50 resultados para Lycaon Pictus
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Seven captive male African wild dogs (Lycaon pictus) weighing 25-32 kg each, were anesthetized by i.m. injection via hand syringe with a combination of 1.5 mg/kg ketamine, 40 mu g/kg medetomidine, and 0.05 mg/kg atropine. Following endotracheal intubation, each animal was connected to a bain closed-circuit system that delivered 1.5% isoflurane and 2 L/min oxygen. Atipamezole (0.1 mg/kg i.v.; 0.1 mg/kg i.m.) was given at the end of each procedure (60 min following injection of medetomidine/ketamine/atropine). Time to sternal recumbency was 5-8 min. Times to standing after atipamezole administration were 8-20 min. This anesthetic regimen was repeated on three separate occasions (September 2000, February 2002, and October 2002) on all males to perform electroejaculation procedures. Each procedure was < 80 min from injection to standing. Dogs showed excellent muscle relaxation during the procedures. Arterial blood samples were collected at 10-min intervals for blood gases in one procedure (September 2000). Separate venous samples were taken from each dog during each procedure for hematology and biochemistry. These values were within the normal range for this species. Arterial hemoglobin oxygen saturation (SpO2) and heart rate (HR) were monitored continuously in addition to other anesthesia monitoring procedures (body temperature, respiratory rate [RR], capillary refill time, blink response, pupil position, deep pain perception reflex). All dogs maintained relatively stable SpO2 profiles during monitoring, with a mean (+/- SD) SpO2 of 92% +/- 5.4%. All other physiological variables (HR, RR, body temperature, blood pressure) were within normal limits. Following each procedure, normal behavior was noted in all dogs. All the dogs were reunited into the pack at completion of their anesthetic procedures. An injectable medetomidine-ketamine-atropine combination with maintenance by gaseous isoflurane and oxygen provides an inexpensive, reliable anesthetic for captive African wild dogs.
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Most ecosystems have multiple predator species that not only compete for shared prey, but also pose direct threats to each other. These intraguild interactions are key drivers of carnivore community structure, with ecosystem-wide cascading effects. Yet, behavioral mechanisms for coexistence of multiple carnivore species remain poorly understood. The challenges of studying large, free-ranging carnivores have resulted in mainly coarse-scale examination of behavioral strategies without information about all interacting competitors. We overcame some of these challenges by examining the concurrent fine-scale movement decisions of almost all individuals of four large mammalian carnivore species in a closed terrestrial system. We found that the intensity of intraguild interactions did not follow a simple hierarchical allometric pattern, because spatial and behavioral tactics of subordinate species changed with threat and resource levels across seasons. Lions (Panthera leo) were generally unrestricted and anchored themselves in areas rich in not only their principal prey, but also, during periods of resource limitation (dry season), rich in the main prey for other carnivores. Because of this, the greatest cost (potential intraguild predation) for subordinate carnivores was spatially coupled with the highest potential benefit of resource acquisition (prey-rich areas), especially in the dry season. Leopard (P. pardus) and cheetah (Acinonyx jubatus) overlapped with the home range of lions but minimized their risk using fine-scaled avoidance behaviors and restricted resource acquisition tactics. The cost of intraguild competition was most apparent for cheetahs, especially during the wet season, as areas with energetically rewarding large prey (wildebeest) were avoided when they overlapped highly with the activity areas of lions. Contrary to expectation, the smallest species (African wild dog, Lycaon pictus) did not avoid only lions, but also used multiple tactics to minimize encountering all other competitors. Intraguild competition thus forced wild dogs into areas with the lowest resource availability year round. Coexistence of multiple carnivore species has typically been explained by dietary niche separation, but our multi-scaled movement results suggest that differences in resource acquisition may instead be a consequence of avoiding intraguild competition. We generate a more realistic representation of hierarchical behavioral interactions that may ultimately drive spatially explicit trophic structures of multi-predator communities.
