保护生物学概要

保护生物学的形成是对生物危机的反应和生物科学迅速发展的结果。它是应用科学解决由于人类活动干扰或其它因素引起的物种、群落和生态系统出现的问题的新学科。其”目的是提供保护生物多样性的原理和工具“,其基础科学和应用科学的综合性交叉学科。系统学、生态学、生物地理学和种群生态学的原理和方法是保护生物学重要的理论和实践基础。     

Repetitive DNA sequences located in the central region of the human mdr1 (multidrug resistance) gene may account for a gene fusion event during its evolution

The mdr1 gene, first member of the human multidrug-resistance gene family, is a major gene involved in cellular resistance to several drugs used in anticancer chemotherapy. Its product, the drug-excreting P-glycoprotein, shows a bipartite structure formed by two similar adjacent halves. According to one hypothesis, the fusion of two related ancestral genes during evolution could have resulted in this structure. The DNA sequence analysis of the introns located in the region connecting the two halves of the human mdr1 gene revealed a highly conserved poly(CA) · poly (TG) sequence in intron 15 and repeated sequences of the Alu family in introns 14 and 17. These repeated sequences most likely represent molecular fossils of ancient DNA elements which were involved in such a recombination event. Correspondence to: M. Pauly     

三种壁虎染色体核仁组织者的银染色观察与蹼壁虎的核型

本文以骨髓细胞为材料, 采用常规制片法和一步银染色技术,首次报道了无蹼壁虎、铅山壁虎和多疣壁虑的NORs,并用α-巯基乙醇短期培养无蹼壁虎的骨髓细胞,分析其核型。结果表明,3种壁虎都仅显示一对NORs,也未见有融合现象。其中无蹼壁虎的NORs位于第18对染色体的次缢痕区,而铅山壁虎和多疣壁虎分别位于第19对和第14对上。另外,我们从C带分析中发现,铅山壁虎和多疣壁虎的NORs位点均为结构异染色质区。经α-巯基乙醇培养的无蹼壁虎的染色体明显“拉长”。具次缢痕的染色体可从以往报道的第 19 对调整为第18对,其次缢痕区也比直接制作的标本大而清晰。     

Genetics and cytology of a new genic male-sterile soybean [Glycine max (L.) Merr.]

 Genetic and cytological studies were conducted with a new male-sterile, female-fertile soybean [Glycine max (L.) Merr.] mutant. This mutant was completely male sterile and was inherited as a single-recessive gene. No differences in female or male gamete transmission of the recessive allele were observed between reciprocal cross-pollinations in the F₁ or F₂ generations. This mutant was not allelic to any previously identified soybean genic male-sterile mutants: ms1, ms2, ms3, ms4, ms5, or ms6. No linkage was detected between sterility and flower color (W1 locus), or between sterility and pubescence color (T1 locus). Light microscopic and cytological observations of microsporogenesis in fertile and sterile anthers were conducted. The structure of microspore mother cells (MMC) in male-sterile plants was identical to the MMCs in male-fertile plants. Enzyme extraction analyses showed that there was no callase activity in male-sterile anthers, and this suggests that sterility was caused by retention of the callose walls, which normally are degraded around tetrads at the late tetrad stage. The tapetum from male-sterile anthers also showed abnormalities at the tetrad stage and later stages, which were expressed by an unusual formation of vacuoles, and by accumulation of densely staining material. At maturity, anthers from sterile plants were devoid of pollen grains. Received: 13 May 1996 / Revision accepted: 19 August 1996     

金丝猴属的DNA序列变异及进化与保护遗传学研究

金丝猴的分类及系统发育存在许多争议。本文测定了２只川金丝猴、８只滇金丝猴、１只越南金丝猴和１只灰叶猴的２５３ｂｐ的线粒体细胞色素ｂ基因的序列。其中４７个位点（１９％）检出变异。我们采用简约法、最大似然法和距离法构建了一系列的分子系统树,得到相同的拓扑结构,从而可能在分子水平澄清了金丝猴属的系统发育。结果表明,云南金丝猴与越南金丝猴间的关系较与川金丝猴的为近。金丝猴属的分化大约发生在２～６百万年以前。这３种金丝猴均是独立的种,且都应归入金丝猴属。对８只来自野外的滇金丝猴（其中包括了昆明动物研究所圈养群体的所有６只创立者）的非损伤性遗传分析提示,编号为ＹＫ２的母猴是维持该圈养群体遗传多样性的关键猴。我们建立的这种非损伤性遗传分析方法广泛适用于珍稀濒危动物的遗传多样性及遗传管理研究。     

Binding of simple carbohydrates and some N-acetyllactosamine-containing oligosaccharides to Erythrina cristagalli agglutinin as followed with a fluorescent indicator ligand

