bluuebunny/crossref_metadata_2025_split huggingface dataset:
Recombination and the evolution of satellite DNA
Authors: Stephan Wolfgang 
Published: September 2009

SummaryIn eukaryotic chromosomes, large blocks of satellite DNA are associated with regions of reduced meiotic recombination. No function of highly repeated, tandemly arranged DNA sequences has been identified so far at the cellular level, though the structural properties of satellite DNA are relatively well known. In studying the joint action of meiotic recombination, genetic drift and natural selection on the copy number of a family of highly repeated DNA (HRDNA), this paper looks at the structure–function debate for satellite DNA from the standpoint of molecular population genetics. It is shown that (i) HRDNA accumulates most probably in regions of near zero crossing over (heterochromatin), and that (ii), due to random genetic drift the effect of unequal crossover on copy numbers is stronger, the smaller the population size. As a consequence, highly repeated sequences are likely to persist longest (over evolutionary times) in small populations. The results are based on a fairly general class of models of unequal crossing over and natural selection which have been treated both analytically and by computer simulation.
Induction of new mutations in a mouset-haplotype using ethylnitrosourea mutagenesis
Authors: Justice Monica J. , Bode Vernon C. 
Published: September 2009

SummaryN-ethyl-N-nitrosourea (ENU) was used to induce mutations within thetw5-haplotype of the mouse to make possible a further study of gene arrangement int-mutants and to provide potential landmarks for cloning and sequence studies in the region. Two independent mutants were isolated for each of three loci in thet-region, brachyury (T), quaking (qk), and tufted (tf). The newTktalleles produce tailless mice when atctmutation is present intrans. The newqkktalleles are recessive and homozygous lethal. They are viable, male fertile, and cause seizures and quaking when paired with theqkmutation which previously defined the locus. Thetfktmutations are recessive and phenotypically similar to the mutant alleles available in non-tchromosomes. The mutations were induced in thetw5-haplotype at an average per locus frequency of 1 in 1500. Their isolation demonstrates the power of this technique for obtaining the specific mouse mutants that are needed to genetically dissect a complex mammalian system.
Selection for growth on normal and reduced protein diets in mice: I. Direct and correlated responses for growth
Authors: Nielsen B. Vivi Hunnicke , Andersen Søren 
Published: September 2009

SummaryMice were selected for growth from 3 to 9 weeks of age on a normal protein diet (N) containing 19·3% protein and a reduced protein diet (R) containing 5·1% protein. On each diet there were 3 high (H), 3 low (L) and 3 unselected control (C) lines. After 6 generations of selection, half of the mice in each line were tested on each diet. Responses were obtained when selecting for both increased and decreased growth on both diets. The realized heritabilities from within-family selection were 33 and 26% for the divergences on the normal and reduced protein diets, respectively. Consistent genotype-environment interactions were found when all lines were tested on both diets in generation 7. Performance on each protein level was best improved by selection on that protein level. Further, the correlated response was significantly less than the direct response when selecting on both diets. The estimates of the genetic correlation between growth on the two protein levels were low,rN= 0·16 from selection on the normal protein diet andrR= 0·51 from selection on the reduced protein diet. Selection resulted in a change in environmental sensitivity in the lines, dependent on the diet and direction of selection. The average of the divergences on the two diets was not dependent on the selection environment.
Heterogeneity of human haptoglobin α chains detected by two-dimensional gel electrophoresis
Authors: John Huw A. , Purdom Ian F. 
Published: September 2009

SummaryThe protein spots representing the haptoglobin α1F, α1Sand α2chains in two-dimensional gels of human plasma samples representative of the six common haptoglobin phenotypes were identified by comparing their position with those of purified haptoglobin and distinguished from other spots in the vicinity by comparison with plasma with undetectably low levels of haptoglobin. Silver staining indicated that the α1Fchain was represented by one spot in subtypes 1F-1F, 1F-1S and 1F-2, the α1Schain by three spots in subtypes 1S-1S, 1F-1S and 1S-2 and the α2chain by six spots in 1F-2, 1S-2 and 2–2
Non-random inactivation of theX-chromosome in interspecific hybrid voles
Authors: Zakian S. M. , Kulbakina N. A. , Meyer M. N. , Semenova L. A. , Bochkarev M. N. , Radjabli S. I. , Serov O. L. 
Published: September 2009

