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761.
762.
Lizards (Tiliqua scincoides) regulated their internal body temperature by moving back and forth between 15 degrees and 45 degrees C environments to maintain colonic and brain temperatures between 30 degrees and 37 degrees C. A pair of thermodes were implanted across the preoptic region of the brain stem, and a reentrant tube for a thermocouple was implanted in the brain stem. Heating the brain stem to 41 degrees C activated the exit response from the hot environment at a colonic temperature 1 degrees to 2 degrees C lower than normal, whereas cooling the brain stem to 25 degrees C delayed the exit from the hot environment until the colonic temperature was 1 degrees to 2 degrees C higher than normal. The behavioral thermoregulatory responses of this ectotherm appear to be activated by a combination of hypothalamic and other body temperatures.  相似文献   
763.
Regulation of the germinal center response by microRNA-155   总被引:1,自引:0,他引:1  
MicroRNAs are small RNA species involved in biological control at multiple levels. Using genetic deletion and transgenic approaches, we show that the evolutionarily conserved microRNA-155 (miR-155) has an important role in the mammalian immune system, specifically in regulating T helper cell differentiation and the germinal center reaction to produce an optimal T cell-dependent antibody response. miR-155 exerts this control, at least in part, by regulating cytokine production. These results also suggest that individual microRNAs can exert critical control over mammalian differentiation processes in vivo.  相似文献   
764.
765.
Polar transport-dependent local accumulation of auxin provides positional cues for multiple plant patterning processes. This directional auxin flow depends on the polar subcellular localization of the PIN auxin efflux regulators. Overexpression of the PINOID protein kinase induces a basal-to-apical shift in PIN localization, resulting in the loss of auxin gradients and strong defects in embryo and seedling roots. Conversely, pid loss of function induces an apical-to-basal shift in PIN1 polar targeting at the inflorescence apex, accompanied by defective organogenesis. Our results show that a PINOID-dependent binary switch controls PIN polarity and mediates changes in auxin flow to create local gradients for patterning processes.  相似文献   
766.
Arctic sculpins of the genus Myoxocephalus adapted to water at 5 degrees C escaped from warm water at 20 degrees , 16 degrees , and 12 degrees C when their deep-body temperatures increased from an initial 5 degrees C to about 8 degrees C. Heating parts of the forebrain with water at 25 degrees C circulating through a pair of thermodes astraddle rostral parts of the forebrain shortened the time spent in the warm water and lessened the incease in deep-body temperature before exit from the warm water. Cooling the forebrain to about -1 degrees C caused a large increase in the body temperature and sometimes suppressed the escape from the warm water.  相似文献   
767.
Zusammenfassung Mit der Faktorenanalyse nach der Hauptachsenmethode und der aufbauenden multiplen Regressionsanalyse konnte gezeigt werden, daß die Rohverfärbung der Kartoffelknolle im wesentlichen von der Aktivität der Polyphenoloxydase, sowie den Gehalten an Gesamtphenol, basischen Aminosäuren, Trockensubstanz, Chlorogensäure, Flavonolen usw. abhängt. Der errechnete Einfluß der basischen Aminosäuren auf die Verfärbungsneigung der Knolle kann zum gegenwärtigen Zeitpunkt noch nicht erklärt werden.
Relationships between enzymic browning of potatoes and several constituents of the tuber.With a factorial analysis and a multiple regression analysis could be shown that the enzymic browning of the potato tuber is essentially influenced by the polyphenol oxidase activity, content of total phenolics, basic amino acids, dry matter content, chlorogenic acid, and flavonols.The influence of basic amino acids on enzymic browning can not be explained at present.Further investigations are necessary.

Resume Relations entre le brunissement enzymatique des pommes de terre, et divers constituants du tubercule.L'analyse factorielle, l'analyse de la régression multiple, démontrent que le brunissement enzymatique du tubercule de pomme de terre est influencé essentiellement par l'activité des polyphénols oxydases, par le taux de polyphénols totaux, par les aminoacides basiques, par le taux de matière sèche, par l'acide chlorogénique et par les flavonols.L'action des aminoacides basiques sur le brunissement enzymatique n'a pas pu être expliqué jusqu'à present.De nouvelles recherches sont nécessaires.
