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Swiss, 60-day castrate mice were injected with 0.5, 1.5 or 5.0 mg of testosterone propionate (TP; single dose, subcutaneously) 5 days before sacrifice, in order to investigate the ability of the submandibular gland (SMG) and other androgen target tissues to recover their normal morphology and function. Some animals were additionally injected intraperitoneally with ZnCl2 (0.14 or 0.28 mg Zn2+/animal per day) during the last 15 days before sacrifice. Only SMG tissue fully recovered by TP treatment. ZnCl2 significantly impaired the dose-dependent recovery of the granular ducts of mouse SMG tissue and that of other organs which display 'androgenic' (prostate, epididymis) and 'anabolic' responses (bulbocavernosus muscle). Histological examination of testes and epididymides of intact mice injected with ZnCl2 revealed abnormal spermatogenesis with multinucleated cells and acidophilic bodies within the tubular lumen; the circulating levels of testosterone in these animals were low. In vitro, Zn2+ inhibited androgen-binding activity in SMG cytosol, but the binding capacity increased in SMG of zinc-injected animals. It is suggested that zinc, although essential for the androgenic expression, is critical as far as its intracellular concentrations are concerned and that pharmacological doses of Zn2+ determine androgenic suppression by competition at receptor and acceptor levels. 相似文献
74.
Seed predation by howler monkeys is poorly documented. Here we report the seed predation onCariniana estrellensis (Lecythidaceae) fruits by the black howler monkeyAlouatta caraya in south-east Brazil during an intense dry season. This observation suggests that even non-specialized seed predators such
as howlers can use seeds in critical periods of dry season. 相似文献
75.
A molecular and evolutionary study of the beta-globin gene family of the Australian marsupial Sminthopsis crassicaudata 总被引:1,自引:0,他引:1
Cooper SJ; Murphy R; Dolman G; Hussey D; Hope RM 《Molecular biology and evolution》1996,13(7):1012-1022
Beta-globin gene families in eutherians (placental mammals) consist of a
set of four or more developmentally regulated genes which are closely
linked and, in general, arranged in the order 5'-embryonic/fetal genes-
adult genes-3'. This cluster of genes is proposed to have arisen by tandem
duplication of ancestral beta-globin genes, with the first duplication
occurring 200 to 155 MYBP just prior to a period in mammalian evolution
when eutherians and marsupials diverged from a common ancestor. In this
paper we trace the evolutionary history of the beta-globin gene family back
to the origins of these mammals by molecular characterization of the
beta-globin gene family of the Australian marsupial Sminthopsis
crassicaudata. Using Southern and restriction analysis of total genomic DNA
and bacteriophage clones of beta-like globin genes, we provide evidence
that just two functional beta-like globin genes exist in this marsupial,
including one embryonic- expressed gene (S.c-epsilon) and one
adult-expressed gene (S.c-beta), linked in the order 5'-epsilon-beta-3'.
The entire DNA sequence of the adult beta-globin gene is reported and shown
to be orthologous to the adult beta-globin genes of the North American
marsupial Didelphis virginiana and eutherian mammals. These results,
together with results from a phylogenetic analysis of mammalian beta-like
globin genes, confirm the hypothesis that a two-gene cluster, containing an
embryonic- and an adult-expressed beta-like globin gene, existed in the
most recent common ancester of marsupials and eutherians. Northern analysis
of total RNA isolated from embryos and neonatals indicates that a switch
from embryonic to adult gene expression occurs at the time of birth,
coinciding with the transfer of the marsupial from a uterus to a pouch
environment.
相似文献
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77.
Mohammad?Abass?AhangerEmail author Megha?Tittal Rayees?Ahmad?Mir RM?Agarwal 《Protoplasma》2017,254(5):1953-1963
Present communication reports laboratory and pot experiments conducted to study the influence of water and osmotic stress on nitrogen uptake and metabolism in two wheat (Triticum aestivum L) cultivars with and without potassium supplementation. Polyethylene glycol 6000-induced osmotic stress/restricted irrigation caused a considerable decline in the activity of nitrate reductase, glutamate synthase, alanine and aspartate aminotransferases, and glutamate dehydrogenase. Potassium considerably improved nitrogen metabolism under normal water supply conditions and also resulted in amelioration of the negative impact of water and osmotic stresses indicating that potassium supplementation can be used as a potential tool for enhancing the nitrogen use efficiency in wheat for exploiting its genetic potential. 相似文献
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With the cancellation of fenamiphos in the near future, alternative nematode management tactics for plant-parasitic nematodes (PPN) on golf courses need to be identified. The use of entomopathogenic nematodes (EPN) has been suggested as one possible alternative. This paper presents the results of 10 experiments evaluating the efficacy of EPN at managing PPN on turfgrasses and improving turf performance. These experiments were conducted at various locations throughout Florida over the course of a decade. In different experiments, different EPN species were tested against different species of PPN. Separate experiments evaluated multiple rates and applications of EPN, compared different EPN species, and compared single EPN species against multiple species of PPN. In a few trials, EPN were associated with reductions in certain plant-parasite species, but in other trials were associated with increases. In most trials, EPN had no effect on plant parasites. Because EPN were so inconsistent in their results, we conclude that EPN are not acceptable alternatives to fenamiphos by most turf managers in Florida at this time. 相似文献
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