Showing papers in "Journal of Genetics in 1987"
TL;DR: The biotechnology the university industrial complex is one book that the authors really recommend you to read, to get more solutions in solving this problem.
94 citations
TL;DR: The iterative two-person Prisoners’ Dilemma game has been generalised to theN-person case and the evolution of cooperation is explored by matching the Tit For Tat (TFT) strategy against the selfish strategy.
Abstract: The iterative two-person Prisoners’ Dilemma game has been generalised to theN-person case. The evolution of cooperation is explored by matching the Tit For Tat (TFT) strategy (Axelrod and Hamilton 1981) against the selfish strategy. Extension of TFT toN-person situations yields a graded set of strategies from the softest TFT, which continues cooperation even if only one of the opponents reciprocates it, to the hardest, which would do so only when all the remaining opponents cooperate. The hardest TFT can go to fixation against the selfish strategy provided it crosses a threshold frequencypc. All the other TFT are invadable by the selfish (D) or the pure defector strategy, while none can invadeD. Yet, provided a thresholdpc is crossed, they can coexist stably withD. AsN, the size of the group increases, the threshold pc also increases, indicating that the evolution of cooperation is more difficult for larger groups. Under certain conditions, only the soft TFT can coexist stably against the selfish strategyD, while the harder ones cannot. An interesting possibility of a complete takeover of the selfish population by successive invasions by harder and harder TFT strategies is also presented.
74 citations
TL;DR: The Green Revolution technology, centered on high-yielding, disease- and insect-resistant rice varieties, has revolutionized rice production since the late 1960s, and has led to political stability and allowed the governments of the developing countries to pay more attention to the pressing needs of economic development.
Abstract: The Green Revolution technology, centered on high-yielding, disease- and insect-resistant rice varieties, has revolutionized rice production since the late 1960s. Many countries in the rice belt of Asia, which used to import large quantities of rice, have become self-sufficient and have some surpluses to export. As a result, rice prices on the international market and in the domestic markets of many countries have fallen, thus helping the purchasing power of weaker sections of these societies. The consequent improvement in food security has led to political stability and allowed the governments of the developing countries to pay more attention to the pressing needs of economic development. Population growth is continuing at more than 2% annually in many developing rice-growing countries. The demand for rice is likely to exceed supply by the year 2000. To feed this growing population, the growth rate of rice production needs to accelerate further. For this we need varieties with higher yield potential, greater yield stability, shorter growth duration, and superior grain quality. Innovative breeding methods and the emerging techniques of biotechnology must supplement the conventional breeding methods in achieving the future rice breeding goals. Rice breeding today is an international effort, involving scientists worldwide.
64 citations
TL;DR: The strong conservation of its inducible properties, of the organisation rather than the primary DNA base sequence and of the pattern of heat shock transcripts of 93D locus in the genusDrosophila point to important but hitherto little understood functions of this locus.
Abstract: One of the major heat shock induced genes ofDrosophila melanogaster is located in the 93D6-7 bands of polytene chromosomes. The 93D locus shows many unique and intriguing features which are reviewed here. This locus is induced selectively and independently of the other heat shock loci by very diverse agents. The heat shock inducibility of this locus shows a remarkable dependence on the developmental history of the organism, its genetic background and other specific inducers of 93D. In all species ofDrosophila so far tested, one of the major heat shock loci is also selectively induced by the same set of 93D inducers and thus this locus is conserved in the genus. However, cloning and molecular characterisation of the primary DNA base sequence of the 93D ofD. melanogaster and the 93D-like locus ofD. hydei (the 2–48C locus) reveal that except for certain small stretches, the primary DNA base sequence of this locus has diverged rapidly. Interestingly, the structural organisation of the 93D ofD. melanogaster and 2–48C ofD. hydei is remarkably similar-both have a 5’ unique sequence followed on the 3’ end by a long stretch of a species-specific repetitive sequence apparently unique to the locus. Heat shock in both cases induces 3 major transcripts: a long 10–12 kb RNA covering the 5’ unique and 3’ repeat part, a 1.9–2.0 kb RNA complementary to the 5’ unique part and a 1.2 kb transcript which lacks the 0.7 kb “intron” of the 2 kb RNA. None of the transcripts in either species has any appreciable open reading frames, and other evidence also suggests that the 93D or 2–48C loci do not code for any polypeptide. Functions of 93D or 93D-like loci remain uncertain although the locus is essential for ecdysone-induced differentiation of imaginal disks and viability of flies. Strong evidence exists that the activity pattern of the 93D heat shock locus inD. melanogaster distinctly influences heat shock puffing of the 87C locus, one of the two duplicate loci carrying the coding sequences for the major 70 kd heat shock polypeptide; presently available evidence suggests that this effect on 87C puffing is mediated via the mid-repetitive and heat-inducibleas sequences residing at the 87C locus. The strong conservation of its inducible properties, of the organisation rather than the primary DNA base sequence and of the pattern of heat shock transcripts of 93D locus in the genusDrosophila point to important but hitherto little understood functions of this locus. The structure of its transcripts may have vital regulatory roles.