SummaryExpression ofX-linked genes for G6PD and GALA in interspecific hybrids betweenMicrotus arvalis, M. subarvalisandM. kirgisorumvoles was studied. Quantitative predominance of the enzyme activities ofM. arvalisover G6PD activity ofM. subarvalisand the GALA activity ofM. kirgisorumin the female hybrids was shown. The definitive patterns of these enzyme activities was found on day 6·5 of embryonic development. Non-random inactivation ofX-chromosomes derived fromM. subarvalisandM. kirgisorumin the interspecific hybrids withM. arvalisis supposed to be the cause of the phenomenon observed. A hypothesis is proposed that there is a connection between the presence of large heterochromatin regions in theX-chromosomes derived fromM. subarvalisorM. kirgisorumand the preferential inactivation of these in female hybrids withM. arvalis.
Additive variance and average effect with partial selfing
Authors: Wright A. J. 
Published: September 2009

SummaryThe covariance of an ancestor and the average of its descendants in generationt(CPt)is formulated for a breeding system which is a mixture of selfing and outcrossing. This covariance is partitioned into least squares additive (σA. At) and non-additive (σD. Dt) components summed over individual loci, and the combined inbreeding effects of all loci (H′), such thatCPt= σA. At+ (s/2)t[σD. Do+H′]. For themth locus the covariancemσA. At= 2(1 +F)Σipiα(0)iα(t)i, in whichpiis the frequency of theith allele whose additive effect (α(t)) depends on the generation for which it is defined. For distant descendants α(∞)is equal to half of the derivative of the population mean with respect to the frequency of the allele. The covarianceCP∞= σA. A∞thus relates directly to permanent selection response measured in the equilibrium population, any additional responses observed in earlier generations being due to temporary disturbances in population genotypic structure. It is only for these distant descendants that the least squares additive component has any direct interpretation in terms of selection response. The definitions of α(0)and α(∞), lead to two distinct definitions of the average effect of an allele substitution for a model with two alleles (Fisher, 1941), and to a clarification of their significance for this breeding system.
Y-chromosomal DNA polymorphism in mouse inbred strains
Authors: Nishioka Yutaka 
Published: September 2009

SummaryMice are the most widely used experimental mammals, and many inbred strains are available. However, except for the relatively recent strains derived from known wild populations, the relationships between wild and laboratory mice are not well understood. Based on the Y-chromosomal restriction fragmentlength polymorphism, seventeen inbred strains were classified into two groups: strains with theMus musculus musculustype Y chromosome and those with theM. m. domesticustype Y chromosome. We extended the survey to an additional twenty-two inbred strains. TheM. m. musculustype Y chromosome was found in AEJ/GnLe, AAU/SsJ, BDP/J, BXSB/MpJ, DA/HuSn, HTG/GoSfSn, I/LnJ, LP/J, NZW/LacJ, RIIIS/J, SB/Le, SEA/GnJ, SF/CamEi, SK/CamEi, SM/J, WB/ReJ, WC/ReJ and YBR/Ei, while theM. m. domesticustype Y chromosome was present in BUB/BnJ, MA/MyJ, PL/J and ST/bJ.
Temporal stability of P–M cytotype polymorphism in a natural population ofDrosophila melanogaster
Authors: Izaabel Hassan , Ronsseray Stephane , Anxolabéhère Dominique 
Published: September 2009

SummaryThe P–M system of hybrid dysgenesis inDrosophila melanogasteris a syndrome of genetic abnormalities which appears in the progeny of crosses between strains different with regard to their possession of ‘P’ transposable elements. Cytotype is an extrachromosomal property which regulates the mobility of the P element. We report here data showing that a cytotype polymorphism previously observed in a natural population from North-Africa is stable over a period of 5 years. A potentially high rate of mutation is associated with this cytotype polymorphism. Explanations of the appearance of a cytotype polymorphism are proposed and the consequences for the genetic load induced by transposable elements are discussed.
Hybrid dysgenesis in natural populations ofDrosophila melanogasterin Japan. II. Strains which cannot induceP-Mdysgenesis may completely suppress functionalPelement activity
Authors: Hagiwara Nobuko , Nakamura Etsuko , Matsuura Etsuko T. , Chigusa Sadao I. 
Published: September 2009

