Isolation and characterization of new polymorphic simple sequence repeat loci in grape (Vitis vinifera L.).

Four new simple sequence repeat (SSR) loci (designated VVMD5, VVMD6, VVMD7, and VVMD8) were characterized in grape and analyzed by silver staining in 77 cultivars of Vitis vinifera. Amplification products ranged in size from 141 to 263 base pairs (bp). The number of alleles observed per locus ranged from 5 to 11 and the number of diploid genotypes per locus ranged from 13 to 27. At each locus at least 75% of the cultivars were heterozygous. Alleles differing in length by only 1 bp could be distinguished by silver staining, and size estimates were within 1 or 2 bp, depending on the locus, of those obtained by fluorescence detection at previously reported loci. Allele frequencies were generally similar in wine grapes and table grapes, with some exceptions. Some alleles were found only in one of the two groups of cultivars. All 77 cultivars were distinguished by the four loci with the exception of four wine grapes considered to be somatic variants of the same cultivar, 'Pinot noir', 'Pinot gris', 'Pinot blanc', and 'Meunier'; two table grapes that are known to be synonymous, 'Keshmesh' and 'Thompson Seedless'; and three table grapes, 'Dattier', 'Rhazaki Arhanon', and 'Markandi', the first two of which have been suggested to be synonymous. Although the high polymorphism at grape SSR loci suggests that very few loci would theoretically be needed to separate all cultivars, the economic and legal significance of grape variety identification requires the increased resolution that can be provided by a larger number of loci. The ease with which SSR markers and data can be shared internationally should encourage their broad use, which will in turn increase the power of these markers for both identification and genetic analysis of grape. Key words : grape, Vitis, microsatellite, simple sequence repeat, DNA typing, identification.     

Maintenance of Weight Loss: A Needs Assessment

This study identified facilitators and obstacles to maintenance of weight loss following a very-low-calorie-diet and behavior modification program. A survey was mailed to a random sample of 178 program completers and received a 61% response rate; the most frequent follow-up period was more than 2 years. Twenty-nine percent reported weighing the same (within 10 lbs) or less than the end of their participation in the treatment program (maintainers), while 71% reported their present weight was a mean of 65% higher than their initial weight loss (regainers). Maintainers were significantly more likely to report engaging in regular aerobic exercise, attending a maintenance support group, and confidence in their ability to manage their weight in the future, while regainers were more likely to report stress and motivation as frequent weight management obstacles. Respondents consistently identified the need for low/no cost ongoing support. Maintainers and relapsers reported similar challenges in managing their weight, yet with different results, suggesting the need to identify subgroups for which different post-treatment support options could be applied.     

RIBOSOMAL-DNA,MITOCHONDRIAL-DNA,CHROMOSOMAL, AND ALLOZYMIC STUDIES ON A CONTACT ZONE IN THE POCKET GOPHER,GEOMYS

We studied 75 individuals of the Plains pocket gopher, Geomys bursarius, from eastern New Mexico, where the subspecies major and knoxjonesi hybridize. Each individual was examined for chromosome number, ribosomal DNA, mitochondrial DNA, and three protein systems for which reference parental populations were fixed for alternative alleles. Twenty individuals were indistinguishable from parental major, 14 individuals were indistinguishable from parental knoxjonesi, and 41 individuals had genotypes composed of combinations of character states that distinguish the two parental types. The parental types appear to represent discrete genetic entities that have restricted introgression across a narrow hybrid zone (width approximately 3 km, using the 20/80 criterion). Parental types overlap in geographic distribution near the center of the zone, and changes in mitochondrial DNA and the five nuclear markers are concordant across the zone. It is probable that there is premating isolation between knoxjonesi males and major females. The frequencies of individuals with certain genotypic combinations within our sample imply differential reproductive success of certain genotypes. We propose that F₁'s and highly heterozygous males are sterile and that hybrid females are less fertile than parental females. These postmating factors, along with premating isolation for one of the reciprocal crosses, probably account for the restriction of gene flow across the contact zone. The structure of the zone can be explained by the “dynamic equilibrium” model.     

