Studies on the energy coupling sites of photophosphorylation IV. The relation of proton fluxes to the electron transport and ATP formation associated with Photosystem II

1. By using dibromothymoquinone as the electron acceptor, it is possible to isolate functionally that segment of the chloroplast electron transport chain which includes only Photosystem II and only one of the two energy conservation sites coupled to the complete chain (Coupling Site II, observed P/e₂ = 0.3–0.4). A light-dependent, reversible proton translocation reaction is associated with the electron transport pathway: H₂O → Photosystem II → dibromothymoquinone. We have studied the characteristics of this proton uptake reaction and its relationship to the electron transport and ATP formation associated with Coupling Site II.

2. The initial phase of H⁺ uptake, analyzed by a flash-yield technique, exhibits linear kinetics (0–3 s) with no sign of transient phenomena such as the very rapid initial uptake (“pH gush”) encountered in the overall Hill reaction with methylviologen. Thus the initial rate of H⁺ uptake obtained by the flash-yield method is in good agreement with the initial rate estimated from a pH change tracing obtained under continuous illumination.

3. Dibromothymoquinone reduction, observed as O₂ evolution by a similar flash-yield technique, is also linear for at least the first 5 s, the rate of O₂ evolution agreeing well with the steady-state rate observed under continuous illumination.

4. Such measurements of the initial rates of O₂ evolution and H⁺ uptake yield an H⁺/e⁻ ratio close to 0.5 for the Photosystem II partial reaction regardless of pH from 6 to 8. (Parallel experiments for the methylviologen Hill reaction yield an H⁺/e⁻ ratio of 1.7 at pH 7.6.)

5. When dibromothymoquinone is being reduced, concurrent phosphorylation (or arsenylation) markedly lowers the extent of H⁺ uptake (by 40–60%). These data, unlike earlier data obtained using the overall Hill reaction, lend themselves to an unequivocal interpretation since phosphorylation does not alter the rate of electron transport in the Photosystem II partial reaction. ADP, P_i and hexokinase, when added individually, have no effect on proton uptake in this system.

6. The involvement of a proton uptake reaction with an H⁺/e⁻ ratio of 0.5 in the Photosystem II partial reaction H₂O → Photosystem II → dibromothymoquinone strongly suggests that at least 50% of the protons produced by the oxidation of water are released to the inside of the thylakoid, thereby leading to an internal acidification. It is pointed out that the observed efficiencies for ATP formation (P/e₂) and proton uptake (H⁺/e⁻) associated with Coupling Site II can be most easily explained by the chemiosmotic hypothesis of energy coupling.     

Inbreeding trends and genetic diversity in purebred sheep populations

Monitoring the rate of change in inbreeding and genetic diversity within a population is important to guide breeding programmes. Such interest stems from the impact of loss in genetic diversity on sustainable genetic gain but also the impact on performance (i.e. inbreeding depression). The objective of the present study was to evaluate trends in inbreeding and genetic diversity in 43 066 Belclare, 120 753 Charollais, 22 652 Galway, 78 925 Suffolk, 187 395 Texel, and 19 821 Vendeen purebred sheep. The effective population size for each of the six breeds was between 116.0 (Belclare population) and 314.8 (Charollais population). The Charollais population was the most genetically diverse with the greatest number of effective founders, effective ancestors, and effective founder genomes; conversely, the Belclare was the least genetically diverse population with the fewest number of effective founders, effective ancestors, and effective founder genomes for each of the six breeds investigated. Overall, the effective population sizes and the total genetic diversity within each of the six breeds were above the minimum thresholds generally considered to be required for the long-term viability of a population.     

Estimating effective paternity number in social insects and the effective number of alleles in a population

Estimating paternity and genetic relatedness is central to many empirical and theoretical studies of social insects. The two important measures of a queen's mating number are her actual number of mates and her effective number of mates. Estimating the effective number of mates is mathematically identical to the problem of estimating the effective number of alleles in population genetics, a common measure of genetic variability introduced by Kimura & Crow (1964). We derive a new bias-corrected estimator of effective number of types (mates or alleles) and compare this new method to previous methods for estimating true and effective numbers of types using Monte Carlo simulations. Our simulation results suggest that the examined estimators of the true number of types have very similar statistical properties, whereas the estimators of effective number of types have quite different statistical properties. Moreover, our new proposed estimator of effective number of types is approximately unbiased, and has considerably lower variance than the original estimator. Our new method will help researchers more accurately estimate intracolony genetic relatedness of social insects, which is an important measure in understanding their ecology and social behaviour. It should also be of use in population genetic studies in which the effective number of alleles is of interest.     