SummaryMany inbred and isofemale lines derived from wild populations ofDrosophila melanogasterwere tested for gonadal dysgenic sterility, male recombination andsnwsecondary mutation. Among them, we have found strains whose dysgenic offspring show negligible sterility, and undetectable male recombination andsnwmutation. They can be considered to be neutral strains in the strict sense. Such neutral strains appear to carry only defectivePelements in their genomes. Taking the observations of Karess & Rubin (1984) into account, it is suggested that some defectivePelements retain the function necessary forPcytotype. Cytotype determination mechanisms are discussed.
Nucleotide sequence analysis of class II genes borne by mousetchromosomes
Authors: Golubić M. , Budimir O. , Schoepfer R. , Kasahara M. , Mayer W. E. , Figueroa F. , Klein J. 
Published: September 2009

SummaryFive class IIH-2genes borne bytchromosomes were partially sequenced:borne by thetTuw10chromosome of EDY589 (H-2w2);andborne by thetTuw8chromosome of CR0437 (H-2w57), as well asandborne by thetTuw7chromosome of CR0435 (H-2w37). These genes are representatives of the three major groups of alleles found associated withtchromosomes. The sequenced part consisted of almost the entire exon 2 and the entire exon 3 coding for the first and the second domain of the β polypeptide chains, respectively. The sequence was compared with the published sequences ofAβandEβalleles borne, by non-tchromosomes. The comparison revealed that thet-associated alleles are no more similar to one another than they are to the corresponding genes present on non-tchromosomes in laboratory mice. This divergence in the nucleotide sequence among the class II genes is interpreted as evidence that thetcomplex is very old.
Genetic effects on susceptibility to histidine induced teratogenesis in the mouse
Authors: Burns Julie E. , Kacser Henrik 
Published: September 2009

SummaryIn the mouse histidinaemia has a teratogenic effect. Animals subjected to high levels of histidine in utero may develop inner ear and behavioural abnormalities typical of the ‘shaker–waltzer’ syndrome. Selection procedures for abnormalities and relaxation of selection have resulted in two histidinaemic strains: the Cambridge strain in which abnormalities occur in over 80% of animals, and the Edinburgh strain in which the penetrance of abnormal behaviour has declined to about 1%. Breeding experiments suggest that the differences are largely due to differences in the genetic backgrounds which modify foetal susceptibilities to the teratogenic effects of high histidine levels. High susceptibility appears to be dominant over low susceptibility in the present strains. There appears to be no interaction of maternal histidinaemia with the dreher mutation which is considered to induce inner ear malformation as a result of an early neural tube abnormality.
Estimating the proportion of neutral mutants
Authors: Watterson G. A. 
Published: September 2009

SummaryKimura used the heterozygosity and the number of low-frequency alleles to estimate that about 14% of mutations are selectively neutral. The method is shown to be subject to biases and to disruption due to bottleneck effects. Let deleterious alleles have selective disadvantage,s, compared with neutral alleles and letNedenote the effective diploid population size. The estimator,, of the proportion of neutral alleles is positively biased if (roughly) 4NeS< 25 or if 4Nes> 200. In the former case, one cannot adequately detect the different influences of deleterious and neutral alleles, whereas in the latter case, deleterious alleles will rarely appear in the sample. These difficulties cause the biases in, and are likely to cause similar biases for any estimation method based solely on allele frequencies. There is substantial sampling variability inin cases of practical interest, when data from 11 loci, or even as many as 31 loci, are pooled. If there has been a recent contraction in population size,will be positively biased, often yielding values greater than 1 or even being infinite. But after a recent expansion in population size, the heterozygosity will not have made as quick an increase andwill be negatively biased. Population expansion alone can producevalues close to those observed by Kimura, even if all alleles are neutral. In an appendix, a new method for simulating samples of neutral and deleterious genes is described.
Erratum
Authors: Caddick Mark X. , Arst Herbert N. 
Published: September 2009

Genet. Res., Camb. (1986), 47, pp. 83–91Structural Genes for Phosphatases in Aspergillus nidulansA labelling error caused nimD-4 to be substituted for nimQ-20. The nim locus shown in Fig. 3 (p. 88) is nimQ not nimD. The genotypes of strains given in the legend to Fig. 3 should read nimQ-20 in place of nimD-4.
The organization and composition of the ribosomal RNA gene non-transcribed spacer ofD. busckiiis unique among the drosophilids
Authors: Slavicek James M. , Krider Hallie M. 
Published: September 2009

