A physiological dose of estradiol with progesterone affects striatum biogenic amines

The acute effect of estradiol and progesterone on dopamine and serotonin metabolism in rat striatum was studied. One subcutaneous injection of 17 beta-estradiol (300 ng) and progesterone (150 micrograms) into intact male rats increased plasma levels of these steroids, while testosterone, corticosterone, and estrone remained unchanged. Dehydroepiandrosterone, androstane-3 beta, 17 beta-diol and dihydrotestosterone remained undetectably low. Prolactin decreased and androstane-3 alpha, 17 beta-diol, and 17-OH progesterone increased, but less than estradiol and progesterone. Peak levels of striatal dopamine, dihydroxyphenylacetic acid, and homovanillic acid were observed 15-45 min after steroid injection with a return to control values after 45-60 min, while serotonin and 5-hydroxyindoleacetic acid levels were slightly decreased. An injection of estradiol (70 ng) with progesterone (70 micrograms) to ovariectomized female rats left plasma prolactin levels unchanged, while striatum dopamine and serotonin as well as their metabolite concentrations peaked 15-60 min after steroid injection and returned to control values after 45-75 min. To allow for a better comparison of the action of these steroids, the effect of estradiol or progesterone alone and in combination on the brain of ovariectomized rats was compared in the same experiment. A similar increase in metabolites of dopamine levels was observed after these steroids alone or in combination, while dopamine levels were increased only after progesterone alone or in combination with estradiol. An injection of estradiol or progesterone to ovariectomized rats led to peak steroid concentrations at approximately the same time in the brain and plasma. In addition, plasma and brain steroid levels were significantly correlated.(ABSTRACT TRUNCATED AT 250 WORDS)     

Reversibility and "pH-T phase diagrams" of Rapana venosa hemocyanin and its structural subunits

We have studied the stability and reassociation behaviour of native molecules of Rapana venosa hemocyanin and its two subunits, termed RvH1 and RvH2. In the presence of different concentrations of Ca(2+) and Mg(2+) ions and pH values, the subunits differ not only in their reassociation behaviour, but also in their formation of helical tubules and multidecamers. RvH1 revealed a greater stability at higher pH values compared to RvH2. Overall, the stability of reassociated RvH and its structural subunits was found to be pH-dependent. The increasing stability of native Hc and its subunits, shown by pH-induced CD transitions (acid and alkaline denaturation), can be explained with the formation of quaternary structure. The absence of a Cotton effect at temperatures 20-40 degrees C in the pH-transition curves of RvH2 indicates that this subunit is stabilized by additional "factors", e.g.: non-ionic/hydrophobic stabilization and interactions of carbohydrate moieties. A similar behaviour was observed for the T-transition curves in a wide pH interval for RvH and its structural subunits. At higher temperatures, many of the secondary structural elements are preserved especially at neutral pH, even at extreme high temperatures above 90 degrees C the protein structures resemble a "globule state".     

Isolation and characterization of 23 polymorphic microsatellite loci for a West Indian iguana (Cyclura pinguis) from the British Virgin Islands

Twenty-three polymorphic microsatellite markers were identified and characterized for Cyclura pinguis, a critically endangered species of lizard (Sauria: Iguanidae) native to Anegada Island in the British Virgin Islands. We examined variation at these loci for 39 C. pinguis, finding up to five alleles per locus and an average expected heterozygosity of 0.55. Allele frequency estimates for these microsatellite loci will be used to characterize genetic diversity of captive and wild C. pinguis populations and to estimate relatedness among adult iguanas at the San Diego Zoo that form the nucleus of a captive breeding programme for this critically endangered species.     

Oviposition of the Colorado potato beetle (Leptinotarsa decemlineata) and natural predation on its egg masses in Bt-expressing fields

Generalist predators are relevant natural enemies of the Colorado potato beetle (CPB) in Europe. In fields of insect resistant genetically modified plants (GMPs), predators could be exposed to toxins either directly (e.g., via pollen), or indirectly through feeding on herbivorous prey. Hence, they represent an important functional group to consider when studying environmental impacts of GMPs. CPB females show a ‘bet-hedging’ strategy in spatial and temporal distribution of eggs, through which the species tries to minimize the risks of progeny loss due to adverse conditions. Experimental fields of GM eggplants expressing Cry3Bb toxin and potatoes expressing Cry1Ab toxin were set up. CPB egg masses were counted on naturally infested plants at four time points during the field season of each crop. To assess predation, newly deposited egg masses were marked at the same dates. Daily visual observations were conducted recording the numbers of intact or preyed eggs and neonate larvae. In both cases, oviposition was similar between GM and control plots, as the number of egg masses per plant and the number of eggs per mass did not differ significantly between treatments. A statistical analysis of the spatial distribution of egg masses revealed a similar aggregation in the potato field, whereas in the eggplant field, the variance of the number of egg masses per plant was smaller than expected in GMP plots. The predation rate was similar between treatments. These results suggest that the ecological function of natural predation on CPB eggs in GM plots was not impaired.     

