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1.
The European mink ( Mustela lutreola ) is a small mammal, which belongs to the Mustelidae family ( Carnivora) . Earlier, the range of distribution of this species encompassed much of the European continent. During the 20th century, the numbers of European mink declined and the range of its distribution became reduced to three fragmented populations; today this species faces extinction. The urgent necessity for effective conservation efforts to protect the European mink is accepted by the governmental organizations as well as scientific communities of most European countries. In this paper, the reasons for the disappearance of European mink are reviewed and results of past conservation efforts based on captive breeding and reintroduction programmes are critically evaluated in the broad context of modern concepts of conservation genetics and reproductive biology. The data recently obtained on the reproduction and pre-implantation development of European mink and the prospects of incorporation of modern reproductive technologies into the conservation programme of this species are discussed. 相似文献
3.
The structure of the sperm of Liza dumerili was studied by light microscopy and scanning and transmission electron microscopy.The sperm have a kidney-shaped nucleus. The “hilus” faces posteriorly and the proximal centriole is situated within the nuclear pit. Nuclear rotation takes place during spermiogenesis and the sperm are therefore related to those of other teleosts showing Type I spermiogenesis. No acrosome is evident. The midpiece is small but distinct and contains four spherical mitochondria. The flagellum enters the midpiece eccentrically and the axoneme runs obliquely towards the distal centriole to which it is connected. The flagellum conforms to the 9 + 2 flagellar pattern. 相似文献
7.
活性氧(ROS)是自然界普遍存在的含氧化合物的总称,它对哺乳动物早期胚胎发育具有不良影响。本文综述了活性氧对哺乳动物早期胚胎发育的影响以及它与胚胎体外发育阻滞的内在联系,对深入探讨哺乳动物早期胚胎体外发育阻滞的机理具有一定的意义。 相似文献
8.
Cylicospirura (Cylicospirura) felineus (Chandler, 1925) Sandground, 1933 is reported from a cat in South Africa for the first time. The nematode was present in a gastric parasitic nodule in a male domestic cat, and three males were recovered as well as the anterior parts of three and the posterior parts of two gravid females. The heads of two specimens of undetermined sex were also found. Part of the removed parasitic nodule was processed for histopathological examination. The parasitic nodule was located in the submucosa and slightly expanded into the muscular layer. In its centre were small necrotic areas containing debris of inflammatory cells, adult nematodes and numerous bacterial colonies. Neutrophils, eosinophils, plasma cells and lymphocytes, as well as fibroblasts, were the predominant cell types. The serosal surface of the stomach remained unaffected. Some comparative morphological as well as ecological data concerning Cylicospirura (Cylicospirura) Vevers, 1922 in other feline hosts, mainly from Australia, India and North America, are included. 相似文献
9.
Nham is a traditional Thai fermented pork sausage. The major ingredients of Nham are ground pork meat and shredded pork rind. Nham has been reported to be contaminated with Salmonella spp., Staphylococcus aureus, and Listeria monocytogenes. Therefore, it is a potential cause of foodborne diseases for consumers. A Hazard Analysis and Critical Control Points (HACCP) generic model has been developed for the Nham process. Nham processing plants were observed and a generic flow diagram of Nham processes was constructed. Hazard analysis was then conducted. Other than microbial hazards, the pathogens previously found in Nham, sodium nitrite and metal were identified as chemical and physical hazards in this product, respectively. Four steps in the Nham process have been identified as critical control points. These steps are the weighing of the nitrite compound, stuffing, fermentation, and labeling. The chemical hazard of nitrite must be controlled during the weighing step. The critical limit of nitrite levels in the Nham mixture has been set at 100-200 ppm. This level is high enough to control Clostridium botulinum but does not cause chemical hazards to the consumer. The physical hazard from metal clips could be prevented by visual inspection of every Nham product during stuffing. The microbiological hazard in Nham could be reduced in the fermentation process. The critical limit of the pH of Nham was set at lower than 4.6. Since this product is not cooked during processing, finally, educating the consumer, by providing information on the label such as "safe if cooked before consumption", could be an alternative way to prevent the microbiological hazards of this product. 相似文献
10.
Routine clinical examination of the chest is described. The basic principles of viewing X-ray plates are mentioned. The conditions of the canine and feline thorax dealt with are mostly those which can be confirmed radiologically during life. The major points of differential diagnosis of each condition are dealt with within groups determined by some cardinal clinical sign. For convenience each condition is dealt with only under one groupheading, although it may have additional signs of some of the other groups. The groups and conditions are as follows: Gross Dyspnoea Hydrothorax Pyothorax Pneumothorax Diaphragmatic hernia Pneumonia Cough Distemper Tuberculosis Secondary lung tumour Filaroides osleri infestation of the trachea Kennel cough Feline influenza Tiring on exercise Cardiac valvular disease Congenital cardiac disease Difficulty in swallowing Oesophageal foreign body Feline oesophageal annular carcinoma Oesophageal diverticulum Mega-oesophagus (Achalasia) Oesophageal dilatation associated with vascular anomalies of the right aortic arch. 相似文献
12.
Extract Madam:– In June 1985, a juvenile common bluetongue skink, Tiliqua scincoides, died at Wellington Zoological gardens. This animal was one of the progeny of three lizards imported from Melbourne Zoo in 1982. They joined a T. scincoides (origin unknown) already in residence at Wellington Zoo. Other juveniles had died on occasions but there were no records indicating whether the cause had been established. 相似文献
14.
