The Affected Sib Method. I. Statistical Features of the Affected Sib-Pair Method

The distribution of the number of HLA haplotypes shared by sibs affected with the same HLA-linked disease can be used to obtain information on the genetics of the disease. Since the inception of the use of sib-pair methods for the analysis of the HLA-associated diseases, the question has been raised of how to include families with more than two affected sibs in the sib-pair analysis. This paper presents appropriate weighting schemes. A procedure for estimating the frequency of the disease allele in the general population, under the assumptions of single-allele recessive, additive, dominant and intermediate models, with negligible recombination (theta = 0) between the disease-predisposing gene and the HLA region, and no selective disadvantage of the trait, is also given. Cluster-sampling techniques are used in the analysis.     

Correlated effects of the response to conditioned medium in the flour beetle,Tribolium castaneum

Dispersal rates were measured in lines selected for high and low response of egg production to conditioned media, and responsivness of egg production was measured in lines selected for high and low dispersal. A positive correlation was found between these two traits, each of which had previously been found to have a simple genetic basis. It is suggested that in Tribolium castaneum the sensitivity to environmental conditions is mediated through a Sensor gene, which can activate either response, according to circumstances.     

Spontaneous DNA repair in human mononuclear cells is calcium-dependent

Spontaneous DNA repair in peripheral blood mononuclear cells (PBMC) has been recently described. The aim of this study was to evaluate whether spontaneous DNA repair is Ca(2+)-dependent, as in vitro-stimulated DNA repair. Spontaneous DNA repair in PBMC was measured in a 1mM Ca2+ medium. The effect of extracellular Ca2+ chelation by EGTA, intracellular Ca2+ chelation by bapta-AM, and Ca2+ loading by the ionophore A23187 was examined. The signal transduction pathway was evaluated by inhibiting protein tyrosine kinase with genistein, calmodulin with W7, and calcineurin with cyclosporin A and tacrolimus. Extracellular Ca2+ chelation had no effect on spontaneous DNA repair, while both intracellular chelation and calcium overloading inhibited the DNA repair. Inhibition of protein tyrosine kinase, calmodulin or calcineurin reduced DNA repair. In conclusion, spontaneous DNA repair is mainly Ca(2+)-dependent at a narrow range of intracellular Ca2+ concentrations. The signal transduction cascade includes protein tyrosine kinase, calmodulin, and calcineurin.     

Summer heat stress alters the mRNA expression of selective-uptake and endocytotic receptors in bovine ovarian cells

Summer heat stress (HS) is a major factor in decreased reproductive performance in high-producing dairy cattle, possibly by affecting the steroidogenic capacity of ovarian follicles and ovarian follicular dynamics. In the present study, mRNA expression of cholesterol receptors was determined in bovine ovarian cells. Two endocytotic receptors (very-low-density lipoprotein receptor (VLDLr) and low-density lipoprotein receptor (LDLr)), and two selective-uptake receptors (scavenger receptor class B type 1 receptor (SRB1) and the lipoprotein-receptor-related protein 8 (LRP8)) were evaluated. Ovarian follicles in four diameter categories were evaluated from cows under non-heat stress (NHS) and HS conditions. As follicle size increased, expression of mRNA in NHS cows increased for the selective-uptake receptors, SRB1 and LRP8, and decreased (P<0.004) for the endocytotic receptors, LDLr and VLDLr. In contrast, in HS cows, mRNA expression did not significantly change (with increasing follicle diameter) for either receptor type. With increasing follicle diameter, cholesterol and fatty acid concentrations in the follicular fluid did not change in HS cows, whereas in NHS cows, cholesterol increased (P<0.008) and fatty acid decreased (P<0.0001). These changes paralleled those in the different lipoprotein fractions in the follicular fluid. In follicles from HS cows, the altered mRNA expression patterns for the endocytotic and selective-uptake receptors caused changes in the regulation of cholesterol supply at critical stages of folliculogenesis, which may play a role in the low turnover rates of ovarian follicles during the summer.     

Inability of Ceratitis capitata (Diptera: Tephritidae) to overwinter in the Judean hills

The overwintering potential of the Mediterranean fruit fly, Ceratitis capitata (Wiedemann) (Diptera: Tephritidae), in cold winter areas within its northern distribution is a key element in understanding its ecology. Recent studies have suggested that although originating in tropical Africa, the fly has become adapted to the cold weather that prevails within its northernmost areas of distribution. We address the question of whether the Mediterranean fruit fly has expanded its overwintering range to include the mountains of central Israel. Doing so would imply that the fly has developed either a behavioral or a physiological mechanism to cope with low temperature and/or damp conditions in combination with cold. We monitored adult populations year round, sampling fruit, calculating expected emergence days for overwintering flies, and studying adults captured within dense and sparse apple orchards. We also performed several manipulative experiments to study preimago ability to survive the winter under natural or seminatural conditions. The study was conducted in the central mountains of Israel at 700-m altitude from 1994 to 2003. Comparison experiments also were conducted at 400 m and at sea level. Our results show 1) no adults captured during the winter and spring, 2) an absence of new infestations during the winter and spring, and 3) inability of preimago stages to overwinter in the central mountains of Israel. Thus, we conclude that the fly does not overwinter in the central mountains of Israel. We discuss the ecological and applied significance of our findings.     