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本文采用几何形态测量的方法对产自和政地区的鬣狗科Hyaenictitherium, Ictitherium, Adcrocuta和旁鬣狗科Dinocrocuta的材料进行研究,分析了这4个属保存完好的头骨标本的侧面形态。与东非大草原现生食肉动物的头骨整体形态分布的比较和分析表明,和政的鼬鬣狗(Ictitherium)和鬣型鼬鬣狗(Hyaenictitherium)的头骨形状分布介于现生斑鬣狗(Crocuta crocuta)、犬科猎狗(Lycaon pictus)和金豺(Canis aureus)之间,为二者似豺生态形态的解释提供了几何形态测量证据。再者,上述两属化石鬣狗的形状分布与现生斑鬣狗的幼年个体形状重叠,表明现生斑鬣狗头骨的发育机制可能是在鼬鬣狗祖先类型的异速生长规律基础上的持续发育,进而演化出现有的粗壮形态。此外,巨鬣狗(Dinocrocuta)和副鬣狗(Adcrocuta)的头骨形状与现生的斑鬣狗在几何形态测量空间内有普遍重叠的现象,指示了这些异时出现的种类具有相似的生态形态,因而可能占据相近的生态位。结果还显示巨鬣狗和斑鬣狗的幼年个体形状相近,以及两者从幼年到成年发育的形状变化过程也具有相似的规律。因而,巨鬣狗和斑鬣狗之间的趋同演化不仅表现在成年头骨的粗壮程度上,而且在幼年发育模式中也存在平行演化现象。现生发育学与行为生态学已经证实,相对其他大型食肉动物,现生斑鬣狗发育粗壮头骨形态的机制不是以增速生长,而是以延长发育期来实现的。由此推断,巨鬣狗的发育期有可能和现生鬣狗相当(35个月),也可能由于具有相对粗壮和巨大的头骨形态,其发育期会延长些。当然,这个新解释仍需要更多的化石数据和发育研究来证实。
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1. Hydatid cysts are found in more than 30 per cent of all cattle, sheep and goats in Kenya, but the disease is prevalent in man only in the semi-desert area of Turkana. Up to the time of the present investigation the life-cycle of the parasite in East Africa had not been studied, but it was suggested that wild carnivores, such as hyenas and jackals, might be the main hosts of the adult worms. 2. One hundred and forty-three carnivores, representing 23 species, have been examined. Echinococcus adults were found in 27 out of 43 domestic dogs (Canis familiaris), in three out of four hunting dogs (Lycaon pictus), in one out of nine jackals (Thos mesomelas), and in three out of 19 hyaenas (Crocuta crocuta). 3. A detailed morphological study was made of the Kenya material. After comparison with specimens from other parts of the world, it was concluded that the only species occurring in Kenya was E. granulosus, but it is possible that the minor morphological and biological differences are evidence of distinct strains. Further laboratory studies are necessary to compare the parasite from man and animals in different parts of Kenya with material from elsewhere. 4. A search was made for larval hydatids in 92 ungulates representing 18 species, and in a miscellaneous collection of nearly 2,000 rodents and primates representing a further 31 species. Only one animal was positive, a wildebeest (Gorgon taurinus). 5. The infections in the wild carnivores were all very light; only domestic dogs were heavily infected. It is concluded that the main cycle of transmission in Kenya is between dogs and domestic livestock. 6. Turkana tribesmen are the most heavily infected people in Kenya, either because the strain of parasite is more pathogenic to man in that area, or, more probably, because of the intimate contact between children and the large number of infected dogs. A particularly dangerous custom in the area is the use of dogs to clean the face and anal regions of babies when they vomit or have diarrhea. No satisfactory explanation can be given for the rarity of the disease in man in many of the other areas of Kenya where hydatids are very common in domestic animals. 7. The control of the disease will depend upon an active health-education campaign, together with the destruction of all unregistered dogs and improvement in meat hygiene.
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Disease in wildlife raises a number of issues that have not been widely considered in the bioethical literature. However, wildlife disease has major implications for human welfare. The majority of emerging human infectious diseases are zoonotic: that is, they occur in humans by cross-species transmission from animal hosts. Managing these diseases often involves balancing concerns with human health against animal welfare and conservation concerns. Many infectious diseases of domestic animals are shared with wild animals, although it is often unclear whether the infection spills over from wild animals to domestic animals or vice versa. Culling is the standard means of managing such diseases, bringing economic considerations, animal welfare and conservation into conflict. Infectious diseases are also major threatening processes in conservation biology and their appropriate management by culling, vaccination or treatment raises substantial animal ethics issues. One particular issue of great significance in Australia is an ongoing research program to develop genetically modified pathogens to control vertebrate pests including rabbits, foxes and house mice. Release of any self-replicating GMO vertebrate pathogen gives rise to a whole series of ethical questions. We briefly review current Australian legal responses to these problems. Finally, we present two unresolved problems of general importance that are exemplified by wildlife disease. First, to what extent can or should 'bioethics' be broadened beyond direct concerns with human welfare to animal welfare and environmental welfare? Second, how should the irreducible uncertainty of ecological systems be accounted for in ethical decision making?
