Further studies on the regulation of the Harderian glands of golden hamsters by the thyroid gland

Summary Long-term increased or decreased circulating levels of thyroid hormones significantly modify porphyrin concentrations and morphology in the Harderian glands of male and female hamsters. Administration of T₃ reduced porphyrin concentrations in females; this treatment or decreasing thyroid hormone levels with KClO₄ suppressed the post-castration rise of porphyrins in males. Hypophysectomy led to increased porphyrins in the Harderian glands of males; this rise was suppressed in hypophysectomized males by T₃ or T₄. In females, hypophysectomy reduced porphyrins which were further reduced by daily administration of T₃ or T₄. These modifications in the normal females were identical in castrated males. Mitotic activity in the Harderian glands of females was stimulated by KClO₄ and by hypophysectomy with or without exogenous T₃. In males, castration increased mitotic activity which was suppressed by T₃ and exacerbated by KClO₄. Increased mitotic activity seemingly follows loss of tissue mass. The data show that thyroid hormones act directly on the Harderian glands rather than indirectly through modification of TSH synthesis/release. Female type glands in males are a consequence of loss of gonadal androgens by castration, or by suppression or loss of thyroid hormones by hypophysectomy or by treatment with KClO₄. However, male type glands in females are the result of androgen treatment, and/or increased levels of thyroid hormones via reduced ambient temperatures or of photic input. We conclude that regulation of the Harderian gland appears to be different in the two sexes.Abbreviations T ₃ Triiodothyronine - T ₄ Thyroxine - TSH Thyroid Stimulating Hormone - KClO ₄ Potassium Perchlorate - h hours - ml milliliter - mg milligram - g gram - male - female - castrated male - AP hypophysectomized - CON Control - ALA delta aminole-vulenic acid - HG Harderian Gland     

西双版纳热带季节雨林植物种类多样性的一种研究方法

一、方法1.样地的选择样地分别选取热带干性季节雨林的典型代表——以箭毒木(Antiaris toxicaria)、龙果(Pouteria grandifolia)为标志的群落,以千果榄仁(Terminalia myriocarpa)、番龙眼     

红池坝地区草地红三叶草的空间分布型

植物种群的空间分布型是生物在特定的条件下形成的,它反映了植物种群个体的散布状态以及对环境的适应性和生境对植物影响的生态反映的生态学关系,是一条可以了解凭种类组成研究演替的研究途径 森下正明(Morisita,1959)提出了扩散指数Io(Morisita's index);美国的Lloyd,(1967)提出了平均拥挤度(Mean crowding,m)这个颇有兴趣     

Zooplankton of Lake Peipsi-Pihkva in 1909–1987

164 taxa were identified in the net zooplankton of the pelagial of L. Peipsi-Pihkva in 1909–1987, including 3 species of protozoans, 74 species of rotifers, 58 species of cladocerans, 28 species of copepods and 1 mollusc. One rotifer species, Ploesoma peipsiense Mäemets et Kutikova, has been described as new for science here. The zooplankton of L. Peipsi-Pihkva is remarkably rich in species including rarities in Estonia: Limnosida frontosa, Drepanothrix dentata, Bythotrephes longimanus, B. cederstroemi etc. Due to its large surface area, L. Peipsi-Pihkva provides a large scale of biotopes of a diverse trophic state and humic content, which support species with different ecological requirements. Most of the aquatory of the lake has lately been mesotrophic, favouring the coexistence of indicators of oligo- and mesotrophic state and species preferring a higher trophic state. The occurrece of 10 species of the genus Bosmina including B. berolinensis, B. gibbera, B. lilljeborgi, B. thersites and B. crassicornis, sparse in Estonian lakes, is the most noteworthy feature of the zooplankton of L. Peipsi-Pihkva. The coexistence of B. coregoni and B. berolinensis, B. gibbera, B. lilljeborgi etc. which were earlier regarded as subspecies of B. c. coregoni proves that they are different species producing usually no hybrids. The species composition was subjected to certain changes during the years under consideration. Larvae of Dreissena were first found in zooplankton in 1962. The oligo-mesotrophic indicator Holopedium gibberum occurred in the lake in 1909–1964, but was lacking in later samples.     

On the biology of bream, Abramis brama (L.) in Lake Peipsi in 1994

The population of bream in L. Peipsi was studied with respect to age, growth rate, condition factor (according to Fulton) and length-weight relationship in 1994. That autumn the bream population in L. Peipsi consisted of fishes aged from 0+ to 15+. During the first year bream reached an average body length of 7.9 cm (the commercial legal size (30 cm) was usually attained by the end of the 5th–6th year. The condition of bream in this lake was above the average of Estonian lakes. The relatively good growth rate and condition of bream in the lake indicates that the waterbody is appropriate for this fish.     

