Towards a methodology of teleonomy.
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Data on reproductive performance of the White Fulani (Bunaji) cattle in Southern Nigeria were analysed. Age at first calving, first and overall calving intervals averaged 4.03 +/- 0.43 years, 436.19 +/- 9.32 and 420.98 +/- 4.11 days respectively. The year of birth significantly affected age at first calving and calving interval (P less than 0.01) but the season of birth had significant effect only on calving interval (P less than 0.05). In addition the age of the dam also affected the calving interval (P less than 0.05) but the sex of the calf nursed had no effect. Heritability estimates from half-sib analysis were 0.01 +/- 0.03, 0.26 +/- 0.10 and 0.28 +/- 0.08 respectively for age at first calving, first and overall calving intervals. Low repeatability estimates were obtained for calving intervals.
The biological processes leading to sex expression in plants are of tremendous practical significance for fruit production of many agricultural and horticultural crops. Sex-expression studies in cucumber showed that the different sex types are determined by three major genes: M/m, F/f and A/a. The M/m gene in the dominant condition suppresses stamina development and thus leads to female flowers. The F/f gene in the dominant condition shifts the monoecious sex pattern downwards and promotes femaleness by causing a higher level of ethylene in the plant. To investigate the molecular character of the gene F/f, we used nearly isogenic gynoecious ( MMFF) and monoecious ( MMff) lines (NIL) produced by our own backcross programme. Our investigations confirmed the result of other groups that an additional genomic ACC synthase (key enzyme of ethylene biosynthesis) sequence ( CsACS1G) should exist in gynoecious genotypes. A linkage was also verified between the F/f locus and the CsACS1G sequence with our plant material. After the exploration of different Southern hybridization patterns originating from different CsACS1 probes, a restriction map of the CsACS1 locus was constructed. By using this restriction map, the duplication of the CsACS1 gene and following mutation of the CsACS1G gene could be explained. The promoter regions of the genes CsACS1G and CsACS1 were amplified in a splinkerette PCR and sequenced. An exclusive amplification of the new isolated sequence ( CsACS1G) in gynoecious ( MMFF) and sub-gynoecious ( MMFf) genotypes confirmed that the isolated gene is the dominant F allele.
A nuclear male-sterile mutant, NMS 360, induced by streptomycin from an inbred maintainer line HA 89, possesses a single recessive gene, ms9, controlling male sterility. The present study identified DNA markers linked to the ms9 gene in an F2 population derived from the cross of NMS 360 x RHA 271 and maps the ms9 gene to an existing sunflower SSR linkage map. Bulked segregant analysis was performed using the target region amplification polymorphism (TRAP) marker technique and the simple sequence repeats (SSR) technique. From 444 primer combinations, six TRAP markers linked with the ms9 gene were amplified. Two markers, Ts4p03-202 and Tt3p09-529, cosegregated with the ms9 gene. The other four markers, To3d14-310, Tt3p17-390, Ts4p23-300, and Tt3p09-531, linked with ms9 at a distance of 1.2, 3.7, 10.3, and 22.3 cM, respectively. Thirty SSR primers from 17 linkage groups of a PHA x PHB cultivated sunflower linkage map were screened among the two parents and the F2 population. SSR primer ORS 705 of linkage group 10 was tightly linked to ms9 at a distance of 1.2 cM. The ms9 gene was subsequently mapped to linkage group 10 of the public sunflower SSR linkage map. The markers that were tightly linked with the ms9 gene will be useful in marker-assisted selection of male-sterile plants among segregating populations, and will facilitate the isolation of the ms9 gene by map-based cloning.
The Aa1-Pri4 gene was cloned from the edible mushroom Agrocybe aegerita. The gene, specifically expressed during fruiting initiation, encodes a glycine-rich protein of 116 amino acids, with no homology to already known proteins. Homologous genes were amplified from two other strains belonging to the Agr. aegerita complex and originating from South-East Asia; and a comparison of the three genes revealed a high conservation of the coding sequences (72.8-97.8%). The PRI4 putative protein sequences were highly similar (87.5-100.0%); and all of them contained two protein kinase C sites, suggesting a potential supplementary regulation by phosphorylation at the protein level. The 5' uncoding regions all presented a leader intron, very variable in sequence (45.7% identity), but with a high C+T content (74.5-79.0%). The presence of such CT-rich sequences previously described in the promoter of highly expressed fungal genes suggests that the leader intron of the Aa1-Pri4 gene could be involved in the high-level, stage-specific expression.
