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61.
This paper offers the suggestion that heat shock inhibition of tubulin synthesis accounts for the molecular mechanism by which periodic heat shocks induce cell synchrony in Tetrahymena. Each heat shock (34 °C) represses tubulin synthesis and blocks the division cycle at the point when the oral structure, rich in microtubules, would normally begin to assemble. Recovery (at 28 °C) from each heat shock is characterized by parallel derepression of tubulin synthesis and of oral development. Changes in protein synthesis patterns are complex when the temperature is shifted up and down between 28 and 34 °C and further experimental support is required in support of the hypothesis here forwarded. 相似文献
62.
Lysine vasopressin (LVP), arginine vasopressin, oxytocin, and arginine vasotocin administered intraventricularly (icv) to mice all provoked a dose-dependent behavioral response in the range 0.1 – 1.0 μg. This response included a pronounced hyperactivity, extensive foraging, increased grooming, and at higher doses, stereotyped scratching, squeaking, and occasional barrel rolling. The four hormones were all approximately equipotent. Desglycinamide lysine vasopressin and [desaminocys1, D-Arg8] vasopressin produced some of the characteristic behaviors, but were much less potent. While pretreatment of the animals with reserpine (5 mg/kg ip), haloperidol (0.5 mg/kg ip), or physostigmine (0.5 mg/kg ip) sedated the animals and attenuated the locomotion and grooming, these drugs did not substantially alter the characteristic behavioral responses to LVP. Pretreatment with α-methyl-p-tyrosine (400 mg/kg ip), p-chlorophenylalanine (320 mg/kg ip), 6-hydroxydopamine (100 μg icv), ergotamine (0.5 μg icv), ethoxolamide (52 ng icv), diphenhydramine (20 μg icv), prostaglondin F2α (2 μg icv), or naloxone (1 mg/kg ip) did not alter the LVP-induced behaviors. None of these drugs or
-amphetamine (0.5 to 20 mg/kg ip) or nicotine (0.1 or 1 μg icv) mimicked the behavioral effects of the hormones. 相似文献
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64.
Tamar Ron 《Ethology : formerly Zeitschrift fur Tierpsychologie》1996,102(1):128-133
The study troop of chacma baboons (Papio cynocephalus ursinus) at Mkuzi Game Reserve, Zululand, South-Africa, comprised of about 76 members that split into two new troops. The events leading to this troop fission will be described and its possible causes will be discussed. Troop fission among baboons is generally attributed to the withdrawal of low-ranking females from the main group, as a result of the cost of food competition and its effect on their reproductive success. At Mkuzi, no evidence for food competition among females was recorded in terms of rank-related time spent feeding or other time—budget components, feeding-bout length, diet composition or context of female aggression. Moreover, no evidence for rank-related differential reproductive success was found in terms of inter-birth intervals or infant survival. Female mortality was, however, related to dominance rank, with circumstantial evidence suggesting that cause of mortality was predation by leopards. Rate of female disappearances, aggression levels among females, and the percentage of time they spent in proximity to other adult troop members increased after fission. Relatively short inter-birth intervals and extremely low infant mortality rate at Mkuzi resulted in a small number of receptive females at any one time, and therefore in high costs of male sexual competition as expressed in the high levels of male aggression and woundings, both reduced after fission. It is suggested that this troop fission may have been initiated by the resident males, triggered by the high cost of sexual competition, and forced on the females, who were, consequently, subjected to higher risk of predation. The troop fission was preceded by a long process of increasing tendency for sub-trooping. It was initiated by the four resident males who kept a large distance apart from each other, herded oestrous female associates away from others and were followed by other females. The females generally tended to stay close to associates, males and females. These parties were followed by the peripheral and immigrant males who had no female associates, and eventually two distinct daughter troops were formed. 相似文献
65.
