Genetic architecture of yield and components of yield in mustard (Brassica juncea (L.) Czern & Coss.)

Summary The relative ability of cross- and self-pollen to achieve fertilisation in Brassica was studied by making double pollinations using cross-pollen carrying a dominant seedling marker gene. With simultaneous self- and crosspollination 12–40% self-seed was set, but when cross-pollen was applied to the stigma four hours before self-pollen, only 2–4% self-seed was obtained. In two plants to which cross-pollen was applied at various time intervals after self-pollen there was a tendency for the percentage of self-seed to increase as the time interval increased. In a third plant this trend was not apparent, probably because of a greater degree of self-incompatibility. The competitive advantage of the first pollen to arrive on the stigma is discussed in relation to the strength of the self-incompatibility and the sib problem in F₁ hybrid brassicas.     

Immunoelectrophoretic analysis of seed proteins from Pisum sativum L.

Summary Soluble proteins of pea seed were investigated by quantitative immunological methods. Vicilin, legumin, pea seed lectin (PEA), 26 albumins and a globulin (B₁) were detected and observed during seed development, germination and under different extraction and fractionation procedures. Vicilin and legumin were found to be immunologically distinctly different. Legumin was found to be comprised of two similar proteins, Legumin species I and II. Vicilin, but no legumin, was detected in the embryonic axis.Three albumins, B₁ and PEA were found to be synthesized after the onset of legumin synthesis.Among the pea lines investigated, one line exhibited distinct differences with respect to the albumins and PEA.Some observations indicate that PEA might interact with other seed proteins of pea.     

Alternative risk-taking styles: The case of time-budgeting strategies of terrestrial gastropods

The terrestrial slugs Arion ater, Limax maximus and Ariolimax columbianus have similar morphological designs but differ remarkably in their life history tactics and behavioural time budgets. The adaptive value of particular risk-taking styles was investigated using a comprehensive computer simulation model. The model allowed each species' success (growth rates, food acquisition) and costs (distance travelled, hydration deficits, injury from aggressive encounters) to be evaluated in various types of weather (benign, harsh and surprise). This was interpreted in terms of the species' life history design. In addition, each species was simulated with the behavioural strategy of the other two species substituted for its natural programming. The simulation experiments demonstrated how variations in a few simple rules could lead to divergent cost-benefit consequences. The model also illustrated that coarsely-tuned sensitivity to the environment may be better than finely-tuned responses, depending on the animal's ability to respond quickly and the degree of risk. The simulations suggested that competition has shaped the time-budgeting tactics of A. ater and L. maximus. Each species actually performed better in harsh weather, using the behavioural program of the other. L. maximus is an aggressive species with a narrow, nocturnal activity period. The concentrated activity of L. maximus may allow it to displace competitors more effectively, whereas the broader time span of A. ater's activity may be necessary to avoid L. maximus.     

用于聚合酶链式反应(PCR)引物设计的计算机程序

 本文报道了两个用于PCR引物设计的计算机程序PCRDESN和PCRDESNA。PCRDESN程序主要从以下4个方面评价用户自己设计的一对引物的质量:(1)引物内的碱基反向重复或发夹结构,(2)两个引物之间的碱基互补配对,(3)两个引物之间的同源性,(4)引物的碱基组成及特点和T_m值计算。通过用多例文献发表的及本院有关实验室提供的引物对序列的验证,确定了程序的运算参数,证明该程序能较好地检验引物对的质量和解释某些PCR实验失败的原因。PCRDESNA程序采用逐级优化的方法和比PCRDESN所选用的更严紧的引物选择参数对用户提供的核酸序列进行快速检索,以确定所有可能的和合适的引物对。     

Hexokinase Levels in Discrete Regions of Rat Brain: Evaluation by Quantitative Immuno fluoresence Using Interactive Laser Cytometry and Comparison with Basal Rates of Glucose Utilization

Relative levels of hexokinase (ATP:D-hexose 6-phosphotransferase, EC 2.7.1.1) have been determined in 16 discrete regions of adult rat brain by a quantitative immunofluorescence method. The distribution of immunofluorescence in brain sections was determined by interactive laser cytometry and related to hexokinase content by comparison with standard sections containing known amounts of the enzyme. In many of these regions, referred to here as group I regions, hexokinase content was correlated with previously reported basal rates of glucose utilization. However, several regions (group II regions) in which hexokinase content exceeded that expected from basal rates of glucose utilization were also detected. Compared with the corresponding regions from albino rat brain, higher hexokinase levels were found in the dorsal and ventral lateral geniculate (group I regions) of pigmented Norway rats, a result reflecting previously reported increased glucose utilization by these regions in pigmented rats. There was no difference in hexokinase levels in the superior colliculus, a group II structure, from albino and pigmented rats, a finding implying that a reported increase in rate of glucose utilization in the superior colliculus of pigmented rats is effected without an increase in hexokinase content. It is suggested that group II regions may be adapted to sustain increases in rates of glucose utilization that are, relative to basal rates, considerably greater than those experienced by group I regions.     