SummarySeveral ribosomal RNA (rRNA) genes fromD. busckiiwere cloned and characterized. The prominent repeat classes have lengths of 12·8 and 13·6 kb and lack 28S introns. rRNA genes were cloned containing 28S insertions which exhibit heterogeneity in size and sequence. The non-transcribed spacer (NTS) contains two regions composed of different repeated sequences that exhibit pronounced instability in HB 101. NTS region II, centrally located within the NTS, contains predominately 11 or 16HincII generated 160 bp repeats. NTS region III, next to the 18S gene, contains repeats that are variable in number, and are either heterogeneous in length or are dispersed within unique sequences. The organization and composition of the rRNA gene NTS ofD. busckiiis different in comparison to the NTSs of other drosophilids. In addition, the pronounced instability of two different NTS regions is unique in comparison to all other cloned rRNA genes.
A new allele of the testosterone-responsive gene,Hdc-a, in the histidine decarboxylase gene complex of the mouse
Authors: Middleton Richard J. , Williamson Kathleen , Bulfield Grahame 
Published: September 2009

SummaryIn C57BL/10 and the majority of other strains of mice, females have about 20-fold higher kidney histidine decarboxylase levels than males; in DBA/2 mice, however, HDC in females is only 3- to 4-fold higher than males. The low ratio HDC phenotype of DBA/2 animals is due to decreased sensitivity of the HDC gene complex to repression by testosterone in males. From conventional crosses and by the use of the BXD recombinant inbred lines we conclude that the C57BL/ 10: DBA/2 difference, in testosterone sensitivity of HDC, is due to an allelic difference in the regulatory geneHdc-aof the HDC gene complex, [Hdc], on chromosome 2; DBA/2 contains a third allele of this gene,Hdc-ad.
Molecular characterization of a radiation-induced reverse mutation at the dilute locus in the mouse
Authors: Favor Jack , Strauss P. Günter , Erfle Volker 
Published: September 2009

SummaryIrradiation has been employed successfully to increase the reverse mutation rate at the agouti and dilute loci in the mouse. The dilute allele has previously been shown to be due to the insertion of an ecotropic-specific murine leukaemia virus in the vicinity of the dilute locus, and its instability to be due to the excision of the proviral sequence (Jenkinset al.1981). Molecular analysis of the recovered radiation-induced revertant at the dilute locus indicated excision of all but approximately 500 bp of the proviral sequence. The proviral sequence remaining in the mouse genome hybridizes to a probe specific for the proviral long terminal repeat (LTR) sequence. Previous characterization of two spontaneous reverse dilute mutations indicated precise proviral excision of all but a single LTR, and suggests homologous recombination between the proviral LTR sequences as the mechanism of proviral excision (Hutchison, Copeland & Jenkins 1984). The present results indicate that radiation and increases the reverse mutation rate at the dilute locus acts by a similar mechanism, and suggest that mutagenic treatment may be employed to produce genetic variants of interest.
Errata
Authors: John Huw A. , Purdom Ian F. , Wright A. J. 
Published: September 2009

Genet. Res., Camb. (1987), 50, pp. 17–21Heterogeneity of human haptoglobin α chains detected by two-dimensional gel electrophoresisThe running title for this article should have been Human plasma haptoglobin α chain heterogeneityGenet. Res., Camb. (1987), 50, pp. 63–68Additive variance and average effect with partial selfing(1) The second line of Table 1 should read
Characterization and mapping of a viable anaemic mutant in the mouse: a new allele,mkvan, at themicrocytic anaemialocus
Authors: Handa Sunil , Ferguson Janet M. , Wallace Margaret E. , Bulfield Grahame 
Published: September 2009

SummaryA viable anaemic mouse mutant arose in the stock of a mouse fancier and has been characterized haematologically and genetically. Anaemic animals were less viable than normal animals (especially from 0 to 2 weeks of age) and had lower haemoglobin levels, percentage packed-cell volumes, higher red cell counts and lower mean cell volume than normal animals. Peripheral blood films showed a wide range of abnormal cells and extreme microcytosis. Linkage studies showed the mutant to be linked to the chromosome 15 markersNa Caandbt; recombination withCawas 1·37 ± 0·68 % for females and 10·5 ± 7·41 % for males. This position is similar to themicrocytic anaemia, mk, mutant, and crosses between the viable anaemia mutation andmk/mkhomozygotes showed the two to be allelic. Viable anaemia is therefore a second allele at themklocusmkvan; new data give its position on chromosome 15.
Variance components of fitness under stabilizing selection
Authors: Tachida Hidenori , Cockerham C. Clark 
Published: September 2009