An Ustilago maydis Mutant Partially Blocked in P45014DM Activity Is Hypersensitive to Azole Fungicides

An Ustilago maydis ergosterol biosynthesis mutant (A14) which is partially blocked in sterol 14alpha-demethylase (P45014DM) activity is described. This mutant accumulated the abnormal 14alpha-methyl sterols, eburicol, 14alpha-methylfecosterol, and obtusifoliol, along with significant amounts of ergosterol. Although the A14 mutant grew nearly as well as the wild type, it was impaired in cell extension growth, which indicated a dysfunction in apical cell wall synthesis. The mutant was also found to be hypersensitive to the azole fungicides penconazole and tebuconazole.     

Growth and phage resistance of Anabaena sp. strain PCC 7120 in the presence of cyanophage AN-15

The cyanophage AN-15 was found to have a requirement for either 1 mM calcium or 1 mM magnesium ions to maintain viral stability, whereas 1 mM calcium ions alone were essential for the infection process to proceed in Anabaena sp. strain PCC 7120. Following prolonged incubation, phage-resistant cells were detected at a high frequency (approximately 10-⁵) in lysates, as either renewed growth in liquid cultures, or as colonies in confluently lysed lawns. Southern hybridisation failed to detect AN-15 DNA in any of the resistant strains, implying that resistance is unlikely to be due to the presence of temperate phages. A high rate of spontaneous mutation is therefore likely to be the cause of resistance. Two classes of resistant cells were identified; those in which AN-15 failed to attach to host cells, and those in which attachment occurred, but subsequent replication was defective. However, it was possible to overcome phage resistance by the isolation of spontaneous mutants of AN-15, capable of infecting phage-resistant cells. These observations imply that if cyanophages are to be assessed as a means of controlling cyanobacterial blooms in freshwater bodies, the ionic (notably calcium) concentration of the water must be considered, together with the possible need to employ alternative cyanophage strains if resistance to the original one arises. This revised version was published online in August 2006 with corrections to the Cover Date.     

Comparative evolutionary rates of introns and exons in murine rodents

Analysis of DNA sequences of 132 introns and 140 exons from 42 pairs of orthologous genes of mouse and rat was used to compare patterns of evolutionary change between introns and exons. The mean of the absolute difference in length (measured in base pairs) between the two species was nearly five times as high in the case of introns as in the case of exons. The average rate of nucleotide substitution in introns was very similar to the rate of synonymous substitution in exons, and both were about three times the rate of substitution at nonsynonymous sites in exons. G+C content of introns and exons of the same gene were correlated; but mean G+C content at the third positions of exons was significantly higher than that of introns or positions 1–2 of exons from the same gene. G+C content was conserved over evolutionary time, as indicated by strong correlations between mouse and rat; but the change in G+C content was greatest at position 3 of exons, intermediate in introns, and lowest at positions 1–2 in introns. Received: 23 December 1996 / Accepted: 1 April 1997     

Body fat,rank, and nutritional status in a captive group of Rhesus Macaques

Using weight and skinfold thickness to calculate relative body fat, the fat content of 21 captive female rhesus macaques was estimated. Although age and. pregnancy had no effect on fat, rank was significant, especially during winter, with high-rank females having the highest fat scores. Rank therefore has a significant effect on the health of captive animals and may also affect the health of individuals in feral groups.     

Circulating immune complexes in patients with breast cancer.

In a retrospective study in women with breast cancer circulating immune complex levels were measured by radioimmunoprecipitation with 125I-Clq. Before operation all the patients showed plasma immune complex levels significantly higher than those in controls. Twelve months after mastectomy patients identified clinicopathologically as having a good prognosis had almost normal levels of immune complexes. By contrast, patients with detectable dissemination on diagnosis or those who died within 22 months after mastectomy had significantly raised plasma levels. The tumour-specific nature of the immune complexes detected remains to be shown and suggestions about the applicability of this test not only for prognosis but also for monitoring the course of malignant diseases need to be confirmed by further investigations.