G.C. Krijger H.A. Claessens H. Th. Wolterbeek 《Chemical Speciation and Bioavailability》2013,25(1-2):29-36
ABSTRACTThe present paper addresses the potential use of capillary zone electrophoresis (CZE) as an analytical tool in 99- technetium speciation studies. In order to optimise sampling, storage and analytical procedures, the three marker compounds 99mTcO4-, 99mTc-DTPA and 99mTc-citrate were synthesised and used in test-measurements with CZE. The results underline the superior separation power of the CZE technique, and indicate good CZE performance for the stable 99mTcO4- and 99mTc-DTPA compounds. The data suggest that CZE may be used without problems for various Tc-compounds of intermediate mobilities. The specific data of 99mTc-citrate suggest that with this marker compound a threshold lability is reached for the use of CZE in plant Tc-speciation studies. This result means that CZE cannot be used in analyses of Tc-compounds which are less stable than Tc-citrate. Future CZE work will comprise the synthesis and use of Tc-markers of intermediate mobilities and stabilities; furthermore, effects of marker matrices and the plant matrix on CZE performance will be investigated. 相似文献
66.
Genome-wide expression profiling has revolutionized biomedical research; vast amounts of expression data from numerous studies of many diseases are now available. Making the best use of this resource in order to better understand disease processes and treatment remains an open challenge. In particular, disease biomarkers detected in case–control studies suffer from low reliability and are only weakly reproducible. Here, we present a systematic integrative analysis methodology to overcome these shortcomings. We assembled and manually curated more than 14 000 expression profiles spanning 48 diseases and 18 expression platforms. We show that when studying a particular disease, judicious utilization of profiles from other diseases and information on disease hierarchy improves classification quality, avoids overoptimistic evaluation of that quality, and enhances disease-specific biomarker discovery. This approach yielded specific biomarkers for 24 of the analyzed diseases. We demonstrate how to combine these biomarkers with large-scale interaction, mutation and drug target data, forming a highly valuable disease summary that suggests novel directions in disease understanding and drug repurposing. Our analysis also estimates the number of samples required to reach a desired level of biomarker stability. This methodology can greatly improve the exploitation of the mountain of expression profiles for better disease analysis. 相似文献
67.
Lyn L. Dean Ron B. Podesta 《Biochimica et Biophysica Acta (BBA)/General Subjects》1984,799(2):106-114
Polypeptide fractions labelled with [14C]leucine and associated with fractioned inner plasma membrane and outer bilayer (envelope) from the apical double bilayer complex of the surface epithelium of the human blood fluke, Schistosoma mansoni, were analyzed by two-dimensional electrophoresis and fluorography. In contrast to the distribution of alkaline phosphatase, the polypeptide profiles of the two bilayer fractions were similar due to cross contamination between one membrane containing larger amounts of protein (inner) and the second bilayer having more heavily labelled proteins (outer bilayer). Convincing evidence for only two of 35 polypeptides could be provided for localization to the outer bilayer. These results suggest that the marker enzyme used for the inner bilayer, alkaline phosphatase, may not be homogeneously distributed in this membrane. In pulse-chase studies a correction factor for cross-contamination was derived. The rate to turnover of the polypeptide fractions was twice as fast for the outer compared to the inner membrane, this difference being consistent with the view that multilamellar bodies are the precursors of the apical double bilayer complex. Comparing the rates of surface renewal in adult and juvenile schistosomes leads to the suggestion that membrane turnover can be correlated with susceptibility to host immune effector mechanisms. 相似文献
68.
Ron Aiken 《Hydrobiologia》1981,76(1-2):11-12
Female Palmacorixa nana showed clear preference for wood oviposition substrates over Elodea and plexiglass in both laboratory and field experiments. Wood was chosen because of its rigidity and rough surface. These data raise the possibility that males could gain access to females by controlling localized resources.Present address: Department 0f Entomology University 0f Alberta Edmonton, Alberta, Canada T6 G 2E3Present address: Department 0f Entomology University 0f Alberta Edmonton, Alberta, Canada T6 G 2E3 相似文献
69.
70.
Jin Hao Kim Hak Sung Yu Seung Taek Shin Sae Ron Lee Sung Hee Seo Geom Seog 《Molecular biology reports》2021,48(2):1171-1180
Molecular Biology Reports - A large body of research has demonstrated a synergistic anticancer effect between docosahexaenoic acid (DHA) and standard chemotherapy regimens against colorectal cancer... 相似文献