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Dissertação mest., Biologia Marinha, Universidade do Algarve, 2006
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The present work is to understand the alterations of total Muscarinic and Muscarinic MI receptors in brain and pancreatic islets of Streptozotocin induced diabetic rats. The work focuses on the evaluation of the antihyperglycemic activity of aqueous extracts of Aegle marmelose and Costus pictus leaves in vivo and the changes in the total Muscarinic and Muscarinic MI receptors during diabetes and after the treatment with insulin. The insulin secretory activity of Aegle marmelose and Costus pictus leaf extracts and the effect of cholinergic receptor agonist were investigated in vitro using rat primary pancreatic islet culture. Muscarinic MI receptor kinetics and gene expression during diabetes and regulation of insulin secretion by Aegle marmelose and Costus pie/us leaf extracts will help us to elucidate the role of Muscarinic and Muscarinic MI receptors in hyperglycemia and the regulatory activity of these plant extracts on insulin secretion through Muscarinic receptors.
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We present morphological and natural history data on Epipedobates pictus and three additional taxa currently regarded as synonyms of the former: Epipedobates braccatus, E. flavopictus, and E. hahneli. Topotypes of the four species were examined. Morphological data on tadpoles and adults, in addition to distribution patterns and vocalizations, indicate that the four taxa represent distinct species. Two groups are evident within them: (1) the slender-bodied, Amazonian E. hahneli with small flash marks on the thighs and a low-finned tadpole, and (2) the robust bodied, almost extra-Amazonian E. braccatus, E. flavopictus, and E. pictus with large flash marks on the thighs and tadpoles with fins of moderate height.
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Presents morphological and natural history data on Epipedobates pictus and three additional taxa currently regarded as synonyms of the former: Epipedobates braccatus, E. flavopictus and E. hahneli. Morphological data on tadpoles and adults, in addition to distribution patterns and vocalizations, indicate that the four taxa represent distinct species. -from Authors
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A dissertação foi elaborada no formato de artigos, separados em capítulos, conforme formatação do Programa de Pós-Graduação em Ecologia Aquática e Pesca da Universidade Federal do Pará. E todos os experimentos foram conduzidos sob licença ambiental (IBAMA/MMA nº 02018.00729/06-36). O capítulo geral contém uma breve introdução sobre os caranguejos de água doce, com ênfase para os Trichodactylidae. Em seguida, apresentam-se os objetivos e a metodologia comum utilizada no trabalho. Os resultados foram agrupados em quatro capítulos, abordando aspectos da biologia de duas espécies de caranguejos dulcícolas presentes na baía do Guajará, Pará, Brasil: Sylviocarcinus devillei H. Milne-Eduards, 1853 e Sylviocarcinus pictus (H. Milne-Eduards, 1853). No primeiro capítulo foi investigada a estrutura populacional (razão sexual e estrutura em tamanho), bem como a distribuição dos caranguejos em relação aos locais de coleta e aos fatores abióticos (temperatura e salinidade). O segundo capítulo aborda a seletividade das armadilhas utilizadas na captura dos espécimens. No terceiro capitulo foi estimado o tamanho de maturidade sexual morfológica através de dados de comprimento e peso corporal, realizado para S. devillei e S. pictus e no último capítulo foi investigado o tamanho de maturidade a partir de análises histológicas das gônadas de S. pictus. Ao final, foram apresentadas as conclusões gerais e perspectivas.
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Os estádios de desenvolvimento das gônadas de machos e fêmeas de caranguejos Sylviocarcinus pictus (H. Milne Eduards, 1853) foram descritos por meio de observações macroscópicas e microscópicas (técnica histológica). A descrição histológica foi baseada em 40 espécimes (20 de cada sexo). Foram identificados quatro estádios de desenvolvimento para as fêmeas: imaturo, em maturação, maturo e em reabsorção. As seguintes células foram encontradas: ovogônias, ovócitos em vitelogênese inicial, ovócitos em vitelogênese avançada, células foliculares e folículos pós-ovulatórios. Três estádios de desenvolvimento foram encontrados para os machos: imaturo, em maturação e maturo, com indicação de: espermatogônias, espermatócitos, espermátides, espermatozóides e espermatóforos. Tais dados sugerem o padrão descrito na literatura. O tamanho da maturidade sexual foi de 32,3 mm de largura da carapaça para machos e 31,5 mm para fêmeas. Os estádios gonadais observados macroscopicamente por meio do volume e da coloração das gônadas foram validados pela análise histológica, sendo um critério útil e ágil para a identificação da maturidade sexual para a espécie. O presente estudo oferece informações inéditas sobre a biologia reprodutiva de Sylviocarcinus pictus.
