A framework linkage map of perennial ryegrass based on SSR markers.

A moderate-density linkage map for Lolium perenne L. has been constructed based on 376 simple sequence repeat (SSR) markers. Approximately one third (124) of the SSR markers were developed from GeneThresher libraries that preferentially select genomic DNA clones from the gene-rich unmethylated portion of the genome. The remaining SSR marker loci were generated from either SSR-enriched genomic libraries (247) or ESTs (5). Forty-five percent of the GeneThresher SSRs were associated with an expressed gene. Unlike EST-derived SSR markers, GeneThresher SSRs were often associated with genes expressed at a low level, such as transcription factors. The map constructed here fulfills 2 definitions of a "framework map". Firstly, it is composed of codominant markers to ensure map transferability either within or among species. Secondly, it was constructed to achieve a level of statistical confidence in the support-for-order of marker loci. The map consists of 81 framework SSR markers spread over 7 linkage groups, the same as the haploid chromosome number. Most of the remaining 295 SSR markers have been placed into their most likely interval on the framework map. Nine RFLP markers and 1 SSR marker from another map constructed using the same pedigree were also incorporated to extend genome coverage at the terminal ends of 5 linkage groups. The final map provides a robust framework with which to conduct investigations into the genetic architecture of trait variation in this commercially important grass species.

Riding the Ice Age El Nino? Pacific biogeography and evolution of Metrosideros subg. Metrosideros (Myrtaceae) inferred from nuclear ribosomal DNA.

Metrosideros subg. Metrosideros (Myrtaceae) comprises approximately 26 species distributed widely across the Pacific basin. They occur on the ancient Gondwanan landmasses of New Zealand and New Caledonia, as well as on the volcanic islands of the remote Pacific, from Melanesia to tropical Polynesia and the Bonin Island. Phylogenetic analysis based on nuclear ribosomal DNA spacer sequences from all named species showed Metrosideros umbellata of New Zealand as basal in the subgenus, with the remaining species falling into three monophyletic clades. One includes the seven New Caledonian species together with three daughters in western Oceania that probably dispersed during the mid/late Tertiary. A second contains six taxa located in east Melanesia and Samoa that may also have arisen from a mid/late Tertiary dispersal, in this instance from New Zealand. The third includes three New Zealand endemics along with all of the taxa in remote Polynesia and accounts for much of the total range of the subgenus. These dispersed taxa in Polynesia either are identical to the New Zealand species Metrosideros excelsa or differ by a single nucleotide change. We suggest that they are all derived from a Pleistocene dispersal out of New Zealand. A relatively recent dispersal is surprising, given that this wind-dispersed genus has occupied New Zealand for much of the Tertiary and that some of the islands in remote Polynesia date to at least the Miocene. We attribute this dramatic range expansion to climate change-specifically changes in wind flow patterns-in the southern hemisphere during worldwide glaciation.

Gene-specific changes in alpha-tubulin transcript accumulation in developing cotton fibers.

The fibers of cotton (Gossypium hirsutum) are single-cell trichomes that undergo rapid and synchronous elongation. Cortical microtubules provide spatial information necessary for the alignment of cellulose microfibrils that confine and regulate cell elongation. We used gene-specific probes to investigate alpha-tubulin transcript levels in elongating cotton fibers. Two discrete patterns of transcript accumulation were observed. Whereas transcripts of alpha-tubulin genes GhTua2/3 and GhTua4 increased in abundance from 10 to 20 d post anthesis (DPA), GhTua1 and GhTua5 transcripts were abundant only through to 14 DPA, and dropped significantly at 16 DPA with the onset of secondary wall synthesis. This is the first report, to our knowledge, of gene-specific changes in tubulin transcript levels during the development of a terminally differentiated plant cell. The decrease in abundance of GhTua1 and GhTua5 transcripts was correlated with pronounced changes in cell wall structure, suggesting that alpha-tubulin isoforms may be functionally distinct in elongating fiber cells. Although total alpha-tubulin transcript levels were much higher in fiber than several other tissues, including the hypocotyl and pollen, none of the alpha-tubulins was specific to fiber cells.