Construction of recombinant plasmids containing rat thyroglobulin mRNA sequences

Two plasmids containing rat thyroglobulin cDNA sequences have been constructed and characterized. A plasmid with a 500-bp insert (pRT6) was isolated and identified as thyroglobulin-specific on the basis of the tissue specificity of the inserted sequence and of its ability to retain thyroglobulin mRNA on a nitrocellulose filter. The cDNA insert in pRT6 was subsequently used to screen a rat thyroid cDNA library constructed with large cDNA. A plasmid was found containing a 1700-bp insert. The polarity and the fidelity of the insert is demonstrated by S1 mapping.     

A critical role of protein-bound water in the catalytic cycle of cytochrome P-450 camphor.

The rates of NADH oxidation during the hydroxylation of camphor by cytochrome P-450cam were followed in the presence of co-solvents used to increase the osmotic pressure surrounding the protein-bound water. As a result, the measured Vmax decreases independently of the perturbant tested. Roughly 28 molecules of water, involved during the catalytic cycle, are deduced from the variation of Vmax as a function of osmotic pressure. These molecules, in part, could be those present in the cytochrome P-450cam-putidaredoxin interface.     

Spermiogenesis in the Australian cockatiel Nymphicus hollandicus

Information on the ultrastructure of parrot spermatids and spermatozoa is limited to only four species with no comprehensive study of spermiogenesis conducted within the order Psittaciformes. The present study was undertaken to describe the development of the cockatiel spermatid using electron microscopy. Four phases of spermatid maturation were documented on the basis of nuclear morphology, development of the acrosome, perforatorium, and axial filament. These phases included 1) round nuclei, 2) irregular nuclei, 3) elongated nuclei with granular chromatin, and 4) elongated nuclei with homogenous chromatin. While development of the cockatiel spermatid was comparable to that of other domestic avian species, we have noted the hollow nature of some chromatin granules, an abnormal formation of the axoneme, the absence of the fibrous sheath around the axoneme of the principal piece, and the absence of an annulus. J. Morphol. , 2012. © 2012 Wiley Periodicals, Inc.     

Ubiquitin-interacting motifs inhibit aggregation of polyQ-expanded huntingtin

Expansion of polyglutamine (polyQ) tracts within proteins underlies a number of neurodegenerative diseases, such as Huntington disease, Kennedy disease, and spinocerebellar ataxias. The resulting mutant proteins are unstable, forming insoluble aggregates that are associated with components of the ubiquitin system, including ubiquitin, ubiquitin-like proteins, and proteins that bind to ubiquitin. Given the presence of these ubiquitin-binding proteins in the insoluble aggregates, we examined whether heterologous expression of short motifs that bind ubiquitin, termed ubiquitin-interacting motifs (UIMs), altered the aggregation of polyQ-expanded huntingtin (Htt), the protein product of the Huntington disease gene. We found that a subset of UIMs associated with mutant Htt. The ability to interact with ubiquitin was necessary, but not sufficient, for interaction with mutant Htt. Furthermore, we found that expression of single, isolated UIMs inhibited aggregation of mutant Htt. These data suggest that isolated UIMs might serve as potential inhibitors of polyQ-aggregation in vivo.     

紫背金盘(Ajuga nipponensis)次生物质对桔全爪螨(Panonychus citri)的驱避作用

研究了紫背金盘Ajuga nipponensis Makino各溶剂提取物和部分化合物对桔全爪螨Panonychus citri McGregor雌成螨及其产卵的驱避作用.结果表明,石油醚萃取物、乙酸乙酯萃取物具有较强的生物活性.在0.1 g · L-1时, 石油醚和乙酸乙酯萃取物对该螨处理1d后的产卵忌避率分别为:84.86%、69.88%;2d后为89.49%、82.19%;对雌成螨驱避率分别为:85.08%、68.66%;2d后为50.96%、69.84%.乙酸乙酯萃取物经分离得到四类化合物,结果表明:馏分Ⅰ为长链脂肪酸混合物,具有较强生物活性,2000μg/ml和1000μg/ml处理1d后,产卵忌避率分别为:80.77%、74.77%;2d后为73.81%、72.59%.2000μg/ml处理1d后对雌成螨的驱避率为:69.88%;2d后为74.24%.刺槐素Ⅱ、新克罗烷化合物Ⅲ和β-蜕皮甾酮Ⅳ在2000μg/ml均不表现活性.对馏分Ⅰ中的4个主要化合物单体进行活性测定,结果表明:十六烷酸、十六烷酸甲酯、十六烷酸乙酯和十八烷酸甲酯在2000μg/ml处理时,1d后,产卵驱避率分别为:75.18%、61.76%、59.18%和66.49%;2d后产卵驱避率为:66.67%、31.15%、46.75%和44.84%;雌成螨驱避率分别为:1d后,67.53%、63.79%、59.26%和68.00;2d后,67.23%、43.96%、48.23%和64.19%.在1000μg/ml处理时,1d 后,产卵驱避率分别为:59.21%、59.16%、57.02%和61.40%;1d后,雌成螨驱避率分别为:69.64%、61.43%、55.76%和64.00%.