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Saline-tolerance has evolved in mosquito larvae several times in various genera. The Ochlerotatusgenus is of interest because there are both freshwater and saline-tolerant forms within this group and both forms are osmoregulators. The physiological ability to cope with saline water versus freshwater in the Ochlemtatus mosquitoes is associated with a morphological difference in the rectum, an organ that serves an osmoregulatory function in these insects. The saline-tolerant forms have a two-part rectum while the freshwater obligates have a one-part rectum. Of the many species of this genus whose saline-tolerance has not been described, we have collected several in their larval stages. Our study includes 16 Ochlerotatus species collected in North America and one closely related and saline-tolerant New Zealand Opifex species. For each species we performed a morphological analysis of the larval recta. To determine saline-tolerance, mosquito larvae were gradually taken from dilute water to water adjusted up to 1000 mOsm using InstantOcean. Those with high survival to pupation in solutions up to 1000 mOsm were determined to be saline-tolerant. We then looked at the evolutionary patterns of saline-tolerance in this genus by mapping this character onto a phylogenetic tree. We constructed this tree by PCR amplifying and direct sequencing of the 18s rDNA gene, the D2 region of the 28s rDNA gene and two mitochondrial genes, COI and COII for each species. We then used PAUP 4.0 to construct and analyze a phylogenetic tree. Our tree does not suggest a single point when the saline-tolerant and freshwater forms split. Instead, it provides evidence that saline-tolerance evolved once from a freshwater ancestor and was subsequently lost or arose multiple times.

Of the mosquito species belonging to the genus, Ochlerotatus, several have been shown to be saline-tolerant as aquatic larvae while others are restricted to freshwater. This saline-tolerance is associated with a morphological difference in the rectum, an organ that serves an osmoregulatory function in these insects. The saline-tolerant forms have a two-part rectum while the freshwater obligates have a one-part rectum. Of the many species among this genus whose saline-tolerance has not been described, we have collected several in their larval stages. Upon collections we have performed a salinity assay and a morphological analysis of the rectum. To determine saline-tolerance, mosquito larvae were gradually taken from dilute waters to 1000 mOsm. Those with high survival to pupation in solutions up to 1000 mOsm were determined to be saline-tolerant. We then looked at the evolutionary patterns of saline-tolerance in this genus by mapping this character onto a phylogenetic tree. We constructed this tree by direct sequencing the 18s rRNA gene and the D2 region of the 28s rRNA gene for each species and used MEGA3 software to assemble the tree. This robust tree does not indicate a single point when the saline-tolerant and intolerant forms split. Instead, it is evidence that saline-tolerance evolved once and was subsequently lost or arose multiple times.

We investigated the effect of dehydration and subsequent rehydration on fecundity in five populations of Drosophila melanogaster selected for enhanced desiccation resistance (D populations) and their five paired control populations (C populations). Female flies were desiccated for 8h (C populations) or 24h (D populations) and then allowed to recover for 48h on distilled water, a saline solution, a saline+sucrose solution or on food. Each of these was tested with or without a yeast supplement. Flies were then placed individually in vials of food for 12h and the number of eggs laid during this time period was measured. Fecundity was also measured during the same 12h on flies that did not undergo a desiccation stress but were instead given food throughout the experiment. The flies that recovered in the presence of yeast had a greater fecundity within a specific recovery treatment than those flies recovering without yeast. The relative importance of osmotic recovery and dietary supplementation on fecundity will be discussed. The D populations showed a greatly reduced fecundity relative to the C populations when all populations were given yeast or when flies had not undergone desiccation. This reduced fecundity may be the result of a physiological trade-off due to high carbohydrate and low lipid levels in the D populations, a characteristic that has been positively correlated with desiccation resistance. A single bout of dehydration in flies of the C and D populations had no measurable effect on fecundity provided the flies are given a recovery period. Supported by NSF grant IBN 0079501

We have examined osmoregulatory ability in the insect Drosophila melanogasterby measuring hemolymph osmotic concentration during desiccation. Hemolymph osmolality was determined using melting point depression measured with a Clifton nanolitre osmometer. We compared the osmoregulatory abilities of flies from five populations which have undergone selection for over 250 generations for enhanced desiccation resistance (D populations) to those of flies from five control populations (C populations). The Ds were measured upon the initiation of a bout of desiccation (time 0) and at 8,16, 24, and 48h of desiccation. The Cs were measured at 0, 8 and 16h of desiccation. All populations display a high variability in hemolymph osmolality at each measured interval. Hemolymph osmolality increases linearly as a function of the proportional hemolymph dehydration in all C and D populations. Based on the previously quantified average hemolymph volumes of each population, the increase in hemolymph osmotic concentration is significantly lower than what is expected in the absence of osmoregulation (p0.1). Supported by NSF grant IBN-0079501

Disparities exist in the health, livelihood, and opportunities for the 46-60 million people living in America's rural communities. Rural communities across the United States need a new energy and focus concentrated around health and health care that allows for the designing capturing, and spreading of existing and new innovations. This paper aims to provide a framework for policy solutions to build a healthier rural America describing both the current state of rural health policy and the policies and practices in states that could be used as a national model for positive change.