Chromosome analysis and DNA homology in threePicea species,P. mariana,P. rubens,andP. glauca (Pinaceae)

A detailed karyotype analysis was made on the somatic complement ofPicea rubens andP. glauca. B-chromosomes were observed in someP. glauca populations. The karyotypes are generally asymmetrical with most of the chromosomes having median to median-submedian centromeres.Picea glauca chromosomes 2, 3, 7, and 8 have secondary constriction on their short arm and chromosome 10 has a secondary constriction on the long arm. Chromosome 3 was the most easily identifiable, as it has two secondary constrictions located on the short arm. InP. rubens, all the chromosomes but chromosomes 8 and 9 have one to four distinctive secondary constrictions. In general, the diagrammatic comparisons show a high degree of similarity amongP. mariana, P. rubens, andP. glauca. GenomicP. mariana probe strongly hybridized to dots of genomic DNA fromP. rubens andP. glauca indicating that there is a high sequence homology among these three species. The synchronizing agent, hydroxyurea was used at different concentrations to enhance the mitotic index of cell suspensions derived from embryogenic cultures. Hydroxyurea at 1.25 mM increased significantly the mitotic index. An increase of hydroxyurea from 1.25 mM to 5 mM and 10 mM resulted in a steady decrease of mitotic index.     

Maternal mortality and women's condition: “The distress in being a woman”

For millenaria, maternal mortality has been considered as a fatality inherent to women's condition. Thanks to the progress of the obstetric technology, the world M.M.R. fell from 2.000 to 400 per 100.000 births during the past 150 years. At the same time women's condition improved chiefly because of a better level of education. Is there any relationship between them: the decrease of Maternal Mortality and the amelioration of women's general status? Or, in other words, can the decrease of Maternal Mortality Rate be considered as an “indicator” of the situation of women? After a historical review of the importance of the maternal mortality drama as it occured in older times before the “obstetric era”, which began with the improvement of the obstetric technology, this paper will present the actual situation of maternal mortality in relation with the obstetric coverage, the female literacy level and some other socio-economic variables, and in relation with the Gross National Product (G.N.P.) as an indicator of governmental interest in the specific female problems of giving-life.     

黄土高原地区提取植被信息方法的研究

研究评价了适于黄土高原地区植被信息提取的最佳植被指数和方法。该地区分布有落叶阔叶林、草原和荒漠,植被类型丰富多样。然而土壤背景对植被信息提取有较大影响。经对比分析,修正后的土壤调节植被指数（ＭＳＡＶＩ）, 不仅能增强植被信号,并能大大减小土壤背景的影响,同时又能宏观地反映该地区植被类型的分布状况。它是黄土高原地区目前提取植被信息较好的植被指数。标准化差值植被指数（ＮＤＶＩ）、土壤调节植被指数（ＳＡＶＩ）和垂直植被指数（ＰＶＩ）分别适用于高密度、中等密度和稀少植被地区植被信息的提取和监测。各种植被指数多时象累加产生的图像能较好地提取植被信息     

Evaluation of three herbaceous index plant species for bioavailability of soil cadmium, chromium, nickel and vanadium

Uncultivated plants growing on disturbed sites may be useful for assessing the bioavailability of some metals in soils, and thus the potential for metal mobilization up the terrestrial food chain, an important element in ecological risk assessment. A planted chicory cultivar (Cichorium intybus L. var. foliosum Hegi.) and the uncultivated plants horseweed (Canada fleabane) (Erigeron canadensis L.) and dogfennel (Eupatorium capillifolium (Lam.) Small) were evaluated for their ability to act as index plant species for soil Cd, Cr, Ni, and V at two field sites where these metals had been applied five yr previously to two highly weathered sandy Ultisols. Soil Cd was available to all analyzed plant tissues of all three plant species at both sites, particularly on the sandier Blanton soil. Chicory was an effective index plant for Cd on the finer textured Orangeburg soil but functioned as an indicator plant (toxicity symptoms were observed) on the sandier Blanton soil. Horseweed and dogfennel were effective index plants for Cd in both contaminated soils. Soil Cr, Ni, and V were less bioavailable than soil Cd and plant metal uptake was more sensitive to residual soil Cr, Ni, and V than was soil extraction with double acid. Horseweed and chicory may have potential as index plants for soil Cr. Chicory may have potential as a Ni index plant. Chicory and dogfennel may have potential as V index plants.     

High-frequency embryogenesis inBrassica campestris microspore culture

Microspore culture is a very important and useful tool in plant breeding for haploid production and has been developed for many years.Brassica campestris (Brassica rapa L. ssp.oleifera) is an important oilseed crop, but it is relatively recalcitrant in tissue culture including microspore culture. The microspore culture in our laboratory is based on the Canadian protocol. Thirty genotypes ofB. campestris were included in this study; twenty produced embryos. The highest yield was 5930 embryos per 100 buds from Canadian genotype Cv-2, this result was one of the best that had been reported in microspore culture inB. campestris. The buds measuring 2.0 mm to 3.9 mm in length responded best to produce embryos, the optimum timing for microspore culture was confirmed to be during the mid-late to very-late uninucleate stage. The buds could be removed from either the main raceme or lateral racemes. Activated charcoal (150 mg l^-1) was added to the liquid NLN medium, it promoted embryogenesis significantly; embryo development was faster and the embryo yield was significantly higher than those cultures without activated charcoal. The donor plant condition was considered an important factor influencing embryogenesis; older donor plants (older than five weeks) and a cold treatment are recommended.