33 citations
TL;DR: The balance between the creation of associations between alleles at different loci by immigration and the convergence to linkage equilibrium due to the recombination process is studied in a theoretical model and it is shown that the build-up of the higher order Bennett-disequilibria through the cline is considerably more pronounced than the build up of two-locus disequilibaria.
Abstract: The balance between the creation of associations between alleles at different loci by immigration and the convergence to linkage equilibrium due to the recombination process is studied in a theoretical model. The geographical structure of the model is a stepping-stone chain of populations linking two genetically constant source populations. The model assumes an arbitrary number of autosomal loci and considers genetic variation (two alleles at each locus) that is not subject to natural selection. The gene frequencies at each locus will then show a linear cline through the stepping-stone chain of populations. The deviation from linkage equilibrium through the stepping-stone cline is characterized by an equation for linear measures that provide the linkage disequilibrium measures for a given set of loci in terms of the gene frequencies and the linkage disequilibria in the source populations and in terms of the linkage disequilibrium measures through the cline for lower numbers of loci. Numerical examples of this iterative solution are given, and it is shown that the build-up of the higher order Bennett-disequilibria through the cline is considerably more pronounced than the build-up of two-locus disequilibria.
19 citations
TL;DR: It is unequivocally demonstrate that in the nonheterocystous cyanobacterium, unlike in the heterocyStous strains, no gene rearrangement, either within thenif KDII cluster or in its vicinity, accompanies the expression of nitrogenase activity.
Abstract: The organisation of the structural genes for nitrogen fixation (nif K,D and H) in a nonheterocystous, filamentous cyanobacteriumPlectonema boryanum has been examined in comparison with a heterocystous cyanobacterium,Anabaena torulosa. DNA from repressed (fix-) cultures ofA. torulosa showed a discontinuousnif region spread over approximately 18 kb, an arrangement typical of the vegetative cells of heterocystous cyanobacteria. The region contained a contiguousnif DH separated fromnif K. by nearly 11 kb DNA. The intervening 11 kb DNA harboured the genexis A involved in the rearrangement ofnif K,D,H to form a cluster during differentiation of heterocysts. DNA fromPlectonema boryanum had a small, contiguousnif KDH cluster spanning a region of approximately 4 kb. DNA homologous to the 11 kb excison with its residentxis A was not present.Nif hybridisation patterns of restriction digests of the DNA isolated from repressed (fix-) or induced (fix--) cultures ofP. boryanum were completely identical. These results unequivocally demonstrate that in the nonheterocystous cyanobacterium, unlike in the heterocystous strains, no gene rearrangement, either within thenif KDII cluster or in its vicinity, accompanies the expression of nitrogenase activity.
17 citations
TL;DR: A method of analysis is described in which a bias is removed in the estimates of the genetical components of the variation of maternal effects and sex-linkage in diallel-cross analyses.
Abstract: Maternal effects and sex-linkage give rise to differences between reciprocal crosses. In diallel-cross analyses, the presence of these effects will cause biases in the estimates of the genetical components of the variation. A method of analysis is described in which this bias is removed. Also, a worked example demonstrates the analysis for a case where males only are available.
16 citations
TL;DR: It is proposed here that kdp is controlled by one fraction of intracellular [K+], and that the size of this fraction is independent of the osmolarity of the culture medium.
Abstract: The intracellular concentration of K+in Escherichia coli is known to be determined by osmolarity of the growth medium, and it is believed that the expression of the potassium-transport operon, kdp, is controlled by the turgor pressure differential between the cytoplasm and the extracellular environment. Several lines of evidence, however, argue against a strict turgor-regulation model for kdp expression. Instead, it is proposed here that kdp is controlled by one fraction of intracellular [K+], and that the size of this fraction is independent of the osmolarity of the culture medium.
13 citations
TL;DR: A strain ofDrosophila simulans was studied 40 generations after the transposable P element had been introduced into the genome by means of transformation, and the sterility found in the transfected strain may not result directly from transpositional activity of the P element.