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The Spec genes serve as molecular markers for examining the ontogeny of the aboral ectoderm lineage of sea urchin embryos. These genes are activated at late-cleavage stage only in cells contributing to the aboral ectoderm of Strongylocentrotus purpuratus and encode 14,000-17,000 Da calcium-binding proteins. A comparative analysis was undertaken to better understand the mechanisms underlying the activation and function of the Spec genes by investigating Spec homologues from Lytechinus pictus, a distantly related sea urchin. Spec antibodies cross-reacted with 34,000 Da proteins in L. pictus embryos that displayed a similar ontogenetic pattern to that of Spec proteins. One cDNA clone, LpS1, was isolated by hybridization to a synthetic oligonucleotide corresponding to a calcium-binding domain or EF-hand. The LpS1 mRNA has developmental properties similar to those of the Spec mRNAs. LpS1 encodes a 34,000 Da protein containing eight EF-hand domains, which share structural homology with the Spec EF-hands; however, little else in the protein sequence is conserved, implying that calcium-binding is important for Spec protein function. Genomic DNA blot analysis showed two LpS1 genes, LpS1$\alpha$ and LpS1$\beta$, in L. pictus. Partial gene structures for both LpS1$\alpha$ and $\beta$ were constructed based on genomic clones isolated from an L. pictus genomic library. These revealed internal duplications of the LpS1 genes that accounted for the eight EF-hand domains in the LpS1 proteins. Sequencing analysis showed there was little in common among the 5$\sp\prime$-flanking regions of the LpS1 and Spec genes except for the presence of a binding site for the transcription factor USF.^ A sea urchin gene-transfer expression system showed that 762 base pairs (bp) of 5$\sp\prime$-flanking DNA from the LpS1$\beta$ gene were sufficient for correct temporal and spatial expression of reporter genes in sea urchin embryos. Deletions at the 5$\sp\prime$ end to 511, 368, or 108bp resulted in a 3-4 fold decrease in chloramphenicol acetyltransferase (CAT) activity and disrupted the restricted activation of the lac Z gene in aboral ectoderm cells.^ A full-length Spec1 protein and a truncated LpS1 protein were induced and partially purified from an in vitro expression system. (Abstract shortened with permission of author.) ^
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The purpose of this study was to investigate a selection of children's historical nonfiction literature for evidence of coherence. Although research has been conducted on coherence of textbook material and its influences on comprehension there has been limited study on coherence in children's nonfiction literature. Generally, textual coherence has been seen as critical in the comprehensibility of content area textbooks because it concerns the unity of connections among ideas and information. Disciplinary coherence concerns the extent to which authors of historical text show readers how historians think and write. Since young readers are apprentices in learning historical content and conventions of historical thinking, evidence of disciplinary coherence is significant in nonfiction literature for young readers. The sample of the study contained 32 books published between 1989 and 2000 ranging in length from less than 90 pages to more than 150 pages. Content analysis was the quantitative research technique used to measure 84 variables of textual and disciplinary coherence in three passages of each book, as proportions of the total number of words for each book. Reliability analyses and an examination of 750 correlations showed the extent to which variables were related in the books. Three important findings emerged from the study that should be considered in the selection and use of children's historical nonfiction literature in classrooms. First, characteristics of coherence are significantly related together in high quality nonfiction literature. Second, shorter books have a higher proportion of textual coherence than longer books as measured in three passages. Third, presence of the author is related to characteristics of coherence throughout the books. The findings show that nonfiction literature offers students content that researchers have found textbooks lack. Both younger and older students have the opportunity to learn the conventions of historical thinking as they learn content through nonfiction literature. Further, the children's literature, represented in the Orbis Pictus list, shows students that authors select, interpret, and question information, and give other interpretations. The implications of the study for teaching history, teacher preparation in content and literacy, school practices, children's librarians, and publishers of children's nonfiction are discussed.