Electrophoretic karyotypes of ten strains of Mucor circinelloides f. lusitanicus were generated by contour-clamped homogeneous electric field (CHEF) gel-electrophoresis. Most of the strains analyzed showed polymorphisms, but a different main karyotype pattern could be correlated with each mating type. Genome structure was further analyzed by gene assignment to the chromosome-sized DNAs. Nonradioactive hybridization techniques identified the chromosomal localization of seven cloned genes. The hybridization patterns confirmed the similarity between the mating-type (-) strains and showed some heterogeneity among the mating-type (+) strains. Linkage was found between genes pyrF and chs3 in all the strains, between the gene leuA and the rDNA in all mating-type (-) strains and ATCC 1216b (+), and between chs2 and the rDNA in CBS 969.68 (+). This is the first time that gene linkage in M. circinelloides has been reported, but in some cases the linkage relationships obtained are strain-dependent.
The heterobasidiomycetes responsible for plant smuts obligatorily require their hosts for the completion of the sexual cycle. Accordingly, the sexual cycle of these fungi could so far be studied only by infecting host plants. We have now induced Ustilago maydis, the causative agent of corn smut, to traverse the whole life cycle by growing mixtures of mating-compatible strains of the fungus on a porous membrane placed on top of embryogenic cell cultures of its host Zea mays. Under these conditions, mating, karyogamy and meiosis take place, and the fungus induces differentiation of the plant cells. These results suggest that embryogenic maize cells produce diffusible compounds needed for completion of the sexual cycle of U. maydis, as the plant does for the pathogen during infection.
An inter-simple sequence repeat (ISSR)-suppression-PCR technique established to develop microsatellite markers of plant species was applied to an ectomycorrhizal fungus, Tricholoma matsutake. Six polymorphic SSR markers were developed. All six polymorphic SSR markers were single-locused and co-dominant. Alleles produced by these six single-locused markers ranged from two to nine per locus and the expected heterozygosities were calculated as values from 0.098 to 0.803. The results indicated that the ISSR-suppression-PCR technique was effective and applicable to the development of microsatellite markers from ectomycorrhizal fungi. Furthermore, the six microsatellite loci did not amplify DNA from any other ectomycorrhizal species investigated, except for Tricholoma nauseosum (Swedish matsutake) and Tricholoma fulvocastaneum, suggesting that population genetics and reproduction of T. matsutake could be investigated by the SSR markers developed in the present study.
Mutations in the S locus of a self-compatible cultivar Yellow Sarson in Brassica rapa, which has a self-compatible class-I S haplotype, S-f2, were investigated. S-28 in Brassica oleracea was found to be a member of an interspecific pair with S-f2 in B. rapa. The original S haplotype of S-f2 was identified to be S-54 in B. rapa. Sequence comparison of alleles in S-f2 with those in S-54 and B. oleracea S-28 revealed insertion of a retrotransposon-like sequence in the first intron of SRK and 89-bp deletion in the promoter region of SP11. No transcripts of SRK and SP11 were detected in S-f2 homozygotes, suggesting that the insertion and the deletion in SRK and SP11, respectively, caused the loss of the function of these genes. Promoter assay using transgenic plants indicated that the SP11 promoter of S-f2 has no activity. Heterozygotes of S-f2 and a normal class-II S haplotype, S-60, in B. rapa were found to be self-compatible. Interestingly, transcription of SP11-60 was revealed to be suppressed in the S-f2/S-60 heterozygotes, suggesting that an untranscribed class-I SP11 allele suppresses the expression of a recessive class-II SP11 allele in the anthers of S heterozygotes. Similar phenomenon was observed in heterozygotes of a self-compatible class-I S haplotype and a self-incompatible class-II S haplotype in B. oleracea.
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