Inhibition of interleukin-10 by the immunomodulator AS101 reduces mesangial cell proliferation in experimental mesangioproliferative glomerulonephritis: association with dephosphorylation of STAT3

Mesangial cell (MC) proliferation is essential for the pathogenesis and progression of glomerular disease. Using an acute model of mesangial proliferative glomerulonephritis (Thy1 GN), we show that neutralization of interleukin (IL)-10 greatly ameliorated the disease as expressed by both decreased MC expansion and proteinuria. Treatment with the tellurium compound AS101 (ammonium trichloro(dioxoethylene-o,o')tellurate) resulted in favorable effects provided that the compound was administered 24 h before insult, whereas partial effects were obtained when administered after insult. We identified STAT3 as playing a pivotal role in IL-10-induced MC proliferation in vitro and in vivo. IL-10 activates MC STAT3 in vitro as expressed by its phosphorylation and nuclear translocation. The role of STAT3 in MC proliferation induced by IL-10 was deduced from results showing that IL-10-induced proliferation was abrogated if MC transfected with STAT3 antisense oligonucleotides were used or if cells were incubated with inhibitors of STAT3. AS101 deactivates STAT3 in control but not in MC transfected with IL-10 antisense oligonucleotides. Inactivation of STAT3 prevents reduction of MC proliferation by AS101. We further demonstrate the role of STAT3 in the regulation of cell cycle and survival regulatory proteins by AS101 in MC via inhibition of IL-10. IL-10 increased MC expression of Bcl-2 and Bcl-X1 and simultaneously decreased the levels of p27kip1. These survival factors were decreased by AS101 in a STAT3- and IL-10-dependent manner, whereas p27kip1 was similarly increased. In Thy1 GN, phosphorylated STAT3 in glomerular MC peaked at day 6 and correlated with MC expansion. Neutralization of IL-10 or its inhibition by AS101 abolished phosphorylation of STAT3. This effect positively correlated with amelioration of the disease. These in vitro and in vivo studies indicate that the autocrine MC growth factor IL-10 induces MC proliferation via STAT3. We suggest that IL-10 or its downstream target STAT3 might be therapeutic targets for kidney diseases induced by mesangial proliferation.     

Time-dependent animal conflicts: 2. The asymmetric case

This paper presents an asymmetric game-theoretical model to the following type of animal conflicts: a member of a group is at risk and needs the help of another member to be saved. As long as assistance is not provided, this individual has a positive, time-dependent rate of dying. Assisting the individual which is at risk accrues a cost, but losing it decreases each member's inclusive fitness. A potential helper's interval between the moment a group member gets into trouble and the moment it assists is a random variable, hence its strategy is to choose the distribution of this random variable. In the asymmetric conflict all the potential helpers have identical strategy sets, but each plays a different role. For example, male or female and young or old. We consider both payoff-irrelevant asymmetry and payoff-relevant asymmetry and characterize each role's stable replies. The evolutionarily stable strategies (ESS) are computed, and the model is applied to the n brothers' problem. According to our results immediate assistance and no assistance are possible ESS both under payoff-relevant asymmetry and under payoff-relevant asymmetry.     

Biosynthesis of triterpenoid sapogenols in soybean and alfalfa seedlings

By incubation of germinating soybeans with mevalonate-[2-¹⁴C] (MVA), radioactivity was incorporated into four sapogenols which were identified by TLC. Unequivocal evidence for the identity of three of the four sapogenols was provided by co-crystallization to constant specific radioactivity. The partition of incorporated radioactivity into lipid- and water-soluble fractions and the pattern of radioactivity of individual sapogenols varied with the mode of administering labeled substrates to soybean seedlings, such as incubation of germinating soybeans with MVA-[2-¹⁴C], immersion of roots into MVA-[2-¹⁴C] or foliar application of squalene-[¹⁴C]. When alfalfa seedlings were incubated with MVA-[2-¹⁴C], about two-thirds of the radioactivity incorporated into the sapogenols was associated with medicagenic acid.     

A mitotically unstable supernumerary chromosome with an accumulation mechanism in a grasshopper

Summary A population of the grasshopper Calliptamus palaestinensis Bdhr. from near Jerusalem, Israel was analyzed cytologically. Twenty-two percent of the males had extra heterochromatic chromosome segments or supernumerary chromosomes. The extra segments were present in either a heterozygous or a homozygous condition and in frequencies similar to those expected according to the Hardy-Weinberg law.The supernumeraries were heteropycnotic in the first meiotic division but paired and segregated regularly. In almost all the males with supernumeraries the number of supernumeraries varied between follicles in the testes but was constant within each follicle. Only 12.3% of the males had supernumeraries, but among those with supernumeraries the majority had means higher than 1.5. A calculation based on the frequency of the supernumeraries in the zygotes which are expected in the next generation indicated that of the 31 males with supernumeraries, probably not more than 3 males originated from zygotes with more than a single supernumerary. The variation in the number of supernumeraries and the high means probably resulted from preferential non-disjunction of the supernumeraries in the early mitoses prior to the differentiation of the follicles.Mitotic non-disjunction of supernumeraries as the cause of intra-individual variation is considered. It is suggested that variation due to non-disjunction would be maintained only in association with accumulation mechanisms.Postdoctoral Trainee in Biology, U. S. Public Health Service, 1962–1963.