Abstract: A strain ofDrosophila simulans was studied 40 generations after the transposable P element had been introduced into the genome by means of transformation. The genome also contained arosy transposon consisting of the wildtype allele of therosy gene flanked by P element DNA. During the 40 generations of evolution the number of P elements had increased to the level of 8–15 and the number ofrosy transposons to the level of 4–12. Continued transpositional activity in the germ line of the strain was evidenced by deletions occurring in therosy transposon and, in two independent sublines, by the transposition of therosy transposon from the X chromosome to the autosomes. Although at 25°C gonadal development and fertility appeared normal in both sexes, at 29°C both sexes were sterile. The sterile females had morphologically normal ovaries, but the sterile males often had shrunken, dysmorphic testes containing few or no immature sperm bundles. However, the sterility found in the transfected strain may not result directly from transpositional activity of the P element. The characteristics of theD. simulans strain infected with the P element are discussed in the context of factors that influence hybrid dysgenesis inD. melanogaster.
11 citations
TL;DR: Genetic evidence suggests that the suppressor mutation might define a distinct genetic locus which has been named FitB, which is independent of the medium of growth unlike the previously described intragenic suppression which is manifested only in rich media.
Abstract: Temperature-sensitivity due to thefit A76 mutation is suppressed by a mutation in a locus mapping in between the Pps and FitA loci, at approximately 37.3 min on theE. coli circular genetic map. Genetic evidence suggests that the suppressor mutation might define a distinct genetic locus which has been named FitB. Suppression by thefit B mutation is independent of the medium of growth unlike the previously described intragenic suppression which is manifested only in rich media. Infit B/fit B’ merodiploids there is a drastic reduction of suppression efficiency in minimal medium. The possible mode of action of the FitA and FitB gene products in transcription control is discussed.
8 citations
TL;DR: A chimeric DNA construction having nopaline synthase promoter, coding sequences of neomycin phosphotransferase gene conferring resistance to antibiotic kanamycin and OCS polyadenylation sequences bracketed by T-DNA ends was transferred to tobacco.
Abstract: A chimeric DNA construction having nopaline synthase promoter, coding sequences of neomycin phosphotransferase gene conferring resistance to antibiotic kanamycin and OCS (octopine synthase) polyadenylation sequences bracketed by T-DNA ends was transferred to tobacco. Leaf discs were infected withA. tumefaciens containing disarmed, cointegrate plasmid pGV3850:: 1103 and allowed to form a callus in the presence of kanamycin. Shoots regenerated from infected leaf discs either through the callus or arising directly were further selected for their ability to root in kanamycin-containing media. Among the nine transgenic plants that were progeny tested, the transferred bacterial gene segregated as monohybrid ratio (3 KanR: 1 Kans) in seven. Segregation data of two plant progenies indicated the presence of two independent loci of KanR DNA insertion (15 KanR: 1 Kan
s
). Back-cross segregation data were consistent with the monohybrid or independent assortment of duplicate factors. Thus in the two cases, a minimum independent integration of two copies of T-DNA each with a KanR marker is inferred.
TL;DR: A recessive lethal mutation of Drosophila melanogaster which as heterozygote enhances the phenotype of several mutant combinations of the BX-C-complex is described here; it is called Enhancer of bithorax (E(bx)2).
Abstract: A recessive lethal mutation ofDrosophila melanogaster which as heterozygote enhances the phenotype of several mutant combinations of thebithorax-complex (BX-C) is described here; it is calledEnhancer of bithorax (E(bx)2). The linkage group and the map position of this mutation have been determined; it maps on the third chromosome at - 1.65 map units. It has been cytologically localised to the region 61A1-6. This locus is a possible candidate for positive control of BX-C.
TL;DR: It is concluded that the male-haploid sex determination can, through the control of sex ratios, play a significant role in the evolution of eusociality in hymenopteran insects.
Abstract: The potential role of sex ratio biassing in the evolution of worker behaviour in male-haploid hymenopteran insects is examined using a deterministic genetic model. The model is based on a bivoltine life cycle with annual colonies and it assumes five gene loci, each of them controlling a specific feature of the life cycle (particularly brood sex ratios). The hypothetical gene controlling worker behaviour is assumed to be expressed either in the mothers (parental manipulation models) or in the female offspring (offspring altruism models). The threshold of the worker efficiency required for the worker behaviour to evolve is 0.5 under parental manipulation and 1.0 under offspring altruism when the sex ratios are not skewed. Worker evolution by offspring altruism can evolve more easily if the first workers initially raise mainly female brood. With such a sex ratio bias, the threshold of worker efficiency allowing eusociality to evolve drops below 1.0, even close to 0.8. Worker evolution is also favoured by the elimination of males from the first of the two annually occurring offspring generations. It is concluded that the male-haploid sex determination can, through the control of sex ratios, play a significant role in the evolution of eusociality in hymenopteran insects.
TL;DR: GATA-rich Bkm-related DNA in the mouse Y chromosome is closely associated with the sex determining locus in the Sxr (sex reversed) mutation and its effects on sexual differentiation were determined.
Abstract: GATA-rich Bkm-related DNA in the mouse Y chromosome is closely associated with the sex determining locus in the Sxr (sex reversed) mutation (Singh L and Jones K W,Cell 28: 205–216, 1982). Bkm-related male-specific DNA was gel separated from male mouse DNA as a > 23 kb band afterHue III andBst NI digestions and microinjected into mouse zygotes to determine its effects on sexual differentiation. We observed that 1 out of 7 XX embryos and 3 out of 35 weaned female mice possessed a > 23 kb male-specific band, though the hybridization intensity was very low in comparison to the normal control male. Two presumptive male carriers of the injected Bkm DNA were identified by progeny tests. Various sporadic anomalies in sexual phenotypes were noted but no obvious connection was established between these and the injected Bkm-related DNA. No significant effects on sex ratio were found.
TL;DR: The most striking feature of G6PD Punjab is a remarkable alteration in its electrophoretic behaviour after dialysis.
Abstract: Erythrocyte samples from 101 individuals, originally from Punjab and living at the time of investigation in England, were screened for glucose-6-phosphate dehydrogenase (G6PD) variants by Beutler’s fluorescent spot test and standard cellulose acetate gel (Cellogel) electrophoresis. All but 2 of the 40 males in the study were found to be indistinguishable from normal G6PD B. One of the variants had 2% of the normal activity and resembled G6PD Mediterranean in electrophoretic behaviour. The other variant showed 52% of the normal activity and migrated slower than G6PD B in Cellogel with about half of the normal band intensity. A set of physicochemical characteristics of the variant determined by conventional methods distinguished it from the variants reported so far. It was designated as G6PD Punjab, and the corresponding allele asG6PD PUN. The most striking feature of G6PD Punjab is a remarkable alteration in its electrophoretic behaviour after dialysis.
TL;DR: Erythrocytes from healthy men were examined for the presence of complement (C3b) receptor using haemagglutination assay with human aggregated IgG (aggIgG) and guinea pig complement and three phenotypes of complement receptor (CR) were distinguished.
Abstract: Erythrocytes from healthy men were examined for the presence of complement (C3b) receptor using haemagglutination assay with human aggregated IgG (aggIgG) and guinea pig complement. The results were expressed as the intensity of haemagglutination that corresponded to the C3b receptor sites density as evidenced by radioimmunobinding results. Among normal men three phenotypes of complement receptor (CR) were distinguished: high (CRh/CRh) phenotype corresponding to strong agglutination, an intermediate (CRh/CRI) producing weak agglutination and low phenotype (CRI/CRI) that gave no agglutination. In a population of 517 normal men these three phenotypes occurred in 63.8, 30.6 and 5.6%, respectively. Frequencies of the genes responsible for high (CRh) and low (CRI) expression of erythrocyte C3b receptor were 0.791 and 0.209, respectively.
TL;DR: Analysis of meiotic chromosomes from hybrids betweenedes atropalpus and Ae has revealed that the two species are fixed for alternate arrangements of four inversions, which disruption of meiosis was sufficient to account for the partial sterility observed in interspecific hybrids.
Abstract: Analysis of meiotic chromosomes from hybrids betweenAedes atropalpus andAe. epactius has revealed that the two species are fixed for alternate arrangements of four inversions: a paracentric inversion of chromosome 1, two paracentric inversions of chromosome 2, and a pericentric inversion of chromosome 3. This chromosomal heterozygosity in the interspecific hybrids has resulted in extensive meiolic chromosomal asynapsis. Dicentric bridges, acentric fragments, and chromosomal breakage were also associated with the heterozygous inversions. This disruption of meiosis was sufficient to account for the partial sterility observed in interspecific hybrids. No chromosomal polymorphisms, aberrations, or reduction in fertility was observed in parental strains of intraspecific hybrids of the two species.
TL;DR: Various constructed ridge count phenotypes were studied in two endogamous populations from peninsular India, finding them to be highly heritable, with the summed ridge counts for fingers and toes, and total ridge count showing almost Complete determination by additive polygenes.
Abstract: Various constructed ridge count phenotypes were studied in two endogamous populations from peninsular India. Heritabilities were estimated for five summed pattern ridge count traits: fingers and toes together; palms and soles together; fingers and palms together (manus); toes and soles together (pes); and fingers, palms, toes and soles together, defined as the total ridge count in man. In general, these phenotypes were found to he highly heritable, with the summed ridge counts for fingers and toes, and total ridge count showing almost Complete determination by additive polygenes. Total manus and pes pattern counts are less heritable. Little or no uterine environmental effects were detected for any of these phenotypes.