SummaryVariance components of fitness under the stabilizing selection scheme of Wright (1935) for metric characters are calculated, extending his original analysis to the case with any number of alleles and multiple characters assuming additivity of gene effects. They are calculated in terms of the moments of the effects of alleles at individual loci for the metric characters. From these formulas, the variance components of fitness are evaluated at the mutation–selection equilibria predicted by the ‘Gaussian’ approximation (Lande, 1976), which is applicable if the per locus mutation rate is high, and the ‘House of Cards’ approximation (Turelli, 1984), which is applicable if the per locus mutation rate is low. It is found that the additive variance of fitness is small compared to non-additive variance in the ‘Gaussian’ case, whereas the additive variance is larger than non-additive variance in the ‘House of Cards’ case if the number of loci per character and the number of characters affected by each locus are not too large. With the assumption that a significant portion of fitness is due to this type of stabilizing selection, it is suggested that the real parameters are in the range where the ‘House of Cards’ approximation is applicable, since available data on variance components of fitness components in Drosophila show that the additive variance is far larger than the non-additive variance. It is noted that the present method does not discriminate the two approximations if the average values of the metric characters deviate from the optimum values. Other limitations of the present method are also discussed.
The inheritance of non-response to noradrenaline in newborn Scottish Blackface lambs
Authors: Simpson S. P. , Slee J. 
Published: September 2009

SummaryThe normal response to injection of noradrenaline (NA) in newborn lambs is an increase in metabolic rate and rectal temperature, due to the stimulation of non-shivering thermogenesis. In a previous study 6 out of 7 lambs born to a sire previously selected for low resistance to cold failed to show this characteristic response and were termed non-responders. The sire, 2 of his male offspring and 6 sires selected randomly from the flock were mated to several ewes and the response to NA stimulation recorded in 116 newborn lambs. Control sires produced only normal responder lambs whereas the remaining sires all produced both responder and non-responder lambs. The proportion of non-responders was not significantly different from 0·50, which is consistent with a dominant major gene. Analysis of the quantitative traits, peak metabolic rate and peak rectal temperature following NA injection confirms that a major gene is segregating in the study population, but is unable to distinguish between dominant and recessive modes of inheritance. Absence of non-responders in other studies suggests that dominance is more likely. This new genetic resource could aid our understanding of brown adipose tissue metabolism and the effect of catecholamines on metabolic pathways.
A vector for studying plasmid stability functions in Streptomyces
Authors: Kendall Kevin , Cullum John 
Published: September 2009

SummaryWe constructed a cloning vector (pMT603) based on the low copy number plasmid SCP2*. pMT6O3 is unstable because it lacks the SCP2* stability region and carries the selectable marker thiostrepton-resistance and a tyrosinase gene which results in melanin production. This allows easy testing of plasmid stability and we demonstrated its usefulness by cloning a plasmid stability function.
Evidence that mitochondrial isozymes are genetically less variable than cytoplasmic isozymes
Authors: Ward Robert D. , Skibinski David O. F. 
Published: September 2009

SummaryIt has been proposed that isoenzymes functioning within cell organelles (chloroplasts, mitochondria) are genetically less variable than their cytoplasmic counterparts, as a result either of constraints imposed by the need to cross organelle membranes or from the different and specialized nature of organelle metabolism. However, some recent findings concerning chloroplast and cytoplasmic isozyme variability are not consistent with this thesis. We have analyzed a number of surveys of electrophoretically detectable enzyme variation in vertebrates, and show that for each of the four tested enzymes (malate dehydrogenase, isocitrate dehydrogenase, malic enzyme, and aspartate aminotransferase), the mitochondrial isozymes are less variable than their corresponding cytosplasmic forms. The mean heterozygosities across the four enzymes are 0·083 and 0·038 for the cytoplasmic and mitochondrial forms respectively. We conclude that mitochondrial isozymes are indeed subject to greater constraints than cytoplasmic forms and have fewer sites able to accept neutral or slightly deleterious mutations. It is also noted that of the enzymes analyzed, that with the smallest subunit molecular weight (MDH) has the least variable cytoplasmic and mitochondrial isozymes, whereas the enzyme with the largest subunits (ME) has the most variable isozymes.