  相似文献   
768.
The objective was to investigate the spread of S. aureus in seven dairy herds. Milk samples were taken to determine mastitis pathogens and somatic cell count. An approved hygiene programme was established to control the spread of S. aureus from quarter to quarter. S. aureus isolates were differentiated by geno- and phenotyping to trace their spread within a herd.In two herds S. aureus showed a high prevalence, but were eliminated from the herds by the control programme. In these herds and a third herd typing results identified a particular type that was found much more frequently than all other types. The frequent types were repeatedly detectable during the study. In three other herds with a lower S. aureus prevalence and also in one herd with a long history of S. aureus and high prevalence subclinical mastitis was caused by several distinguishable S. aureus types. These types occurred simultaneously in the particular herd and showed little or no tendency to spread from quarter to quarter. They seemed to circumvent the control procedures resulting in a relatively high rate of new infected animals and therefore were hardly eliminated. The typing results and the clinical observations indicated that strains differed in their tendency to spread and their ability to infect udder quarters. In three herds typing methods identified a predominant type with the common epidemiological features of a contagious mastitis pathogen, while in the other herds the S. aureus type patterns were similar to that of environmental pathogens.  相似文献   
769.
Impaired abomasal motility and an increased accumulation of gas are prerequisites for displacement of the abomasum in the cow. Predisposing factors are the breed (e.g. Holstein-Friesian, Simmental-Red-Holstein cross breeds and Guernsey), genetic background, twin pregnancy, first weeks of lactation, metabolic disorders (ketosis, increased lipomobilisation, insulin resistance), high-concentrate and low-fibre diets, as well as other concomitant diseases, such as endometritis, mastitis and claw disorders. There does not appear to be a strong correlation between increased milk yield or endotoxaemia and abomasal displacement. Recent studies have focused on possible functional disorders of the enteric nervous system within the abomasal wall, since cattle with abomasal displacement have an increased activity of neuronal nitric oxide synthase, as well as decreased acetylcholine sensitivity. In addition, there appear to be significant differences between breeds in the levels of the neurotransmitters substance P (SP) and vasoactive intestinal peptide (VIP) in the abomasal wall. For example, SP (stimulatory) was significantly less in German Holsteins in comparison to the German Fleckvieh, whereas VIP (inhibitory) was markedly increased. These risk factors may explain why Holstein cows are more susceptible to abomasal displacement than other breeds.  相似文献   
770.
The objective of the study is to map citizen attitudes towards pig meat production systems, and to investigate whether these attitudes associate with pork and pork product consumption. A conjoint experiment was carried out with empirical data collected from 1931 individuals in four European countries with higher-than-average per capita meat consumption (Belgium, Denmark, Poland and Germany). The experiment was based on the following pig farming characteristics: herd size, housing and floor type, efforts to reduce the impact of the production system on the environment, animal feed designed for producing pork with specific fat content, and finally the preferred quality characteristics of the pork end-product. The results of the conjoint analysis were used for a subsequent cluster analysis in order to identify European citizen clusters. Respondents' socio-demographic profile, attitudes towards issues that are expected to influence the way people evaluate pig meat production systems, and consumption frequency of various pork products are used as background information to identify segment profiles. Pork appears to play a substantial role as a part of the diet for most respondents in the four countries of this study. The results of the conjoint experiment at the sample level show that people assigned most importance to animal and environmental well-being as criteria to discriminate between “good” and “bad” pig production practices, despite the fact that their attitudes towards environmental protection, animal welfare and industrial food production were only moderately strong. Moreover, the results of the cluster analysis allowed small-sized, clear-cut clusters of citizens to appear, which pay attention to specific pig farming attributes. In conclusion, attitudes towards environment and nature, animal welfare and the need for an environment-friendly food production were indeed related to citizens' specific attitudes towards pig farming at the cluster level. However, the relationship between citizenship and consumption behaviour was found to be weak. What people think in their role as citizens related to pig production did not appear to significantly influence their pork consumption choices.  相似文献   
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