Evolutionary dynamics of zero-sum games

Aim model in terms of differential equations is used to explain mammalian ovulation control, in particular regulation for a prescribed number of mature eggs. NIH Grant RO1 GM 32153-01GE     

番茄心室形成的遗传规律初探

应用番茄多心室自交系和少心室自交系进行正交、反交及F1代自交和回交,对双亲及获得的正反交F1、F2及回交各世代植株的心室数进行遗传分析。结果表明:少心室为不完全显性,回交效应显著,正反交差异不显著,呈现核遗传,细胞质作用不显著。番茄心室数符合加性-显性模型,以加性效应为主,属不完全显性;控制心室数的最少主基因对数是1对,还受到其他微效基因的控制。番茄心室数广义遗传力为69.44%,狭义遗传力为52.98%。     

正廿面体病毒的三角形剖分数和壳粒数公式的推导

本文对p=h~2+hk+k~2,T=pf~2,C=10T+2和C=10p(n-1)~2+2几个公式进行了新的推导和计算,并对其公式间的关系和每个参数的数学含义作了说明,进而澄清了一些模糊认识,加深了对公式的理解和运用。     

Asian low‐androstenone haplotype on pig chromosome 6 does not unfavorably affect production and reproduction traits

European pigs that carry Asian haplotypes of a 1.94‐Mbp region on pig chromosome 6 have lower levels of androstenone, one of the two main compounds causing boar taint. The objective of our study was to examine potential pleiotropic effects of the Asian low‐androstenone haplotypes. A single nucleotide polymorphism marker, rs81308021, distinguishes the Asian from European haplotypes and was used to investigate possible associations of androstenone with production and reproduction traits. Eight traits were available from three European commercial breeds. For the two sow lines studied, a favorable effect on number of teats was detected for the low‐androstenone haplotype. In one of these sow lines, a favorable effect on number of spermatozoa per ejaculation was detected for the low‐androstenone haplotype. No unfavorable pleiotropic effects were found, which suggests that selection for low‐androstenone haplotypes within the 1.94 Mbp would not unfavorably affect the other eight relevant traits.     

Estimation of the Number of Classes in a Population

The problem of estimating M, the number of classes in a population, is formulated as an occupancy problem in which N items are drawn from M urns. Under the assumption of a uniform distribution for the number of classes in the population, the sufficient statistic for M, which is the number of distinct classes observed, does not depend upon the number of repetitions in the sample. Point and interval estimates of M are developed using maximum likelihood and the method of moments. Both techniques give rise to the same basic equation which requires a simple iterative solution. These same techniques are used in the more general situation in which the classes can be further subdivided according to type.     

不同玉米自交系茎秆上部维管束数目的差异分析

茎秆维管束数目是玉米养分运输和抗倒伏的关键影响因素,本研究以遗传丰富的172份玉米自交系为研究材料,对茎秆上部小维管束和大维管束数目进行差异性分析,并通过不同杂种优势群的玉米茎秆上部维管束数目多重比较,分析各杂种优势群维管束数目变化趋势.研究结果表明:在不同玉米自交系中,茎秆上部小维管束和大维管束数目变异系数分别为16...     

Unusual codon usage bias in low expression genes of Vibrio cholerae

Positive correlation between gene expression and synonymous codon usage bias is well documented in the literature. However, in the present study of Vibrio cholerae genome, we have identified a group of genes having unusually high codon usage bias despite being low potential expressivity. Our results suggest that codon usage in lowly expressed genes might also be selected on to preferably use non-optimal codons to maintain a low cellular concentration of the proteins that they encode. This would predict that lowly expressed genes are also biased in codon usage, but in a way that is opposite to the bias of highly expressed genes.     

