Genetic analysis and mapping of gene fzp(t) controlling spikelet differentiation in rice

A mutant of spikelet differentiation in rice called frizzle panicle (fzp) was discovered in the progeny of a cross between Oryza sativa ssp. indica cv. V20B and cv. Hua1B. The mutant exhibits normal plant morphology but has apparently fewer tillers. The most striking change in fzp is that its spikelet differentiation is completely blocked, with unlimited subsequent rachis branches generated from the positions where spikelets normally develop in wild-type plants. Genetic analysis suggests that fzp is controlled by a single recessive gene, which is temporarily named fzp (t). Based on its mutant phenotype, fzp (t) represents a key gene controlling spikelet differentiation. Some F2 mutant plants derived from various genetic background appeared as the "middle type", suggesting that the action of fzp (t) is influenced by the presence of redundant, modifier or interactive genes. By using simple sequence repeat (SSR) markers and bulked segregant analysis (BSA) method, fzp (t) gene was mapped in the terminal region of the long arm of chromosome 7, with RM172 and RM248 on one side, 3.2 cM and 6.4 cM from fzp (t), and RM18 and RM234 on the other side, 23.1 cM and 26.3 cM from fzp(t), respectively. These results will facilitate the positional cloning and function studies of the gene.     

Cloning, mapping and mutation analysis of human gene GJB5 encoding gap junction protein b-5

By homologous EST searching and nested PCR a new human gene GJB5encoding gap junction protein b-5 was identified. GJB5 was genetically mapped to human chromosome 1p33-p35 by FISH. RT-PCR revealed that it was expressed in skin, placenta and fetal skin. DNA sequencing of GJB5 was carried out in 142 patients with sensorineural hearing impairment and probands of 36 families with genetic diseases, including erythrokeratodermia (5 families), Charcot-Marie-Tooth disease (13), ptosis (4), and retinitis pigmentosa and deafness (14). Two missense mutations (686A→G, H229R; 25C→T, L9F) were detected in two sensorineural hearing impairment families. A heterologous deletion of 18 bp within intron was found in 3 families with heredity hearing impairment, and in one of the 3 families, a missense mutation (R265P) was identified also. But the deletion and missense mutation seemed not segregating with hearing impairment in the family. No abnormal mRNA or mRNA expression was detected in deletion carriers by RT-PCR analysis in skin tissue. Mutation analysis in 199 unaffected individuals revealed that two of them were carriers with the same 18 bp deletion.     

Molecular genetic mapping and plant evolutionary biology

With the advent of molecular genetic mapping, it is possible to study the genetic basis of natural heritable variation in new ways. Here, three potential uses of molecular genetic mapping in plant ecology and evolutionary biology are discussed; (1) accurate estimation of genetic parameters, (2) understanding speciation and/or adaptation, and (3) investigating whole genome organization. Basic methods for mapping genes and important mapping strategies are outlined. Recent studies are introduced to illustrate progress so far in applying the new methods in ecological and evolutionary research.     

Inheritance in turnip of variable-number tandem-repeat genetic markers revealed with synthetic repetitive DNA probes

Oligomers (16–26 mers) composed of short, tandemly repeated DNA sequences (3–10 bases) were used individually with their complementary oligomer in separate polymerase chain reactions (PCRs) that extended the number of repeats to make 15 different PCR synthetic tandem-repeat (STR) probes. These PCR-STR probes were used to examine the inheritance of variable-number tandem-repeat (VNTR) genetic markers from two parent plants of turnip (Brassica rapa L.) to 20 offspring. Following HinfI digestion and PCR-STR probing of Southern blots, interpretable variable parental and offspring band profiles were found with 9 of the 15 probes used. Each of these nine probes produced a unique set of fragments, and no cases of different probes revealing the same fragment were detected. Seventy-nine parental fragments were found and, of these, 65% (51) appeared to be heterozygous in one or both parents, with 52% (41) appearing to be heterozygous in one of the parents exclusively. That these fragments are transmitted as though heterozygous in the parents implies that they are derived from the nuclear complement of the genome. Chi-square analyses of the transmission of markers are, in general, consistent with Mendelian expectations, although three non-parental bands were found accounting for approximately 0.5% of these transmitted bands. For the fragments heterozygous in one of the parents exclusively, seven alleles exhibited complete linkage in three groups, 12 alleles were incompletely linked in six groups, and four allelic groups involving 11 alleles were identified. PCR-STR probes are relatively rapid to generate and apply (no cloning, clone screening, or sequencing steps are required), and have been shown to reveal VNTR genetic markers in a wide variety of plant species. These results add to the list of studies showing that VNTR genetic markers (and in this case, markers revealed by PCR-STR probes) are transmitted for the greater part in a Mendelian fashion.     