The brooding sea anemone Sagartia ornata is reported from South Africa for the first time and is redescribed. The species is abundant intertidally in Langebaan Lagoon, where it attaches to stones shal lowly buried in sediment. It is probably a recent intro duction from Europe. 相似文献
15.
The freshwater snails belonging to the genus Melanoides Olivier, 1804 are widespread across tropical regions of the world and endemic species have evolved in the African Lakes Malawi, Mweru and Tanganyika. The endemic Melanoides species of Lake Malawi have been investigated several times during the last century, due to their large conchological variation, but no unambiguous answer regarding the number of species has been given. The phylogenetic relationship between morphs or genetic clones of Melanoides in Lake Malawi was inferred by phylogenetic analyses of DNA sequence data from the mitochondrial genes 16S and COI. Additional sequences from GenBank were included to investigate the relationship to other morphs from different parts of the world. For the first time, a putative secondary structure was developed for a partial region of 16S in this genus to identify the variability of the secondary structure in stems and loops. The molecular analyses indicated that several genetic clones exist in Lake Malawi and that M. tuberculata is a paraphyletic taxon. It is not clear from the results whether invasions or dispersals account for the complex situation in Lake Malawi. The basal position of M. admirabilis, endemic to Lake Tanganyika, in the inferred phylogeny indicates that Africa might be the origin of the genus. The results further indicate that three major clades of Melanoides, consisting of several genetic clones, are present in Lake Malawi; one clade consisting of invasive M. tuberculata, another of native M. tuberculata and a third consisting of the M. polymorpha- complex. It appears as if the unique development of morphs within the Melanoides genus in Lake Malawi has evolved primarily by divergence of genetic clones instead of species differentiation. 相似文献
16.
Abstract Infections of Myxobolus corneus (species nova) are described from the eyes of bluegills Lepomis macrochirus from Mt. Olive, Illinois. Individual eyes had up to 36 trophozoites (0.250.8 mm in diameter) distributed peripherally around the corneal margin with few beyond the level of the inner edge of the iris. Mature spores were oval in front view and measured 8.0–10.5 um long and 6.5–9.0 μm wide. Spores of M. corneus resembled most closely those of Myxobolus cartilaginis (Hoffman, Putz, and Dunbar, 1965). Statistical comparison of spores of the two species with similarly prepared paratype material revealed that M. corneus has significantly smaller polar capsules than does M. cartilaginis. Myxobolus corneus is the fourth species of Myxobolus to be reported from bluegills in North America. 相似文献
17.
Oligochaetes living in the Mijares River close to the Sitjar reservoir, and polychaetes from the brackish and marine waters of a channel flowing into the Mediterranean Sea, both in the province of Castellón (Spain), were examined for the presence of actinosporea. An aurantiactinomyxon was isolated from 60 specimens of the oligochaete Branchiura sowerbyi collected from the river, but no actinospores were isolated from 160 polychaetes collected from the sea channel. The aurantiactinospores were detected by the cell-well plate method. The detected species are not identical with any of the aurantiactinomyxon forms hitherto described in the literature. This is the first report on the occurrence of an actinosporea in Spanish waters. 相似文献
19.
This study evaluated the presence and seasonal activity of free-living ticks in remaining marsh areas by the Paraná river, in Brazil. Eight field trips (once per season) for collection of ticks were performed during 2 years. Using CO2 traps, dragging, and visual inspection of vegetation, five free-living tick species were collected, in the following order of abundance: Amblyomma cajennense, Amblyomma dubitatum, Amblyomma triste, Amblyomma coelebs, and Amblyomma nodosum. The seasonal pattern of A. cajennense was characterized by the highest peaks for adult ticks in the summer/spring months, for nymphs in the winter and for larvae in the autumn and winter. A. dubitatum and A. triste presented similar seasonal patterns characterized by peaks of adult ticks in the autumn. Nymphs of A. dubitatum peaked in the winter of the first year and in the winter/spring of the second year. A. triste was the only species to be collected in significantly higher numbers in the marsh than in surrounding drier areas such as forest patches. Among domestic animals living close the marsh areas, horses were infested by Anocentor nitens, A. cajennense, and Boophilus microplus, bovines were infested solely by B. microplus, and dogs were infested by Rhipicephalus sanguineus. Adults of A. triste showed to be well adapted to the marsh environment. This result, at least partially, explains local previous observations on the association of A. triste with marsh deer, as this vertebrate host inhabits mainly the marsh area. 相似文献
20.
The Pacific echiuran species Anelassorhynchus porcellus (Fisher, 1948) was collected from the intertidal rocky shores at Perriers Rock and Isipingo Beach on the KwaZulu-Natal coast. This is the first known record of this species from South African waters. Anelassorhynchus porcellus, originally described by Fisher (1948) from several specimens collected in tidal pools south of Honolulu Harbour, Hawaii was later recorded and described by Edmonds (1960) from specimens collected from Heron Island, Queensland. The discovery of this species from the east coast of southern Africa considerably extends its geographical range. After closer examination of additional specimens of Anelassorhynchus gangae Biseswar, 1984 collected from the Kwazulu-Natal coast it is proposed that this species be recognized as a junior synonym of A. porcellus. Anelassorhynchus porcellus is redescribed and some of the taxonomic characters are reviewed. 相似文献
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