红原鸡与家鸡的亲缘关系研究

对中国红原鸡滇地亚种和海南亚种与我国茶花鸡,泰和鸡和寿光鸡等地方鸡种以及芦花鸡,洛岛红等外国鸡种进行了血型（３个位点,１３个等位基因）,蛋白质（酶）多态（５个位点,１１个等位基因）和ＤＮＡ指纹分析,结果表明,红原鸡与茶花鸡（原始型品种）的亲缘关系较近;与泰和鸡,寿光鸡,芦花鸡,洛岛红（进化型品种）的亲缘关系较远,呈红原鸡－茶花鸡－泰和鸡,寿光鸡或芦花鸡,洛岛红这样一个进化阶梯,以上结果与国外资料（     

Genetic fingerprinting of pigeonpea [Cajanus cajan (L.) Millsp.] and its wild relatives using RAPD markers

Randomly amplified polymorphic DNA (RAPD) markers were used for the identification of pigeonpea [Cajanus cajan (L.) Millsp.] cultivars and their related wild species. The use of single primers of arbitrary nucleotide sequence resulted in the selective amplification of DNA fragments that were unique to individual accessions. The level of polymorphism among the wild species was extremely high, while little polymorphism was detected within Cajanus cajan accessions. All of the cultivars and wild species under study could be easily distinguished with the help of different primers, thereby indicating the immense potential of RAPD in the genetic fingerprinting of pigeonpea. On the basis of our data the genetic relationship between pigeonpea cultivars and its wild species could be established.NCL Communication No. 6062     

INFLUENCE OF FLUCTUATING PHOSPHATE SUPPLY ON THE REGULATION OF PHOSPHATE UPTAKE BY THE BLUE-GREEN ALGA ANACYSTZS NIDULANS1

The blue-green alga Anacystis nidulans Drouet (Synechococcus leopoliensis Raciborski) cultivated under phosphate-limited conditions adopts a threshold value in the nanomolar range below which uptake ceases. In this study, we investigated the influence of phosphate pulses on the regulation of uptake behavior during reestablishment of the threshold value. Short-term pulses had only a slight effect on uptake kinetics and, hence, on the threshold value, even if the population had been exposed several times to elevated concentrations above the steady-state level in the growth medium. The threshold value was also practically insensitive to the amount of phosphate stored during these short-term fluctuations. Long-term phosphate pulses resulted in a transition to a metastable state that was characterized by a severalfold higher threshold value. This transition, apparently an adaptation to the transiently elevated phosphate concentrations, was further studied by following the influx of ³²P-phosphate at constant external concentrations and was shown to be complete after a period of 10–20 min. After adaptation to pulses, the uptake behavior followed a linear flow-force relation over a wide range of external concentrations. This behavior was explained by the simultaneous operation of at least two uptake systems with different, but coordinated kinetic parameters. This linear flow-force relation facilitated a direct determination of the threshold value from uptake measurements. For applicability in the field the force-flow relation can be a diagnostic tool to assay for fluctuating phosphate and to establish threshold values below the normal measurable range .     

Root to shoot ratio of crops as influenced by CO2

Crops of tomorrow are likely to grow under higher levels of atmospheric CO₂. Fundamental crop growth processes will be affected and chief among these is carbon allocation. The root to shoot ratio (R:S, defined as dry weight of root biomass divided by dry weight of shoot biomass) depends upon the partitioning of photosynthate which may be influenced by environmental stimuli. Exposure of plant canopies to high CO₂ concentration often stimulates the growth of both shoot and root, but the question remains whether elevated atmospheric CO₂ concentration will affect roots and shoots of crop plants proportionally. Since elevated CO₂ can induce changes in plant structure and function, there may be differences in allocation between root and shoot, at least under some conditions. The effect of elevated atmospheric CO₂ on carbon allocation has yet to be fully elucidated, especially in the context of changing resource availability. Herein we review root to shoot allocation as affected by increased concentrations of atmospheric CO₂ and provide recommendations for further research. Review of the available literature shows substantial variation in R:S response for crop plants. In many cases (59.5%) R:S increased, in a very few (3.0%) remained unchanged, and in others (37.5%) decreased. The explanation for these differences probably resides in crop type, resource supply, and other experimental factors. Efforts to understand allocation under CO₂ enrichment will add substantially to the global change response data base.Abbreviations R:S root to shoot ratio, dry weight basis     

