QTL mapping for two commercial traits in farmed saltwater crocodiles (Crocodylus porosus).

The recent generation of a genetic linkage map for the saltwater crocodile (Crocodylus porosus) has now made it possible to carry out the systematic searches necessary for the identification of quantitative trait loci (QTL) affecting traits of economic, as well as evolutionary, importance in crocodilians. In this study, we conducted genome-wide scans for two commercially important traits, inventory head length (which is highly correlated with growth rate) and number of scale rows (SR, a skin quality trait), for the existence of QTL in a commercial population of saltwater crocodiles at Darwin Crocodile Farm, Northern Territory, Australia. To account for the uncommonly large difference in sex-specific recombination rates apparent in the saltwater crocodile, a duel mapping strategy was employed. This strategy employed a sib-pair analysis to take advantage of our full-sib pedigree structure, together with a half-sib analysis to account for, and take advantage of, the large difference in sex-specific recombination frequencies. Using these approaches, two putative QTL regions were identified for SR on linkage group 1 (LG1) at 36 cM, and on LG12 at 0 cM. The QTL identified in this investigation represent the first for a crocodilian and indeed for any non-avian member of the Class Reptilia. Mapping of QTL is an important first step towards the identification of genes and causal mutations for commercially important traits and the development of selection tools for implementation in crocodile breeding programmes for the industry.

Standardized reference ideogram for physical mapping in the saltwater crocodile (Crocodylus porosus).

Basic cytogenetic data, such as diploid number and general chromosome morphology, are available for many reptilian species. Here we present a detailed cytogenetic examination of the saltwater crocodile (Crocodylus porosus) karyotype, including the creation of the first fully annotated G-band standard ideogram for any crocodilian species. The C. porosus karyotype contains macrochromosomes and has a diploid number of 34. This study presents a detailed description of each chromosome, permitting unambiguous chromosome identification. The fully annotated standardized C. porosus ideogram provides the backbone to a standard nomenclature system which can be used to accurately identify specific band locations. Seven microsatellite containing fosmid clones were fluorescently labeled and used as fluorescent in situ hybridization (FISH) probes for physical localization. Chromosome locations for each of these FISH probes were successfully assigned, demonstrating the utility of the fully annotated ideogram for genome mapping.

Can family attributes explain the racial disparity in living kidney donation?

BACKGROUND: Living donation is a safe, effective treatment for patients with end-stage renal disease (ESRD), yet rates of live kidney donation remain low. Potential transplant recipients may be more inclined to ask a family member for a living donation if they feel familial closeness. METHODS: The FACES II and the Living Organ Donor Survey were administered to patients attending pretransplant education to assess individual perceptions of family structure and willingness to request a living kidney donation from a family member. RESULTS: A total of 328 potential transplant recipients were included in the study: 200 (61%) African American and 128 (39%) Caucasian. Approximately half were willing to ask for a living donation. Individual's perception of family cohesion, adaptability, and type as measured by FACES II showed most families were mid-range with optimal cohesion and adaptability. Family cohesion and adaptability showed no association with being willing to request a live donation, but those single/never married were only half as likely to ask for donation (odds Ratio [OR] 0.51; 95% confidence interval [CI] 0.31-0.86, P = .01). Lower education (beta = -0.49) and unmarried status (beta = -0.31) predicted a lower cohesion score. CONCLUSION: Family type, cohesion, and adaptability showed no differences across race and was not related to the potential recipient's willingness to ask for a live donation. Although responses by race did not differ, an important finding showed that only half of ESRD patients are willing to ask for a live organ donation, and those patients that were single/never married were less likely to ask for a living donation. Research surrounding this reluctance is warranted.