Clustering of Y chromosome deletions in subinterval E of interval 6 supports the existence of an oligozoospermia critical region outside the DAZ gene

Y chromosome molecular analysis was performed using the STS-PCR technique in 50 patients with oligozoospermia. Microdeletions of interval 6 of the Y chromosome were detected in seven patients, in six of whom subinterval E was affected. All patients retained the RBM1 and DAZ genes, while in one deletion involved the SPGY gene. The size of the deletion was not apparently related to the severity of the disease. These results suggest the presence of an oligozoospermia critical region on the Y chromosome within subinterval E of interval 6.     

Part of the RBM gene cluster is located distally to the DAZ gene cluster in human Yq11.23

Normal human Y and inverted Y chromosomes were chosen for physical fluorescence in situ hybridization (FISH) mapping of RBM and DAZ probes for the relative positioning of the RBM and DAZ gene clusters in interval 6 of the human Y chromosome. The inversion breakpoint in Yq11.23 turned out to be distal to the DAZ gene cluster, as the entire DAZ signal appears in the short arm of the inv(Y) chromosome. On the contrary, this inversion breakpoint in Yq11.23 divides the RBM signal cluster, leaving a weaker signal on the long arm while bringing the main RBM signal to the short arm of the inv(Y) chromosome. Thus, it can be concluded that, in contrast to previous claims, part of the RBM gene cluster is located distally to the DAZ gene cluster in deletion interval 6 of the human Y chromosome.     

Nature and regulation of pistil-expressed genes in tomato

The specialized reproductive functions of angiosperm pistils are dependent in part upon the regulated activation of numerous genes expressed predominantly in this organ system. To better understand the nature of these pistil-predominant gene products we have analyzed seven cDNA clones isolated from tomato pistils through differential hybridization screening. Six of the seven cDNAs represent sequences previously undescribed in tomato, each having a unique pistil- and/or floral-predominant expression pattern. The putative protein products encoded by six of the cDNAs have been identified by their similarity to sequences in the database of previously sequenced genes, with a seventh sequence having no significant similarity with any previously reported sequence. Three of the putative proteins appear to be targeted to the endomembrane system and include an endo-beta-1,4-glucanase which is expressed exclusively in pistils at early stages of development, and proteins similar in sequence to gamma-thionin and miraculin which are expressed in immature pistils and stamens, and in either sepals or petals, respectively. Two other clones, similar in sequence to each other, were expressed primarily in immature pistils and stamens and encode distinct proteins with similarity to leucine aminopeptidases. An additional clone, which encodes a protein similar in sequence to the enzyme hyoscyamine 6-beta-hydroxylase and to other members of the family of Fe2+/ascorbate-dependent oxidases, was expressed at high levels in pistils, stamens and sepals, and at detectable levels in some vegetative organs. Together, these observations provide new insight into the nature and possible functional roles of genes expressed during reproductive development.     

Assembly of the zygotic centrosome in the fertilized Drosophila egg

Large-scale cDNA analysis provides several great advantages for genome investigations in rice. Isolated and partially characterized cDNA clones have contributed not only to the construction of an RFLP linkage map and physical maps of the chromosomes but also to investigations of the mechanisms of expression of various isozymes and family genes. The ultimate aim of our large-scale cDNA analysis is to catalogue all the expressed genes of this important cereal, including tissue-specific, developmental stage-specific, and stress-specific genes. As of August 1996, the Rice Genome Research Program (RGP) has isolated and partially sequenced more than 29,000 cDNA clones from various tissues and calluses in rice (Nipponbare, a japonica variety). The sequence data were translated into amino acid sequences for the 3 possible reading frames, and the similarity of these amino acid sequences to known proteins registered in PIR were examined. About 25% of the clones had significant similarities to known proteins. Some of the hit clones showed library-specific distributions, indicating that the composition of the clones in each library reflects, to some extent, the regulation of gene expression specific to differentiation, growth condition, or environmental stress. To further characterize the cDNA clones, including unknown clones, nucleotide sequence similarities of 24,728 clones were analyzed and the clones were classified into around 10,000 independent groups, suggesting that around a half or one third of expressed genes in rice have already been captured. These results obtained from our large-scale cDNA analysis provide useful information related to gene expression and regulation in rice.     

Cloning and characterization of a mouse brain calcitonin receptor complementary deoxyribonucleic acid and mapping of the calcitonin receptor gene

We have identified and characterized a mouse brain calcitonin receptor (CTR) complementary DNA (cDNA). This cDNA encodes a receptor protein that, after expression, has high affinity binding for salmon calcitonin (Kd approximately, 12.5 nM) and is coupled to adenylate cyclase. The binding affinity of this expressed receptor for salmon calcitonin is lower than that described for the previously cloned porcine renal and human ovarian CTRs, but is similar to that of the recently described rat brain CTR, designated the C1b form of the receptor. Analysis of the deduced structure of the mouse brain CTR reveals that it is highly related to the other CTR cDNAs that belong to a distinct family of G-protein-coupled receptors with seven transmembrane-spanning domains. The major structural feature that distinguishes the mouse cDNA clone from the other CTRs is the presence of a consecutive 111-basepair nucleotide sequence that encodes a 37-amino acid sequence which is predicted to localize to the first extracellular loop between the second and third transmembrane-spanning domains. We have mapped the CTR gene in the mouse to the proximal region of chromosome 6, which is homologous to the 7q region of human chromosome 7; only a single CTR gene was identified. Preliminary analysis of the mouse CTR gene reveals that it is complex, consisting of multiple exons separated by lengthy introns that would allow for splice variants consistent with the existence of multiple CTR isoforms predicted from the CTR cDNA clones. The differential cellular and tissue distribution of these functionally distinct CTR isoforms provides the molecular basis for the previously reported widespread distribution and functional heterogeneity of the CTR.     

Cloning and expression of five myb-related genes from rice seed

Three elements in the promoter of rice glutelin genes are important for their endosperm specific expression. One of these, an AACA motif, has been shown to be a negative regulator in non-seed tissues and has a similarity to the barley gibberellin responsive element recognized by MYB-like DNA binding proteins. A cDNA library constructed from immature rice seed was screened using two types of myb gene probes to isolate cDNA clones representing genes encoding MYB-like DNA binding proteins that may recognize the AACA motif in rice glutelin gene promoter. We obtained four cDNA clones encoding MYB-related proteins, Oryza sativa MYB (OSMYB) 1-4, using the maize C1 probe. Another myb-like clone, Osmyb5, was obtained by screening a rice seed cDNA library with probes designed to recognize the AACA-like binding domain in GAMYB and PHMYB3. RT-PCR was used to analyze Osmyb expression during rice seed development and their presence in other rice tissues, as it was not possible to detect these mRNAs by conventional Northern analysis. RT-PCR analysis showed that Osmyb2, Osmyb3 and Osmyb5 genes were expressed in all tissues examined. In seed, the mRNA levels of Osmyb1 and Osmyb4 genes reached a maximum at 14 days after flowering (DAF), suggesting that these genes may play a role in seed maturation. As Osmyb5 exhibits a high similarity to the regions in both GAMYB and PHMYB3, which can bind to the AACA motif, there is a possibility that the OSMYB5 protein may bind to the AACA motif of glutelin genes.