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691.
Behavioural evidence for polarization vision in crickets   总被引:2,自引:0,他引:2  
ABSTRACT. Tethered field crickets, Gryllus campestris L., walking on an air-suspended bail exhibit a spontaneous response to the e-vector of polarized light presented from above: E-vector orientation controls strength and direction of turning tendency. Experiments in which different eye regions are covered with paint suggest that this response is mediated by the anatomically and physiologically specialized dorsal rim area of the compound eye. We conclude that crickets have polarization vision and that the dorsal rim area of the eye plays a key role in this sensory capacity.  相似文献   
692.
Daniel, P. P. and Bryant, J. A. 1988. DNA ligase in pea (Pisumsativum L.) seedlings: changes in activity during germinationand effects of deoxyribonucleotides.—J. exp. Bot. 39:481–486. Measurable amounts of ‘soluble’ and chromatin-boundDNA bgase are present in the embryo axis at least as early as8 h after the onset of imbibition. Between 8 h and 48 h theactivity of the chromatin-bound form increases nearly 10-fold,whilst the soluble activity increases 6-fold. There is thena slight decline in the chromatin-bound activity between 48h and 72 h, whilst the soluble activity continues to increase. Both forms of ligase arc markedly inhibited by dTTP (but notby other deoxyribonucleoside triphosphates); the soluble formis significantly more sensitive to dTTP than the chromatin-boundform. Key words: Pisum satioum, DNA ligase, germination  相似文献   
693.
694.
ABSTRACT Because coyotes (Canis latrans) show an aversion to novel objects, we examined the effects of the presence and removal of repellent and attractive stimuli on coyote behavior. We found a greater proportion of captive coyotes investigated 10-cm-tall cones (0.95) compared to 90-cm-tall cones (0.68) and control sites (0.81), and spent longer periods (P < 0.001 in all instances) investigating small cones (x̄ = 465 sec), compared to large cones (x̄ = 212 sec) and control sites (x̄ = 45 sec). However, investigation times at sites following removal of large cones were 1.6 and 2.3 times greater than investigation times at sites following removal of small cones and the control, respectively. Results from pen studies were supported by a field study. Wild coyotes in south Texas visited 43% of small cones but did not visit large cones. Following removal of cones, visits to small cone stations decreased to 29%, whereas coyotes visited 43% of large cone stations. Thus, we observed a direct relationship between aversion toward large novel objects and subsequent attraction to sites following their removal among both captive and wild coyotes. Based upon our results, we suggest that placing large novel objects over traps that are set and removing such objects after a few days, with the subsequent addition of an olfactory attractant, may increase exploratory behavior and capture of coyotes.  相似文献   
695.
Sand flies in the psychodid subfamily Phlebotominae carry important human pathogens in the trypanosomatid protozoan genus Leishmania (Cupolillo). Despite the fact that hundreds of sequences for this group are now publicly available, they constitute different sets of taxa and genetic markers. Integrating these data to construct a molecular phylogeny of the family is a significant bioinformatics challenge. We used sequences of eight markers obtained from freshly collected sand flies from Ethiopia and combined them with over 1300 publicly available sequences, performing a combined analysis after generating single terminal sequences from ancestral reconstructions for some individual markers. The resulting phylogeny had 113 terminals and recovered Phlebotominae and certain species groups as monopheletic. Although the 20 outgroups in Psychodinae were recovered as a well‐resolved clade with bootstrap support for many internal clades, Phlebotominae was recovered as several lineages with unclear relationships among them. However, phlebotomines clustered by geographic region, the most notable being all the New World species except Brumptomyia (Galati), which were recovered as monophyletic. Our phylogeny suggests a Sub‐Saharan African or South Asian origin for the subfamily, which subsequently expanded to the north and west, and eventually to the New World. Supported species groups are often composed of widespread species with overlapping ranges. This result highlights the need for a large increase in the amount and diversity of molecular sequence data, and a broad selection of terminals, to test taxonomic hypotheses and examine speciation processes in this important group of flies.  相似文献   
696.
Abstract:  A new neosuchian crocodylomorph, Susisuchus jaguaribensis sp. nov., is described based on fragmentary but diagnostic material. It was found in fluvial-braided sediments of the Lima Campos Basin, north-eastern Brazil, 115 km from where Susisuchus anatoceps was found, in rocks of the Crato Formation, Araripe Basin. S. jaguaribensis and S. anatoceps share a squamosal–parietal contact in the posterior wall of the supratemporal fenestra. A phylogenetic analysis places the genus Susisuchus as the sister group to Eusuchia, confirming earlier studies. Because of its position, we recovered the family name Susisuchidae, but with a new definition, being node-based group including the last common ancestor of Susisuchus anatoceps and Susisuchus jaguaribensis and all of its descendents. This new species corroborates the idea that the origin of eusuchians was a complex evolutionary event and that the fossil record is still very incomplete.  相似文献   
697.
An effective way for inoculation of bacteria into dry foods/ingredients that gives a uniform mixture was developed. In the first part of this experiment, Salmonella typhimurium was successfully inoculated into chalk. Chalk tubes were weighed then soaked in a broth with S. typhimurium and allowed to dry back to their original weight. the dried chalk was made into a powder form. A viable cell count of this chalk, using a selective media for S. typhimurium , showed that the organism survived the drying while entrapped in the chalk. the "charged" chalk was used in an experiment as a dry inoculum where it was mixed with a low-moisture poultry feed. In comparison to a liquid inoculum, the "charged" chalk was a superior way of inoculating into dry particles because it created a more homogenous mixture with the feed without altering any properties of the feed itself. the second part of this experiment entailed a shelf-life study of the "charged" chalk. the same procedures for inoculating chalk were done using ten different cultures including Bacillus cereus, Clostridium perfringens, Escherichia coli, Enterobacter aerogenes, Lactobacillus plantarum, Listeria monocytogenes, Pseudomonas aeruginosa, Salmonella typhimurium, Staphylococcus aureus , and Streptococcus faecalis. Data showed that the cultures are stable in the chalk for at least six months.  相似文献   
698.
ABSTRACT The wildlife conservation institution (Institution) needs to reform to maintain legitimacy and relevancy in the 21st century. Institutional reform is inherently slow. Limitations resulting from historical and resource dependencies between state wildlife agencies and hunters have left the Institution poorly positioned to meet changing ecological and social complexities. In this paper, we suggest that an ideal Institution would have the following 4 components: broad-based funding, trustee-based governance, multidisciplinary science as the basis of recommendations from professional staff, and involvement of diverse stakeholders and partners. Our suggestions reflect the fundamental tenets of the Public Trust Doctrine, which we believe is the foundation of the Institution. In bringing forth these ideas, we hope to encourage discussion about how the Institution should reform to meet the changing needs of society.  相似文献   
699.
700.
Some asymptotic properties of jackknife statistics   总被引:1,自引:0,他引:1  
THORBUBN  DANIEL 《Biometrika》1976,63(2):305-313
  相似文献   
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