Erythrina cristagalli agglutinin, a dimeric lectin [J. L. Iglesias, et al. (1982) Eur. J. Biochem.123, 247–252] was shown by equilibrium dialysis to be bivalent for 4-methylumbelliferyl-β-d-galactoside. Upon binding to the lectin, this ligand showed a difference absorption spectrum with two maxima (at 322 and 336 nm) of equal intensity (Δ? = 1.2 × 10³m^?1 cm^?1). A similar spectrum with a comparable value of Δ? was obtained with 4-methylumbelliferyl-N-acetyl-β-d-galactosaminide. Binding of methyl-α-d-galactoside, lactose, and N-acetyllactosamine all produced small but equally intense protein difference spectra with a maximum (Δ? = 2.8 × 10² M^?1 cm^?1) at 291.6 nm. Upon binding of N-dansyl-d-galactosamine to the lectin, there was a fivefold increase in fluorescence intensity of this ligand. The association constant for N-dansyl-d-galactosamine was caused by a very favorable ΔS° of the dansyl group without affecting the strictly carbohydrate-specific character of binding. N-Dansyl-d-galactosamine was employed as a fluorescent indicator ligand in substitution titrations. This involved the use of simple carbohydrates, N-acetyllactosamine, and oligosaccharides which occur in the carbohydrate units of N-glycoproteins; the latter were Gal(β → 4)GlcNAc(β1 → 2)Man, Gal(β1 → 4)GlcNAc(β1 → 6)Man, and Gal(β1 → 4)GlcNAc(β1 → 6)[Gal(β1 → 4)GlcNAc(β1 → 2)]Man. The titrations were performed at two temperatures to determine the thermodynamic parameters. In the series N-acetyl-d-galactosamine, methyl-α-d-galactoside, and lactose, ?ΔH° increased from 24 to 41 kJ mol^?1; it increased further for N-acetyllactosamine and then remained unchanged for the N-acetyllactosamine-containing oligosaccharides (55 ± 1 kJ mol^?1). This indicated that the site specifically accommodated the disaccharide structure with an important contribution of the 2-acetamido group in the penultimate sugar. Beyond this, no additional contacts seemed to be formed. This conclusion also followed from considerations of ΔS° values which became more unfavorable in the above series (?23 to ?101 ± 4 J mol^?1 K^?1); the most negative value of ΔS° was observed with N-acetyllactosamine and the three N-acetyllactosamine-containing oligosaccharides.     

Patterns of cell polarity in the developing mouse limb

Most cells have a morphological polarity with the centrioles and Golgi apparatus occupying one pole of the cell and the nucleus the other. This structural polarity often correlates with functional polarity as in secretory epithelia where the Golgi apparatus moves to the pole of the cell from which secretory materials are exreted. In limb development an interaction of unknown mechanism occurs between the epithelium and mesenchyme. We have evaluated the pattern of cell polarity using silver impregnation of the Golgi apparatus in limb epithelium and mesenchyme of mouse embryos from day 9.5, when limbs are first visible, to day 15, when cartilage formation is complete. Cells in the epithelium almost always have the Golgi apparatus in the apex of the cell, i.e., oriented away from the basement membrane. The layer of mesenchyme cells just beneath the basement membrane initially has only 16 to 25% of the cells oriented toward the basement membrane. A marked shift in orientation occurs between days 12 and 13 so that from days 13 to 15 up to 53% of the mesenchyme cells are oriented toward the basement membrane. This shift in orientation occurs more slowly in the mesenchyme at a depth of four cells below the basement membrane. This changing pattern of mesenchymal cell polarity occurs at a time when there is an apparent increase in the amount of extracellular matrix, especially in the region just below the basement membrane.     

An experimental test of the efficiency of family selection in chickens

Summary Responses to single trait selection on individual phenotype and sire-family mean phenotype for survivor's egg weight and rate of lay were measured for a single generation in 13 replicates. Each replicate-selection criterion-trait subclass consisted of eight sire families or 72 females measured and was reproduced from the best 25% of the families or individuals. The realized heritability of egg weight was 0.39 and that of rate of lay was 0.31, both of which were significantly greater than zero but not significantly different from the predicted values based on halfsib correlations in the base population.The standardized response to sire-family selection was less than the response to individual selection for both traits and the difference was significant for rate of lay (0.10; 0.31) but not for egg weight (0.22; 0.39). The predicted responses to sire-family selection were less than those for individual selection for both traits, and the observed responses to sire-family selection were not significantly different from the predicted values for either trait.These experimental results do not disagree with the theoretical expectations of the relative efficiencies of individual and sire-family selection.Journal paper no. 7479, Purdue University, Agricultural Experiment Station. This investigation was conducted as a part of the cooperative research of the NC-89 Regional Poultry Breeding Project entitled Nature and Utilization of Genetic Variation in Poultry Improvement     

Frequency changes with time in vivo of radiation-induced chromosomal aberrations in skin fibroblasts

5 Syrian hamster litter mates were each irradiated with X-rays on one flank to 300 rad. Skin biopsies were taken from both the irradiated and unirradiated (control) flanks of each animal at one day and at about 6 months after irradiation. The cells cultured from these biopsies were used to determine the frequencies of chromosomal aberrations. During the 6-month period there were significant reductions in the frequencies of both reciprocal translocations and terminal deletions.

Translocations involving the short arm of the Y-chromosome, however, showed a significant increase during this period.

It is possible that while the latter phenomenon was due to cell selection in vivo the general fall off in translocations and deletions was the result of a long term in vivo repair mechanism or perhaps the results of certain aberrations proving to be lethal with prolonged expression times.     

Genetics of seed-coat colour in Citrullus lanatus (Thunb.) Mansf.

Summary Intervarietal crosses in watermelon, Citrullus lanatus (Thunb.) Mansf., involving six parents with black (J18-1 and J 75), brown (J56-1 and N.H. Midget), red (Bykovski-199) or light cream (Red Nectar) seed-coat colour were made. Parents, F₁, F₂ and backcross populations were evaluated for their phenotypic expressions with regard to the seed-coat colours involved. Black colour was monogenically dominant over brown light cream and red colour of seed-coat separately or independently. Red colour was dominant over light cream colour of seed-coat by a single pair of genes. The light cream colour was recessive to the brown seed-coat colour of watermelon where a single pair of genes was involved.