Expression of ethylene biosynthetic genes in Actinidia chinensis fruit.

The fruit of Actinidia chinensis, a diploid relative of kiwifruit, showed an increased rate of ripening in response to the application of exogenous ethylene. Moreover, late in ripening the fruit produced a burst of ethylene biosynthesis. Thus ripening is climacteric, and there is a clear temporal separation of ethylene sensitivity and ethylene production. RNase protection assays were used to monitor transcript levels of ethylene biosynthetic genes during fruit development and ethylene-induced ripening. The application of exogenous ethylene correlated with increased transcript levels for three different S-adenosyl-L-methionine (SAM) synthetase genes and for the 1-aminocyclopropane-1-carboxylate (ACC) oxidase gene family. Transcription of an ACC synthase gene was not affected by exogenous ethylene. However, ACC synthase transcript levels increased during subsequent ethylene production by the fruit, consistent with this being the control step for the onset of climacteric ethylene production. ACC oxidase transcripts increased significantly both prior to and during climacteric ethylene production, while only one of the three SAM synthetase transcripts was induced during the late ethylene burst. We propose that the regulation of SAM synthetase transcripts by ethylene may occur as part of the methionine salvage pathway.

Oxytocin stimulates the release of arachidonic acid and prostaglandin F2 alpha from human decidual cells.

Oxytocin at a physiological concentration stimulated the immediate release of free arachidonic acid from dispersed human decidual cells in a perfusion system. This indicates that oxytocin activates phospholipase(s) thus enhancing prostaglandin synthesis. The effect of oxytocin on the release of [3H]-arachidonic acid from decidual cells of women in labor was significantly greater (1036 +/- 207, mean dpm +/- SEM, n = 23) than from those of women not-in-labor (505 +/- 121 dpm, n = 12) or with endometrial cells of non-pregnant women (711 +/- 210 dpm, n = 18), and correlates well with reported oxytocin receptor concentrations in these tissues. These new findings are consistent with a role for endogenous oxytocin in stimulating prostaglandin synthesis at the onset of parturition.

Diet, nutrition intake, and metabolism in populations at high and low risk for colon cancer. Population: demographic and anthropometric characteristics.

A study was designed to compare nutritional and metabolic parameters on subjects with a spectrum of vegetarian and nonvegetarian dietary patterns. The method of selection of the study population, the description of its characteristics, and the data collection protocol are described. Anthropometric measurements of vegetarians and nonvegetarians are reported and compared with previously reported measurements on similar populations.

Diet, nutrition intake, and metabolism in populations at high and low risk for colon cancer. Nutrient intake.

A 3-day diary with portion sizes weighed by the subject and a 24-h recall were obtained on 50 sets of subjects: Seventh-day Adventist lacto-ovo-vegetarians and nonvegetarians, and general population nonvegetarians, matched on age (+/- 5 yr), sex, marital status, education, type of milk preferred, and an index of the frequency of dairy and egg product use. An additional 18 unmatched persons who follow a pure vegetarian dietary pattern (use no meat, fish, fowl, dairy, or egg products) were recruited into the study. The rational for the dietary methods used is presented and details of each of the methods used are given. The results of the nutrient analysis of the 24-h recall and 3-day diary are presented. The 3-day nutrient intake means for the four groups are compared to the sex-specific recommended daily allowance both with and without supplements. The contribution of nutritional supplements to the nutrient intake is discussed. All groups show adequate or excess intake levels of calories, protein, and fat when either the 24-h recall or the 3-day diary values are considered. The higher intake of calories noted among nonvegetarians can be explained by a higher intake of both fat and protein in these groups. A, B, and C vitamin levels (3-day dairy estimates) are adequate both with and without supplements. Calcium intake is much below recommended levels for pure vegetarian females. Iron intake is low for all females. A heme iron source does not improve the intake levels for nonvegetarian females. A comparison of these results with prior reports of nutrient intake among Seventh-day Adventists is presented.