Duplicate sequences with a similarity to expressed genes in the genome of Arabidopsis thaliana

The proportion of non-tandem duplicated loci detected by DNA hybridization and the segregation of RFLPs using 90 independent randomly isolated cDNA probes was estimated by segregation analysis to be 17%. The 14 cDNA probes showing duplicate loci in progeny derived from a cross between Arabidopsis-thaliana ecotypes Columbia x Landsberg erecta detected an average of 3.6 loci per probe (ranging from 2 to 6). The 50 loci detected with these 14 probes were arranged on a genetic map of 587 cM and assigned to the five A. Thaliana chromosomes. An additional duplicated locus was detected in progeny from a cross between Landsberg erecta x Niederzenz. The majority of duplicated loci were on different chromosomes, and when linkage between duplicate locus pairs was detected, these loci were always separated by at least 15 cM. When partial nucleotide sequence data were compared with GENBANK databases, the identities of 2 cDNA clones which recognized duplicate unlinked sequences in the A. Thaliana genome were determined to encode a chlorophyll a/b-binding protein and a beta-tubulin. Of the 8 loci carrying beta-tubulin genes 6 were placed on the genetic map. These results imply that gene duplication has been an important factor in the evolution of the Arabidopsis genome.     

鸡痘病毒表达载体的构建Ⅰ、鸡痘病毒282E_4株基因组PstⅠ、HindⅢ酶切片段的克隆及酶切分析

本文介绍了鸡痘病毒２８２Ｅ４株基团组ＰｓｔⅠ片段、ＨｉｎｄⅢ片段的克隆和鉴定,以及部分克隆的限制性内切酶分析。鸡痘病毒基因组经酶切、克隆分别得到３４９个、２７７个白色菌落,经质粒电泳、菌落杂交筛选分别得到２８６、２３４个重组菌落,再经酶切、斑卢、杂交鉴定,证明了所克隆的确为鸡痘病毒的ＰｓｔⅠ、ＨｉｎｄⅢ片段。最后经单、双酶切分析,得到了５个ｐＦＰ、５个ｐＦＨ克隆的物理图谱。     

Purification and genetic control of NAD-dependent glutamate dehydrogenase from Drosophila melanogaster

Glutamate dehydrogenase has been purified to near-homogeneity from mature larvae of Drosophila melanogaster. The enzyme has a molecular weight of 347,000 measured by sucrose gradient sedimentation and 343,000 measured by variable-porosity acrylamide gel electrophoresis. Electrophoresis under denaturing conditions showed that the enzyme consists of six subunits of molecular weight 57,000. The structural gene for GDH has been mapped at 81.7±0.8 on the third chromosome by means of an electrophoretic variant.This work was supported by CNR Contract 76-01961-04.     

Collagen-Induced Changes in the Pattern of Protein Synthesis of Fibroblasts

Cells were cultured on plastic, collagen fibrils or gelatin. General protein synthetic activity of cells did not show any significant, difference among the three substrates, whereas the pattern of protein synthesis was substrate-dependent. Profiles of protein synthesis (polypeptide maps) were obtained by subjecting two-dimensional autoradiograms of poly-acrylamide gel electrophoresis to a computer-assisted image analyzer. Major polypeptide spots expressed on gelatin were rather like those on plastic. Collagen fibrils caused significant changes in the polypeptides map. Fibroblasts on collagen fibrils produced 364 spots of polypeptides, 26% of which were synthesized specifically on collagen fibrils. The remaining was shared by cells on plastic and was categorized into three groups: (1) polypeptides whose synthesis was up-regulated by collagen fibrils (26% of the total); (2) polypeptides that were expressed equally on both plastic and collagen fibrils (51%); and (3) polypeptides down-regulated by'collagen fibrils (23%). A protein with molecular weight of 150 K and an isoelectric point (pI) of 7.3 was one of the collagen-induced and worthy of further analysis. This protein was found to change its pi depending upon the amounts of collagen fibrils and was shown to be located in the mitochondrial fraction.     

An efficient algorithm in the grand canonical ensemble: constructing adsorption isotherms

A new computational method is presented that efficiently describes open thermodynamic systems within the grand canonical ensemble formalism. The method is based on the j-walking algorithm, which circumvent sampling difficulties by coupling random walkers in different thermodynamic states. By imposing detailed balance, a new acceptance probability is derived and applied to the construction of adsorption isotherms for atomic monolayers. The method converges much faster than the standard grand canonical Monte Carlo method and permits the construction of accurate adsorption isotherms and the identification of phase transitions occurring in the adsorbed material.     

The macrophytic vegetation of Loch Urigill and other lochs of the Ullapool area

Summary

From the 15 lochs examined at altitudes between 9 and 267 m in western Sutherland and Wester Ross, a few areas of tall fen (with Hippuris, Sparganium erectum, Osmunda etc.) survive to indicate its potential distribution. Predominant grazed fen comprises patches of short Juncus articulatus and Carex nigra. Reedswamp is scarce, being dominated by Eleocharis palustris, Carex lasiocarpa and Schoenoplectus lacustris and, rarely, by Phragmites and Sparganium erectum. Floating-leaved vegetation was only encountered twice. Submerged vegetation to water depths of at least 1 m consists in the main of sparse Lobelia-Littorella with Juncus bulbosus, typical of the prevailing stony shores in every loch. Extensive Isoetes lacustris meadows may occur beyond that, with Potamogeton praelongus or P. perfoliatus stands in waters of alkalinities over 0·45 m-equiv 1^-1, reaching depths of 3 m in Loch Urigill. Loch Urigill is unusual in having dominant Isoetes at a water alkalinity of 0·76 m-equiv 1^-1 along with abundant Anabaena species and some Potamogeton filiformis.