Structural Comparisons of Muscle and Nonmuscle Actins Give Insights Into the Evolution of Their Functional Differences

Actin is a highly conserved protein although many isoforms exist. In vertebrates and insects the different actin isoforms can be grouped by their amino acid sequence and tissue-specific gene expression into muscle and nonmuscle actins, suggesting that the different actins may have a functional significance. We ask here whether atomic models for G- and F-actins may help to explain this functional diversity. Using a molecular graphics program we have mapped the few amino acids that differ between isoactins. A small number of residues specific for muscle actins are buried in internal positions and some present a remarkable organization. Within the molecule, the replacements observed between muscle and nonmuscle actins are often accompanied by compensatory changes. The others are dispersed on the protein surface, except for a cluster located at the N-terminus which protrudes outward. Only a few of these residues specific for muscle actins are present in known ligand binding sites except the N-terminus, which has a sequence specific for each isoactin and is directly implicated in the binding to myosin. When we simulated the replacements of side chains of residues specific for muscle actins to those specific for nonmuscle actins, the N-terminus appears to be less compact and more flexible in nonmuscle actins. This would represent the first conformational grounds for proposing that muscle and nonmuscle actins may be functionally distinguishable. The rest of the molecule is very similar or identical in all the actins, except for a possible higher internal flexibility in muscle actins. We propose that muscle actin genes have evolved from genes of nonmuscle actins by substitutions leading to some conformational changes in the protruding N-terminus and the internal dynamics of the main body of the protein. Received: 15 March 1996 / Accepted: 14 July 1996     

两种吸血水蛭对光闪烁和水扰动刺激的反应

利用自制的控温实验槽在暗室内进行医蛭科两种吸血水蛭对光闪烁和水扰动刺激的模拟个体生态实验,实验结果的统计分析表明,日本医蛭在１６℃时与照度有极好的正相关关系,而在２２℃时成负相关关系,０．２克体重的个体在两种温度对照度的敏感度均大于０．５－０．６克和１．０－１．３克体重的个体,湖北牛蛭在两种温度时与照度均成正相关关系;０．５克体重的个体在１６℃时对照度的敏感度大于１．０－３．３克体重的个体９．５－     

鸡爪草属的染色体及其系统位置

本文研究了毛茛科鸡爪草Calathodes oxycarpa的核形态。其静止核和有丝分裂前期染色体分别属于复杂中央染色微粒型和中间型,中期染色体属于R型,核型公式为2n=16=8sm 8st(2sat)。据此并结合有关资料,讨论了鸡爪草属与毛茛科其它类群的亲缘关系,认为鸡爪草属与金莲花属和特产于南朝鲜的Megaleranthis属是极为近缘的类群,不宜将它们分开置于不同的族或亚科中。     

Steady-state kinetics of the overall oxidative phosphorylation reaction in heart mitochondria. Determination of the coupling relationships between the respiratory reactions and miscellaneous observations concerning rate-limiting steps

