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61.
Honeybee queen attendants disperse queen pheromones to supplement pheromone dispersal by direct queen-worker contacts. With time they lose their dispersal function exponentially due mainly to volatilization of queen pheromones carried on their bodies. The elimination of those airborne pheromones together with the air while ventilating the hive is balanced by pheromone release by the queen. This equilibrium results in a certain level of queen pheromones in the broodnest. The change of the pheromone level (for example, due to loss of the colony of its queen) can serve as a signal to alter the behaviour of the workers and the state of the colony. 相似文献
62.
63.
Summary The behaviour of DNA from several strains ofB. subtilis andB. brevis on the dropping mercury electrode in a medium of ammonium formate was studied. Native DNA yields in this medium on the oscillogram dE/dt againstE an anodic indentation for which the residues of deoxyguanylic acid are responsible.B. subtilis DNA produces a substantially smaller indentation thanB. brevis DNA does. It was found that the difference is not conditioned by impurities in the DNA samples, nor by the presence of denatured DNA. The difference in the depth of the indentation produced byB. subtilis andB. brevis DNAs almost disappears after denaturation of these DNAs or in an ammonium formate medium of higher concentration. The assumption was advanced that the different oscillopolarographic behaviour of DNAs obtained fromB. subtilis andB. brevis is connected with the different primary structure of these DNAs. 相似文献
64.
The effect of caffeine on nitrosoguanidine-induced mutagenesis ofSalmonella typhimurium & nd its P22 and L phages was studied. The detected mutations included phage “clear” mutations, reversions of phage “amber”
mutation, and prototrophic reversions of thehis
−
auxotroph ofSalmonella typhimurium. Neither therecA mutation of the host nor theerf mutation of the phage genome were found to affect the nitrosoguanidine-induced mutagenesis of the phage during vegetative
growth. Beginning with a concentration of 0.2 mg/ml, caffeine decreased the frequency of mutants by 30–60%, attaining a maximum
effect at 1.5 mg/ml and retaining this effect even at higher concentrations. A similar antimutagenic effeot was observed with
the mutagenesis of the host cells. The nitrosoguanidine-induced mutagenesis does not seem to be related to the function of
therecA cell gene or theerf phage gene. The mechanism of mutagenesis by nitrosoguanidine probably has two components, one of them caffeine sensitive,
the other caffeine-resistant. 相似文献
65.
Studies in the sphingolipids series. XXXV. Separation and chemical characterization of the cerebrins from the yeast Saccharomyces cerevisiae 总被引:2,自引:0,他引:2
Three cerebrins (A, B and C) have been separated from the cerebrin mixture of Saccharomyces cerevisiae by chromatography on Florisil. Cerebrin A contains predominantly n-hexacosanoic acid, cerebrin B 2-hydroxyhexacosanoic acid and cerebrin C 2,3-dihydroxyhexacosanoic acid. 相似文献
66.
Thymineless death (TLD) as well as deoxyribosideless death (DRLD) can be observed inLactobacillus acidophilus R-26 during growth in media lacking thymine or deoxyriboside respectively. Both phenomena exhibit the same interval of lage
period (2–3 h) but the rate of inactivation is 2–3 times faster in TLD. Transfer experiments show that inactivation of bacterial
reproduction is accelerated immediately if—DR medium is replaced by—T one. In the opposite case the deceleration of the inactivation
rate does not appear immediately but after a 1–2 h lag period, in which no changes in the number of viable bacteria can be
observed. Our results suggested that the accumulation of deoxyriboside compounds has no causal role in the inactivation of
bacterial reproduction. However, the presence of deoxyribosides can accelerate the process of inactivation. 相似文献
67.
68.
Systematic Parasitology - The proteocephalid genus Pseudoendorchis (Cestoda: Onchoproteocephalidea) has recently been proposed to accommodate seven species/species-level lineages of tapeworm... 相似文献
69.
Nešić Andrijana Čavić Milena Popović Milica Gavrović-Jankulović Marija 《Molecular biology reports》2021,48(5):4065-4072
Molecular Biology Reports - Actinidin (Act d 1), a highly abundant cysteine protease from kiwifruit, is one of the major contributors to the development of kiwifruit allergy. Many studies have... 相似文献
70.
Andrea Šimková Michal Janáč Pavel Hyršl Vadym Krasnovyd Lukáš Vetešník 《Journal of fish biology》2021,98(4):1155-1171
Hybrid advantage, described as the superiority of hybrids in some traits over their parents and termed the “heterosis effect,” is widely documented in the case of reciprocal crosses of parental species (i.e., hybrids representing the F1 generation). In fish, high survival, fast growth and better health status have been widely documented in F1 hybrids. Nonetheless, the effects of interspecific hybridization on vigour, physiology and immunity-related traits in fish are largely unknown, especially concerning native systems of coexisting parental and hybrid genomes in the same habitat. The present study examined the potential physiological and immune aspects of hybrid heterosis by comparing condition status (measured especially by indexes), haematological profile, glucose concentration and selected parameters of non-specific and specific immunity between the evolutionarily divergent non-congeneric cyprinoid species Abramis brama and Rutilus rutilus and their hybrids representing the F1 generation, all of them caught in nature. Clear differences were documented for vigour-related, physiological and immune parameters between the two divergent species. Hybrids generally tended to express intermediate characters of the measured traits, likely generated by the evolutionary divergence of the hybridizing species; nonetheless, for some traits, hybrids exhibited a character that was more similar to one parental species than to the other. This was interpreted as the heterozygote advantage for F1 hybrids. It is suggested that a maternally inherited genetic background may potentially influence the expression of some branches of non-specific immunity or other aspects related to the fish health status. 相似文献