Genomic prediction of reproduction traits for Merino sheep

Economically important reproduction traits in sheep, such as number of lambs weaned and litter size, are expressed only in females and later in life after most selection decisions are made, which makes them ideal candidates for genomic selection. Accurate genomic predictions would lead to greater genetic gain for these traits by enabling accurate selection of young rams with high genetic merit. The aim of this study was to design and evaluate the accuracy of a genomic prediction method for female reproduction in sheep using daughter trait deviations (DTD) for sires and ewe phenotypes (when individual ewes were genotyped) for three reproduction traits: number of lambs born (NLB), litter size (LSIZE) and number of lambs weaned. Genomic best linear unbiased prediction (GBLUP), BayesR and pedigree BLUP analyses of the three reproduction traits measured on 5340 sheep (4503 ewes and 837 sires) with real and imputed genotypes for 510 174 SNPs were performed. The prediction of breeding values using both sire and ewe trait records was validated in Merino sheep. Prediction accuracy was evaluated by across sire family and random cross‐validations. Accuracies of genomic estimated breeding values (GEBVs) were assessed as the mean Pearson correlation adjusted by the accuracy of the input phenotypes. The addition of sire DTD into the prediction analysis resulted in higher accuracies compared with using only ewe records in genomic predictions or pedigree BLUP. Using GBLUP, the average accuracy based on the combined records (ewes and sire DTD) was 0.43 across traits, but the accuracies varied by trait and type of cross‐validations. The accuracies of GEBVs from random cross‐validations (range 0.17–0.61) were higher than were those from sire family cross‐validations (range 0.00–0.51). The GEBV accuracies of 0.41–0.54 for NLB and LSIZE based on the combined records were amongst the highest in the study. Although BayesR was not significantly different from GBLUP in prediction accuracy, it identified several candidate genes which are known to be associated with NLB and LSIZE. The approach provides a way to make use of all data available in genomic prediction for traits that have limited recording.     

Estimating a Key Parameter of Mammalian Mating Systems: The Chance of Siring Success for a Mated Male

Studies of multiple paternity in mammals and other animal species generally report proportion of multiple paternity among litters, mean litter sizes, and mean number of sires per litter. It is shown how these variables can be used to produce an estimate of the probability of reproductive success for a male that has mated with a female. This estimate of male success is more informative about the mating system that alternative measures, like the proportion of litters with multiple paternity or the mean number of sires per litter. The probability of success for a mated male can be measured both theoretically and empirically, and gives an estimate of the intensity of sperm competition and of a male's “confidence of paternity” upon mating. The probability of success for mated males for ten “exemplar” species of mammals is estimated and they are compared for insights into the functioning of their mating systems.     

Isolation and characterization of pLS 1 plasmid mutants with increased copy numbers

Abstract Streptococcus pneumoniae genetic systems designed for isolation of plasmid mutants with copy-up phenotypes have been developed. The target plasmids have the pLS1 replicon, and two different strategies have been followed: (i) selection of clones exhibiting augmented resistance to antibiotics, or (ii) obligatory co-existence of incompatible plasmids. We have isolated 23 plasmid mutants exhibiting increased number of copies. All the mutations corresponded to four different alleles of the copG gene of plasmid pLS1. These strategies could be used with other plasmids.     

ATP生物荧光法快速检测化妆品中菌落总数的研究

本文从快速检测的必要性出发,介绍了ATP生物荧光法及其原理,并针对某款化妆品通过一系列实验建立了一种快速检测菌落总数的方法。将该方法用于CTFA(美国化妆品香料香精协会,Cosmetic Toiletry and Fragrance Association)实验中,并通过与平板计数法结果进行比对,发现该方法可以有效的运用于样品细菌总数的快速检测。     

Incorporation of galactose from UDP-galactose into microsomal and golgi membranes of rat liver

Rough and smooth microsomes and Golgi membranes were incubated with UDP[¹⁴C]galactose and the incorporation of radioactivity into the lipid extract and into endogenous protein acceptors were measured. Antagonistic pyrophosphatases were inhibited with ATP and interference from β-galactosidase activity was greatly decreased by carrying out the incubation at pH 7.8. After incubation the particles were centrifuged to remove free oligosaccharide residues. Radioactivity was found in the lipid extract from Golgi membranes but not from rough and smooth microsomes. This radioactivity, however, was not associated with dolichol or retinyl phosphates. The incorporation of radioactivity into proteins of the Golgi fraction was more than double than that of the microsomal fractions. In addition, the transferases in these two types of particles exhibited different properties. Trypsin treatment of intact rough microsomal vesicles, smooth vesicles and Golgi membranes removed about 5, 15 and 50%, respectively, of newly incorporated protein-bound galactose, indicating that the proportion of the newly galactosylated proteins, which are localized at the cytoplasmic surface of the membrane, is lowest in rough microsomes, intermediate in smooth, and highest in Golgi membranes.     

Simple algorithms for the estimation of the initial number of individuals in commingled skeletal remains

The determination of the number of individuals represented within commingled remains is based on two types of estimators, those assessing the minimum number of individuals and those assessing the most likely number of individuals. Much as the latter produce improved results, they still exhibit significant drawbacks, which are related to the misidentification of the number of pairs between the existing bilateral elements. This article addresses these problems through the use of two computer algorithms. One algorithm produces a number of potential pairs between bilateral elements and the other estimates the number of individuals in a commingled sample by incorporating the percentages of lost and altered bones into the analysis. These algorithms were validated using hypothetical and actual skeletal samples, and are more effective in comparison to any conventional estimators, particularly in cases, where the elements are poorly preserved.