The linear sequence of steps involved in the oxidation of extramitochondrial succinate by O₂ in bovine heart mitochondria was examined by a steady-state kinetic method to determine whether or not freely diffusible intermediates occur between the various inhibitor-sensitive steps. The kinetic method is based on the facts (1) that if two inhibitor-sensitive steps within a sequence are linked by a freely diffusible intermediate, inhibition of one will make the other less rate limiting in the overall reaction and thus will increase the amount of inhibitor of the other step required for half-maximal inhibition of the overall reaction, and (2) that if the two steps are not linked in this manner, inhibition of one will make the other more rate limiting and thus will decrease the amount of inhibitor of the other required for half-maximal inhibition. These two types of coupling relationships between steps were designated as sequential and fixed, respectively. The results indicate the existence of freely diffusible intermediates (sequential coupling relationships) between the succinate transport and succinate dehydrogenase reactions, between the succinate dehydrogenase and cytochromebc ₁ reactions, and between the cytochromesbc ₁ andaa ₃ reactions. Uncoupling respiration from phosphorylation results in the coupling relationship between thebc ₁ andaa ₃ reactions becoming partially fixed. This change is accompanied by marked decreases in the degrees to which thebc ₁ andaa ₃ reactions limit the overall reaction and appears to account for the large uncoupler-induced releases of inhibition at the levels of thebc ₁ andaa ₃ reactions observed previously by others. It is suggested that cytochromec is the freely diffusible intermediate between thebc ₁ andaa ₃ reactions and that the uncoupler-induced changes occur as a result of formation of functional and highly efficient supercomplexes between cytochromec and the cytochromesbc ₁ andaa ₃ complexes.     

Phloem unloading and ‘sink strength’: The parallel between the site of attachment of Cuscuta and developing legume seeds

Sink regions play a central role in determining assimilate distribution patterns. Two factors are discussed which have a strong effect on the sink strength of a sink, viz. phloem unloading and turgor-sensitive transport. Sink strength may be defined as the capacity of phloem in the sink region to import assimilates from other parts of the plants and to release the imported substances into the sink apoplast.A stem parasitized by Cuscuta represents a very strong sink. A review is presented of data on enhanced phloem unloading, at the site of attachment of Custuta. Recent data on metabolically controlled sucrose and amino acid unloading into the seed coat apoplast of developing legume seeds show a remarkable parallel with phloem unloading in a parasitized Vicia faba stem. Data on turgor-sensitive sucrose and amino acid transport into developing seeds are presented, which throw new light on the pressure flow theory of phloem transport.     

Utilisation of wild relatives in the genetic improvement of Arachis hypogaea L.

Summary Cross-compatibility of species in section Arachis Krap. et Greg. nom. nud., and chromosome pairing and pollen fertility in their interspecific F₁ hybrids were studied to further understand the phylogenetic relationships among these species. Except those with A. batizocoi Krap. et Greg. nom. nud., hybrids between diploid species have near normal bivalent frequency (9.1–9.8) and moderate to high pollen fertility (60–91%). Hybrids between A. batizocoi and other species have low bivalent frequency (5.2–6.9) and very low pollen fertility (3–7%). These results confirm the earlier separation of these species into two groups based on karyomorphology and Mahalanobis D² calculated on arm ratios. These studies also provide a picture of relative affinities between A. batizocoi, the lone member of one cluster, and the other species, and among the rest of the species. They also indicate that the basic chromosome complement in the two groups of species is the same. Chromosome pairing in triploid hybrids, (A. hypogaea L. X diploid wild species), suggests that A. batizocoi is the closest diploid relative of A. hypogaea. It is closer to A. hypogaea subspecies fastigiata Waldron than to A. hypogaea subspecies hypogaea Krap. et. Rig. Other diploid species of the section Arachis are equidistant from A. hypogaea, and have the same genome which has strong homology to one of the genomes of A. hypogaea. Based on the present results, the two tetraploid species, A. monticola Krap. et Rig. and A. hypogaea can be recognised as two forms of the same species. Breeding implications have been discussed in the light of chromosome behaviour observed in hybrids of A. hypogaea X diploid species, and on the presumptions that A. hypogaea has an AABB genomic constitution, and that among the diploid species, the B genome is present in A. batizocoi while the A genome is common to the other diploid species of section Arachis.Submitted as Journal Article No. 328 by the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT)