Showing papers in "Journal of Genetics in 1986"

Aggression patterns in adaptation and speciation of subterranean mole rats

Abstract: The patterns and correlates of aggressionwithin andbetween actively speciating subterranean mole rats of theSpalax ehrenbergi superspecies in Israel were tested in an attempt to approach an evolutionary theory of aggression related to both adaptation and speciation. Laboratory experiments were conducted on 314 adult mole rats (188 males and 126 females) caught in nature, representing 12 populations and comprising four chromosomal species (2n = 52, 54, 58, 60). The present analysis concentrates on “total aggression” comprising four aggressive variables: attacks, bitings, head-ons and sniffing with open mouth, out of 23 recorded variables. The results indicate that (a) aggression is distributed as a multipeak, discontinuous phenotypic parameter, displaying polymorphism within all 12 populations and 4 species tested; (b) the level of aggression was higher in males than in females, in the breeding than in the nonbreeding season, and displayed clinal geographic variation in both sexes across the superspecies range, where “militancy” increased northwards; (c) aggression was significantly correlated with ecological, physiological, genetical and ethological factors. These results support an evolutionary theory of aggression related to the intertwined processes of adaptation and speciation.

Genetics of amylose content in rice (Oryza sativa L.)

Abstract: Inheritance of amylose content was studied in crosses involving very low-, intermediate-, and high-amylose parents. The single-grain analysis of parents, F1, F2, B1F1, and B2F1 seed from a single-season harvest, showed that the parental mean difference of 14–17 % in IR37307-8/BPI 121-407 or IR37307-8/IR24632-34 and about 20% in the cross IR37307-8/IR8 were controlled by a single gene with major effect, along with some minor genes and/or modifiers. The appearance of segregants inbetween the two parents was attributed to gene dosage effects in the endosperm. The results indicate that selection for amylose level can effectively be done in early segregating generations. Selection for intermediary segregants would be ineffective because the dosage effects would dissipate in further generations.

Carboxyl-terminal mutants of phage Mu transposase

Abstract: A study of the properties of deletion mutants at the 3’ end ofA, the gene encoding the transposase protein of phage Mu, shows that the mutants are defective in the high-frequency non-replicative transposition observed early after Mu infection as well as the high-frequency replicative transposition observed during Mu lytic growth. They show near-normal levels of lysogenization, low frequency transposition and precise excision. The mutants behave as if they are “blind” to the presence of Mu B, a protein whose function is essential for the high frequency of both replicative and non-replicative Mudna transposition. We have sequenced these deletion mutants as well as the amber mutant A 7110 which is known to be defective in replicative transposition.A 7110 maps at the 3’ end of geneA. We suggest that the carboxyl-terminal region of the A-protein is involved in protein-protein interactions, especially with the B-protein. We also show in this study that mutations upstream of the Shine-Dalgarno sequence of geneA and within the preceding genener, perturb the synthesis of A-protein and that higher levels of A-protein cause an inhibition ofA activity.

Evidence for multiple mating in the primitively eusocial wasp Ropalidia marginata (Lep.) (Hymenoptera: Vespidae)

Abstract: Assymetries in genetic relatedness ceated by haplodiploidy have been considered to be crucially important for the evolution of worker behaviour in Hymenoptera. Multiple mating by the queens destroys this assymetry and should make kin selection less powerful. The number of males that social insect queens mate with is thus of considerable theoretical interest especially in prmitively eusocial species. The results presented here provide evidence for multiple mating by foundresses of the primitively eusocial wasp Ropalidia Marginata (Lep.).

Determining the order of genes, centromeres, and rearrangement breakpoints inNeurospora by tests of duplication coverage

Abstract: Nontandem segmental duplications provide a useful alternative to conventional recombination mapping for determining gene order in a haploid organism such asNeurospora. When an insertional or terminal rearrangement is crossed by Normal sequence, a class of progeny is produced that have a precisely delimited chromosome segment duplicated. In such Duplication progeny, a recessive gene in the Normal-sequence donor chromosome may or may not be masked (“covered”) by its dominant wild-type allele in the translocation-sequence recipient chromosome. Coverage depends upon whether the gene in question is left or right of the rearrangement breakpoint. The recessive gene will be heterozygous and covered (not expressed) if its locus is within the duplicated segment, but it will be haploid and expressed if the locus is outside the segment. Not only genes but also centromeres can be mapped by means of duplications, because genes included in. the same viable duplication must reside in the same chromosome arm. - Numerous sequences in the current genetic maps ofN. crassa have been determined using duplications. Gene order in the albino region and in the centromere region of linkage group I provide examples. Over 50 insertional or terminal rearrangements are available from which nontandem duplications of defined content can be obtained at will; collectively these cover about 75% of the genome. - Intercrosses between partially overlapping chromosome rearrangements also produce Duplication progeny containing two copies of regions between the breakpoints. The 180 mapped reciprocal translocations and inversions include numerous overlapping combinations that can be used for duplication mapping.

Genetic analysis of bacterial plasmid promiscuity

Abstract: The genetic basis of the promiscuous behaviour of bacterial plasmids has been investigated by study of the incompatibility P-1 group of conjugative plasmids of gram-negative bacteria. Both transposon mutagenesis and the construction of minireplicons linking varying combinations of the plasmid genome have shown that specific genomic regions control the conjugational transfer and vegetative replication of the plasmid in specific bacterial hosts. These include the plasmid DNA primase gene, the origin of plasmid transfer, a region near the origin of transfer, the origin of plasmid vegetative replication, thetrans- acting gene essential for the initiation of plasmid replication and a region involved in its regulation. DNA sequence analysis has identified the requirement of specific direct repeats within the origin of replication for plasmid replication in some but not in other hosts. The cloning of some of the trans-acting genes onto multicopy cloning vectors and complementation tests have shown that the requirements of these gene products vary in different hosts and that the plasmid has evolved genetic strategies for their optimal expression.

Environmental fluctuations: How do they affect the topography of the adaptive landscape?

Abstract: A Phenotypic Adaptive Landscape is defined with fitness as the ordinate, and longevity of the juvenile phase and duration of disturbances to the adult phase as the horizontal axes. The effect of local environmental perturbations on the landscape’s shape is studied using a semistochastic population model. In this model the intrinsic population dynamics takes the form of a differential-delay nonlinear equation and the environmental disturbance appears as a multiplicativetelegraphic noise. We demonstrate that the landscape has no single characteristic scale. Rather, it shows adaptive peaks corresponding to an integer relation between the biological and the environmental periodicities. Since the system is constrained by a finite time and a finite physiological range, the landscape may have different topographies for different local environmental regimes. A very simple fully deterministic model is presented, predicting landscapes that are similar to those obtained by the semistochastic model. Application to life history strategies are discussed.

Transformation ofBrassica juncea byAgrobacterium tumefaciens harbouring plasmid pTiT37 and its ‘rooty’ mutant pTiT37.14a/a

Abstract: Indian mustard (Brassica juncea Linn., Czern and Coss) plants were inoculated withAgrobacterium tumefaciens strain A208 harbouring either plasmid pTiT37 or pTiT37.14a/a. The latter carries an insertion at the ‘rooty’ locus (gene 4 orcyt) of the T-DNA governing cytokinin biosynthesis. The tumours induced by pTiT37.14a/a were small and formed many roots. Forin vitro culture, these transformed cells required supplementation of the basal medium with IAA and kinetin in the initial stages though after six sub-cultures they were also hormone autotrophic.In vitro cultures showed profuse rooting like the inplanta tumours. Unlike transformed tobacco and carrot cells,Brassica juncea cells transformed by pTiT37.14a/a could not be induced to differentiate into shoots. In contrast, the cells transformed by the wild type pTiT37 were hormone autotrophic and occasionally differentiated into shoots but could not be induced to produce roots. These results demonstrate how a single gene mutation affecting cytokinin biosynthesis can alter the inplanta as well as thein vitro response of a transformed cell of the same genotype.

Expression in E. coli of the cloned cDNA for the major antigen of foot and mouth disease virus Asia 1 63/72

Abstract: Double stranded cDNA for the foot and mouth disease virus was prepared, restricted with BamH 1 or ligated to linkers with BamH 1 sticky ends and cloned in BamHI site in the expression vector,pUR222. The cDNA was also cloned at the Pst l site in the same vector by the dC/dG tailing method. They were transferred into E. coli to give colourless colonies in the presence of the dye, X-gal. Many of them showed positive signal on hybridization with $^{32}P$-labelled viral RNA. The middle BomH 1 fragment of the cDNA is known to carry the gene for the major antigen and some non-structural proteins. The clones carrying the recombinant DNA produced proteins which cross-reacted with the antibodies generated against the structural proteins of the virus in an enzyme linked immunosorbent assay, indicating that the cDNA of the major antigen is expressed in the cloned cell.

Foundations of genetic epidemiology

Abstract: The history of epidemiology has been its generalization of the word \"epidemic\" from explosive outbreak of an infectious disease to any nonrandom cluster of events in space, time, or subpopulation. The latest stage in that progress was reached when public health measures had reduced the impact of infectious disease in industrial societies and emphasis shifted to chronic disease. Synthesis of goals .and methods from epidemiology and genetics became desirable and inevitable. Thus, genetic epidemiology was born, a science that deals with etiology, distribution, and control of disease in groups of relatives and with inherited causes of disease in populations. The set of relatives may be as close as twins or as extended as an ethnic group. Inherited, as used here in a broad sense, includes both biological and cultural inheritance. Genetic epide.miology is also derived from population genetics, which originally subsumed all mathematical properties of genetic transmission in families and populations. The beginning of fission may be traced to C C Li's Introduction to Population Genetics. Whereas the first (1948) edition began with a chapter on segregation analysis, this was omitted in the 1955 edition with the comment that \"the nature of the subject is not quite the same as that of the rest of this book.\" In the interval Neel and Schull (1954) were apparently the first to recognize a new discipline of \"epidemiological genetics\" dealing with contemporary, health-related problems. Later, the term \"genetic epidemiology\" was preferred because determinants of familial aggregation are partly environmental, and one task of genetic epidemiology is to separate these rigorously from genetic factors. The terms \"biometrical genetics\" and \"quantitative genetics\" fall increasingly into disuse because they omit major loci, chromosomal aberrations, and cultural inheritance. Evolutionary genetics, the major branch of population genetics, has been diminished by separation of theoretical and observational branches, of which domination of macroevolutionary research by paleontology is one example, and emergence of genetic epidemiology is another. Major population geneticists have emphasized interplay between lnathematical formulation and empirical tests of hypotheses, and thereby subsuined evolutionary genetics and what has come to be

Evolution of sex ratios in social hymenoptera: Consequences of finite brood size

Abstract: Evolutionarily stable sex ratios are determined for social hymenoptera under local mate competition (LMC) and when the brood size is finite. LMC is modelled by the parameterd. Of the reproductive progeny from a single foundress nest, a fractiond disperses (outbreeding), while (l-d) mate amongst themselves (sibmating). When the brood size is finite,d is taken to be the probability of an offspring dispersing, and similarly,r, the proportion of male offspring, the probability of a haploid egg being laid. Under the joint influence of these two stochastic processes, there is a nonzero probability that some females remain unmated in the nest. As a result, the optimal proportion of males (corresponding to the evolutionarily stable strategy, ESS) is higher than that obtained when the brood size is infinite. When the queen controls the sex ratio, the ESS becomes more female biased under increased inbreeding (lowerd). However, the ESS under worker control shows an unexpected pattern, including anincrease in the proportion ofmales withincreased inbreeding. This effect is traced to the complex interaction between inbreeding and local mate competition.

Genetic differentiation in theAedes atropalpus complex. I. Isozyme variability and genetic distances betweenAe. atropalpus andAe. epactius

Abstract: During the course of their evolution,Ae. atropalpus andAe. epactius have undergone considerable genetic differentiation. The average genetic distance between the two species was 0.458 ±0.05. The average genetic distance between populations ofAe. atropalpus was 0.019 ± 0.01 while the average distance between populations ofAe. epactius was 0.075 ±0.02. The GREEN population, representing the new “form” ofatropalpus found breeding in discarded tires, exhibited electromorph frequencies characteristic of the “typical”atropalpus populations. Of the enzymatic loci examined, ADK2 was species diagnostic, and PGi was species discriminating. The electrophoretic results from the populations examined have provided additional support for the present taxonomic status of the two species.

Evaluation of genetic radiation hazards in man: History, present status and perspectives

Abstract: The evaluation of genetic radiation hazards in man is an ongoing scientific enterprise from about the mid-1950s. Since estimates of genetic risks are essential for providing a basis for protecting our genetical endowment and since strictly relevant human data are limited, there is no alternative at present but to use the data from mouse and certain non-human primates. This paper reviews the general principles and methods that have thus far been used, appraises the evolution of the conceptual framework, the data base and the assumptions involved, presents current estimates of genetic risks and provides some perspective of the advances that are likely to be made in the near future.

Genetics of meprin in the rat

Abstract: The locus encoding for meprin activity in kidney was found polymorphic in the rat. The BDIV and COP strains that carried theMep-1a allele had high meprin concentration in the kidney, while the ACI, BN, LE and LEW strains that carried theMep-1b allele had low meprin levels. TheMep-1a allele that controlled the high activity enzyme was expressed in a dominant fashion in the (BN × COP) F1 progeny. The backcross studies showed that the segregation of alleles at theMep-1 and theGlo-1 loci was normal and that the genes were linked (x2 = 4.06,P < 0.05). The map distance between theMep-1 andGlo-1 genes was 41 ± 4 centimorgans.

Homospecific and heterospecific transformation with chimeric plasmid DNA inHaemophilus influenzae andHaemophilus parainfluenzae

Abstract: A gene for resistance to novobiocin has been self-cloned inH. parainfluenzae, using a high-efficiency plasmid vector pJ1-8: Homospecific and heterospecific transformation using chimeric plasmids containing an insert of thenovr gene ofH. influenzae orH. parainfluenzae has revealed some novel features. There is some evidence from our observations thatH. parainfluenzae also recognises specific uptake sites in the incoming DNA. Transformation with chimeric and non-chimeric plasmids suggests that the homology of the insert to the resident DNA has a major role in the extrachromosomal fixation of chimeric plasmids. It is also inferred that apart from the (passive) internalisation of input DNA from transformasomes, there is also recombination-assisted internalisation.

Linkage ofaconitase-1 andmajor urinary protein-1 loci in male rats

Abstract: A new major urinary protein alleleMup-lc with “null” activity was detected in males of the COP strain. The (BN X COP)F1 X COP backcross had significant segregation distortion of theMup-lc andAco-1 alleles that indicated a linkage between the genes, at a map distance of 13 ± 4 cM. The loci reside on the linkage group II of the rat with theb locus. According to our data and the results published previously, the map distance and the orientation of genes isb - 8 ± 4 -Mup-1 - 13 ±4-Aco-1. These genes form a syntenic group in both the mouse and the rat.

Esterase-6 polymorphism inDrosophila melanogaster:Effects of temperature and methyl malonate on genotypic trajectories in polymorphic populations set up with highly inbred lines

Abstract: It is generally difficult to identify possible effects of selection at a specific locus because of the heterogeneity of the genetic background. Geographical patterns ofEst-6 gene frequencies suggest that there is selection at this locus but selection on loci closely linked to it cannot be excluded. Differences in catalytic properties between allozymes have been shownin vitro; further, several laboratory studies have shown apparent fitness differences between allozymes. Our study used inbred lines highly homogeneous in the genetic background. Four populations were set up fromEst-6s andEst-6F homozygous females inseminated by males of the same genotype at each combination of three factors: temperature (18 and 25°C); methyl malonate (presence or absence); input gene frequencies [p(S) = 0.2 and 0.8]. The populations were sampled periodically for about 28 generations. Methyl malonate was chosen to exert pressure in the enzymatic function of esterase-6. Statistical analyses show that: there are no sex differences; gene frequencies change from input values to those of the first sampling, when only individuals of the first generation are present at 18oC or individuals of the second generation just begin to appear at 25°C; gene frequencies do not change thereafter and Hardy-Weinberg equilibrium is established. The changes in gene frequencies observed in the first generations suggest thatEst-6 can under certain conditions be a target of selection. Such conditions may not, however, occur in natural populations.