Autoradiographic Localization of Dopaminergic and Noradrenergic Receptors in the Bovine Pineal Gland

Dopamine and norepinephrine are involved in regulation of melatonin synthesis in the pineal gland. In bovine pineal gland, D1- and D2-dopaminergic and alpha 1-adrenergic receptors have been characterized pharmacologically in several laboratories, while beta 1-adrenergic receptors have been studied using physiological technique. The current study presents a quantitative autoradiographic analysis of these four dopaminergic and noradrenergic receptors in bovine pineal gland. The density order of the receptors is D1 greater than alpha 1 greater than D2 greater than or equal to beta 1. The Bmax of dopamine D1 receptors is about 5 to 6 times higher than the Bmax for alpha 1-adrenergic receptors and about 20 times higher than the Bmax values for beta 1-adrenergic and D2-dopaminergic receptors. Dopamine D1 receptors are significantly denser in the pineal cortex than in the medulla. Both dopamine receptors are more concentrated in the distal area than in the proximal area (close to the habenula), whereas both noradrenergic receptors are homogeneously distributed along the longitudinal axis. Only D1-dopaminergic receptors display a heterogeneous distribution between the superior and the inferior areas, being denser in the inferior area. The observation of a much higher concentration of D1-dopaminergic receptors relative to the other receptors suggests an important role for dopamine in the regulation of bovine pineal physiology.     

Power of different sampling strategies to detect quantitative trait loci variance effects

Summary Many studies have shown that segregating quantitative trait loci (QTL) can be detected via linkage to genetic markers. Power to detect a QTL effect on the trait mean as a function of the number of individuals genotyped for the marker is increased by selectively genotyping individuals with extreme values for the quantitative trait. Computer simulations were employed to study the effect of various sampling strategies on the statistical power to detect QTL variance effects. If only individuals with extreme phenotypes for the quantitative trait are selected for genotyping, then power to detect a variance effect is less than by random sampling. If 0.2 of the total number of individuals genotyped are selected from the center of the distribution, then power to detect a variance effect is equal to that obtained with random selection. Power to detect a variance effect was maximum when 0.2 to 0.5 of the individuals selected for genotyping were selected from the tails of the distribution and the remainder from the center.     

Statistical analysis of a linkage experiment in barley involving quantitative trait loci for height and ear-emergence time and two genetic markers on chromosome 4

Summary The quantitative traits height and ear-emergence date were analyzed in the F₂ progeny of a cross between a tall winter barley cultivar (Gerbel) and a short spring barley cultivar (Heriot). The trait distributions were found to be related to the genotypes at two biochemical loci, -amylase (Bmy1) and water-soluble protein (Wsp3), which are known to lie on the long arm of chromosome 4. Linkages between each trait and the markers were investigated using normal mixture models. The two parental phenotypes and the heterozygote phenotype of Bmy1 were distinguishable so the model could be used directly to estimate linkage between Bmy1 and a quantitative trait locus (QTL) for height (Height). The Gerbel homozygote and heterozygote phenotype of Wsp3 could not be distinguished and the model was adapted accordingly. The proportion of plants requiring vernalization was consistent with control by two independent genes acting epistatically, and a normal mixture model based on a two-gene hypothesis was fitted to the distribution of ear-emergence date to estimate linkage between the marker loci and a QTL for ear-emergence date (Vrn1). The parameters of each model were the recombination fraction between the marker locus and the QTL and the means and standard deviations associated with each QTL genotype; these were estimated by maximum likelihood. The fitted distributions correspond well to those observed and the order of the loci along the chromosome is inferred to be Height — Vrn1 — Bmy1 — Wsp3, with Wsp3 being the most distal.     

Construction and characterisation of a yeast artificial chromosome library containing three haploid maize genome equivalents

We have constructed a yeast artificial chromosome (YAC) library using high-molecular-weight DNA prepared from agarose-embedded leaf protoplasts of the maize inbred line UE95. This library contains 79 000 clones with an average insert size of 145 kb and should therefore represent approximately three haploid genome equivalents. The library is organised as an ordered array in duplicate microtitre plates. Forty-one pools of DNA from 1920 individual clones have been prepared for rapid screening of the library by the polymerase chain reaction (PCR). Using this approach, together with conventional colony hybridisation, we have been able to identify between one and eight positive clones for every probe used.