extraction of lipids, saponification, isolation using a C18 Sep-Pak column, derivatization with o-phthalaldehyde, and detection of the fluorescent lysosulfatide using HPLC. In control subjects, a small amount of lysosulfatide was detected in the cerebral white matter (9-35 pmol/mg of protein), spinal cord (35 pmol/mg of protein), sciatic nerve (14 pmol/mg of protein), and kidney (approximately 2 pmol/mg of protein) but not in the cerebral gray matter and liver. A marked accumulation of the lipid was noted in tissues from six patients with metachromatic leukodystrophy (MLD). The concentration of lysosulfatide was high in the cerebral white matter, spinal cord, and sciatic nerve (223-1,172 pmol/mg of protein). Even in the cerebral gray matter, kidney, and liver, where lysosulfatide was hardly detected in the control sample, a considerable amount (3-45 pmol/mg of protein) accumulated in MLD patients. The concentration and distribution pattern of lysosulfatide were similar to those of galactosylsphingosine (psychosine) accumulated in patients with Krabbe disease. Therefore, the accumulation of lysosulfatide may explain the demyelination in patients with MLD, as is the case with Krabbe disease.  相似文献   

14.
This survey was conducted in two protected areas in Nigeria to genetically identify individual lions and to determine the genetic variation within and between the populations. We used faecal sample DNA, a non-invasive alternative to the risky and laborious task of taking samples directly from the animals, often preceded by catching and immobilization. Data collection in Yankari Game Reserve (YGR) spanned through a period of five years (2008 –2012), whereas data in Kainji Lake National Park (KLNP) was gathered for a period of three years (2009, 2010 and 2012). We identified a minimum of eight individuals (2 males, 3 females, 3 unknown) from YGR and a minimum of ten individuals (7 males, 3 females) from KLNP. The two populations were found to be genetically distinct as shown by the relatively high fixation index (FST  = 0.17) with each population exhibiting signs of inbreeding (YGR FIS  = 0.49, KLNP FIS  = 0.38). The genetic differentiation between the Yankari and Kainji lions is assumed to result from large spatial geographic distance and physical barriers reducing gene flow between these two remaining wild lion populations in Nigeria. To mitigate the probable inbreeding depression in the lion populations within Nigeria it might be important to transfer lions between parks or reserves or to reintroduce lions from the zoos back to the wild.  相似文献   

15.
We studied the limiting factors for brood size in the kestrel, Falco tinnunculus, by measuring parental effort in natural broods of different size and parental response to manipulation of food satiation of the brood. Parental effort was quantified as total daily time spent in flight, and total daily energy expenditure, from all-day observations. During nestling care males with different natural brood sizes (4 to 7 chicks), spent an average of 4.75 h · d?1 in flight independent of brood size, and expended an average total daily energy of 382 kJ · d?1. Due to a higher flight-hunting yield (mammal-prey caught per hour hunting), males with larger natural broods were able to provision their broods with the same amount of food (mainly Microtus arvalis) per chick (62.6 g · d?1), with the same effort as males with smaller broods. This provisioning rate was close to the mean feeding rate of hand-raised chicks in the laboratory, that were fed ad libitum, (66.8 g · d?1 · chick?1). Our food deprivation experiments revealed that male kestrels strongly respond to food shortage in the nest. In the older nestling phase males on average increased their daily rate of food delivery to the nest as a response to experimental food deprivation by almost three times to 646.4 g · d?1, by increasing their flight activity level from 4.46 to 8.41 h · d?1. This increased energy expenditure was sustained, for as long as eleven days, by increasing the metabolizable energy intake up to what is presumed to be the maximum rate. Even under considerable experimental food stress (chicks not being satiated due to continuous removal of delivered food by the observers) about half of the available daylight time remained unused for foraging. We conclude 1) that the mean daily energy expenditure of males during nestling care — to which clutch size is apparently initially adjusted — is well below the maximum they are able to sustain and 2) that the energy expenditure they can sustain under extremely high nestling demand is not set by the available time for foraging or the available energy in the environment. Thus the birds normally operate well below their presumed maximum, and only during food shortage, e.g., as caused by our experiments, do they increase activity up to this maximum. Therefore we conclude that the kestrels have costs other than energy expenditure, such as parental survival, that are involved in the increased “cost” of parental effort. We discuss possible generalisations about existing energetic limitations during parental care in altricial birds. From published estimates of daily energy expenditure during parental care (DEEpar) in 30 different bird species we derived the equation: DEEpar = 14.26 kg0.65 Watt. This relationship differs significantly in slope (T = 2.49; p > 0.02) from the allometric equation for the maximum rate of energy assimilation (DMEmax) as provided by Kirkwood (1983): DMEmax = 19.82 kg0.72 Watt. In smaller species (ca. 25 g) DEEpar about equals DMEmax, while in the larger species (ca. 10 kg) DEEpar represents only about 60% of the predicted DMEmax. This suggests that limitations in parental effort are more frequently set by the maximum sustainable energy intake in the smaller species than in larger species. Our allometric equations for DEEpar suggests that the relation between BMR, estimated using the equations of Aschoff and Pohl (1970), and the observed parental energy expenditure, is such that on average bird parents work at a daily level somewhere between 3 and 4 times BMR.  相似文献   

16.
Problems with parasitic infections are common in zoological gardens and circuses. In some animals it can lead to several disorders such as systemic disease, reproductive disorders (abortions and neonatal mortality), and even to death if severe illness is untreated. Thus, the aim of this study was to evaluate the prevalence of three common parasites in 74 animals from three zoos, and four circuses in Southern Italy. Antibodies to Toxoplasma gondii, Neospora caninum, and Encephalitozoon cuniculi were detected in 51%, 12%, and 20% of animals, respectively. Co‐infections of T. gondii and N. caninum were reported in seven animals (9%) and co‐infection of T. gondii and E. cuniculi in one animal. T. gondii, N. caninum and E. cuniculi seroprevalence differed in type of diet (P ≤ 0.0001; P ≤ 0.037 and P ≤ 0.004, respectively). T. gondii and E. cuniculi seroprevalence also differed in animal families (P ≤ 0.0001) and according to type of housing (P ≤ 0.003), respectively. Statistical differences were not found in other characteristics (gender, age, country of birth, origin, and contact with cats or dogs). This is the first serological study focusing on protozoan and microsporidian parasites in zoo and circus animals from Southern Italy and the first detection of antibodies to E. cuniculi in camels in Europe.  相似文献   

17.
中国梨2个自交不亲和新等位基因(S等位基因)的分子鉴定   总被引:9,自引:0,他引:9  
自交不亲和是显花植物的一种重要生殖生理现象,为探明中国梨的自交不亲和特性,对‘锦香’(Pyrus bretschneideri cv. Jinxiang)和‘鹅酥’(Pyrus bretschneideri cv. Esu)2个中国梨品种进行了基因组PCR特异扩增、S基因序列分析及田间杂交授粉试验。结果确定它们各含1个新S-RNA酶基因,分别命名为S37-和S38-RNase,GenBank序列号为DQ839238和DQ839239。生物信息学分析结果表明,S37-和S38-RNA酶的推导氨基酸序列与S1-至S36-RNA酶36个梨S基因具有相同的、高度保守的C1和C2区,但其高变区与S1-至S36-RNA酶差异较大,其中与S15的差异最小,只有3个氨基酸不同。在推导的氨基酸水平上,S37与S38有96%的序列相似性,但两者与S15的相似性更高,皆为98%,与S32的相似性最低,都只有63%;S37和S38的内含子较大,分别为786bp和723bp,与S15的777bp大小接近。最后,经分析验证确定‘锦香’和‘鹅酥’的S基因型分别为S34S37和S15S38。  相似文献   

18.
2010年2月12-13日,在西藏日喀则樟木镇海拔2070m及1900m处的公路旁分别观察并拍摄到一种鸟类.根据观察资料及所拍照片,鉴定为黑颏穗鹛(Stachyris pyrrhops)(图1).经查阅文献(Zheng,2002;Zheng,2005)属鹟科(Turdinae)画鹛亚科(Timaliinae)穗鹛属(Stachyris)的中国鸟类新记录,特此报道.  相似文献   

19.
Two species of the holocentrid fish genusMyripristis are described as new from Japan, both with a single pair of tooth patches outside the gape at tip of lower jaw, the third anal spine longer than the fourth, and 28–29 lateral-line scales:M. kochiensis from Kashiwa-jima, Kochi Prefecture, previously misidentified asM. murdjan, is distinct in having small scales in axil of pectoral fins, 32–36 gill rakers, interorbital space 4.45–5.1 in head, and lower jaw not strongly projecting when mouth closed;M. greenfieldi, from the Ryukyu Islands and Ogasawara Islands to Kochi Prefecture, previously misidentified asM. woodsi andM. randalli, is distinct in lacking scales in the pectoral axil, having 35–52 cteni on largest body scales, 43–47 gill rakers, and longest dorsal spine 2.0–2.25 in head.  相似文献   

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