Differential expression of a polygalacturonase gene family in Arabidopsis thaliana

By systematic sequencing of a flower bud cDNA library from Arabidopsis thaliana, we have identified four cDNAs encoding polygalacturonase. The corresponding genes, together with seven other A. thaliana genes present in the databases, form a small gene family. Sequence comparisons of the deduced polypeptides within the gene family or with other plant polygalacturonases allow classification of the genes into different clades. Five polygalacturonases, including all those isolated from the flower buds, are closely related to the enzyme in pollen. Of the six remaining polygalacturonases, three are more closely related to the abscission-specific type of enzyme and two others to the fruit polygalacturonase. The last one is more distantly related to the others and might correspond to a new type of polygalacturonase. Expression of the different genes was analysed on Northern blots and by a PCR-based strategy. Results indicate that if, as expected, the cDNAs isolated from the flower bud library are strongly expressed in pollen, other genes are expressed at a low level in young developing tissues, such as in seedlings and roots, suggesting that they could be implicated in the cell wall modifications observed during cell elongation and/or expansion which occur in these tissues. Received: 7 December 1998 / Accepted: 1 April 1999     

The dopaminergic inhibition of LH secretion during the menstrual cycle

To assess the potential inhibitory role of hypothalamic dopaminergic input on the LRF-LH system, the gonadotropin response to a dopamine receptor antagonist, metoclopramid (MCP, 10 mg iv bolus) was examined during different phases of the menstrual cycle in 12 women. In addition, the role of dopamine infusion on naloxone (opiate receptor antagonist) induced LH increments was examined. MCP induced an abrupt increase in circulating LH levels in the mid-luteal phases but not in the early and late follicular phase subjects. No significant changes in serum FSH levels were observed. Dopamine, when infused concomitantly with naloxone, completely suppressed the naloxone induced pulsatile increments of LH in mid-luteal subjects. These findings support the contention that an increased dopaminergic inhibition of LRF-LH system occurs during the high estrogen-progesterone phase of the menstrual cycle, and provide preliminary evidence that the inhibitory role of endogenous opioids on LRF release may involve the dopaminergic system.     

Development and Evaluation of SoySNP50K,a High-Density Genotyping Array for Soybean

The objective of this research was to identify single nucleotide polymorphisms (SNPs) and to develop an Illumina Infinium BeadChip that contained over 50,000 SNPs from soybean (Glycine max L. Merr.). A total of 498,921,777 reads 35–45bp in length were obtained from DNA sequence analysis of reduced representation libraries from several soybean accessions which included six cultivated and two wild soybean (G. soja Sieb. et Zucc.) genotypes. These reads were mapped to the soybean whole genome sequence and 209,903 SNPs were identified. After applying several filters, a total of 146,161 of the 209,903 SNPs were determined to be ideal candidates for Illumina Infinium II BeadChip design. To equalize the distance between selected SNPs, increase assay success rate, and minimize the number of SNPs with low minor allele frequency, an iteration algorithm based on a selection index was developed and used to select 60,800 SNPs for Infinium BeadChip design. Of the 60,800 SNPs, 50,701 were targeted to euchromatic regions and 10,000 to heterochromatic regions of the 20 soybean chromosomes. In addition, 99 SNPs were targeted to unanchored sequence scaffolds. Of the 60,800 SNPs, a total of 52,041 passed Illumina’s manufacturing phase to produce the SoySNP50K iSelect BeadChip. Validation of the SoySNP50K chip with 96 landrace genotypes, 96 elite cultivars and 96 wild soybean accessions showed that 47,337 SNPs were polymorphic and generated successful SNP allele calls. In addition, 40,841 of the 47,337 SNPs (86%) had minor allele frequencies ≥10% among the landraces, elite cultivars and the wild soybean accessions. A total of 620 and 42 candidate regions which may be associated with domestication and recent selection were identified, respectively. The SoySNP50K iSelect SNP beadchip will be a powerful tool for characterizing soybean genetic diversity and linkage disequilibrium, and for constructing high resolution linkage maps to improve the soybean whole genome sequence assembly.     

Genomic organization and chromosomal localization of three members of the UDP-N-acetylgalactosamine: polypeptide N- acetylgalactosaminyltransferase family

A homologous family of UDP- N -acetylgalactosamine: polypeptide N - acetylgalactosaminyltransferases (GalNAc-transferases) initiate O- glycosylation. These transferases share overall amino acid sequence similarities of approximately 45-50%, but segments with higher similarities of approximately 80% are found in the putative catalytic domain. Here we have characterized the genomic organization of the coding regions of three GalNAc-transferase genes and determined their chromosomal localization. The coding regions of GALNT1 , -T2 , and -T3 were found to span 11, 16, and 10 exons, respectively. Several intron/exon boundaries were conserved within the three genes. One conserved boundary was shared in a homologous C. elegans GalNAc- transferase gene. Fluorescence in situ hybridization showed that GALNT1 , -T2 , and -T3 are localized at chromosomes 18q12-q21, 1q41-q42, and 2q24-q31, respectively. These results suggest that the members of the polypeptide GalNAc-transferase family diverged early in evolution from a common ancestral gene through gene duplication.      

A rapid boiling method for the preparation of bacterial plasmids

Compounds separated on polyamide thin-layers and located in an appropriate manner can be introduced directly into the ion source of the mass spectrometer together with the chromatographic polyamide adsorbent. In spite of the large excess of polyamide, excellent mass spectra are obtained exhibiting low backgrounds. In this way, organic compounds can be rationally identified on a nanogram scale not requiring reference substances. The application of the procedure is described for selected compounds of different classes of substances, e.g., phenols, steroids, nucleosides, biogenic amines, and amino acids.     

Functional dyspepsia and nonerosive reflux disease: clinical interactions and their implications

Functional dyspepsia or nonulcer dyspepsia, and nonerosive reflux disease (NERD) or endoscopy-negative reflux disease, are common reasons for referral to a gastroenterologist. Although there is much confusion with regard to definition, recent research would suggest that these 2 conditions are linked and may represent components in the spectrum of the same disease entity, in terms of both symptoms and pathophysiology. Several theories have been proposed regarding the etiology of these disorders, including acid exposure, visceral hypersensitivity, impaired fundal accommodation, delayed gastric emptying, and Helicobacter pylori infection.     

The mode of host-parasite interaction shapes coevolutionary dynamics and the fate of host cooperation

Antagonistic coevolution between hosts and parasites can have a major impact on host population structures, and hence on the evolution of social traits. Using stochastic modelling techniques in the context of bacteria-virus interactions, we investigate the impact of coevolution across a continuum of host-parasite genetic specificity (specifically, where genotypes have the same infectivity/resistance ranges (matching alleles, MA) to highly variable ranges (gene-for-gene, GFG)) on population genetic structure, and on the social behaviour of the host. We find that host cooperation is more likely to be maintained towards the MA end of the continuum, as the more frequent bottlenecks associated with an MA-like interaction can prevent defector invasion, and can even allow migrant cooperators to invade populations of defectors.     

Identification of novel, orally bioavailable spirohydantoin CGRP receptor antagonists

A rapid analogue approach to identification of spirohydantoin-based CGRP antagonists provided novel, low molecular weight leads. Modification of these leads afforded a series of nanomolar benzimidazolinone-based CGRP receptor antagonists. The oral bioavailability of these antagonists was inversely correlated with polar surface area, suggesting that membrane permeability was a key limitation to absorption. Optimization provided compound 12, a potent CGRP receptor antagonist (K_i = 21 nM) with good oral bioavailability in three species.