Isolation of auxotrophic mutants and development of conjugation system in KISR methylotrophs

Isolation of auxotrophic mutants and conjugal transfer of plasmids are successfully demonstrated in four obligate methylotrophic strains isolated at Kuwait Institute for Scientific Research (KISR)Out of 11 auxotrophic, mutants, three required methionine and two leucine. Complete transfer of plasmid R68.45 from Pseudomonasto KISR methylotrophs and vice versa have been achieved with a low transfer rate.     

An evaluation of inbreeding measures using a whole-genome sequenced cattle pedigree

The estimation of the inbreeding coefficient (F) is essential for the study of inbreeding depression (ID) or for the management of populations under conservation. Several methods have been proposed to estimate the realized F using genetic markers, but it remains unclear which one should be used. Here we used whole-genome sequence data for 245 individuals from a Holstein cattle pedigree to empirically evaluate which estimators best capture homozygosity at variants causing ID, such as rare deleterious alleles or loci presenting heterozygote advantage and segregating at intermediate frequency. Estimators relying on the correlation between uniting gametes (F_UNI) or on the genomic relationships (F_GRM) presented the highest correlations with these variants. However, homozygosity at rare alleles remained poorly captured. A second group of estimators relying on excess homozygosity (F_HOM), homozygous-by-descent segments (F_HBD), runs-of-homozygosity (F_ROH) or on the known genealogy (F_PED) was better at capturing whole-genome homozygosity, reflecting the consequences of inbreeding on all variants, and for young alleles with low to moderate frequencies (0.10 < . < 0.25). The results indicate that F_UNI and F_GRM might present a stronger association with ID. However, the situation might be different when recessive deleterious alleles reach higher frequencies, such as in populations with a small effective population size. For locus-specific inbreeding measures or at low marker density, the ranking of the methods can also change as F_HBD makes better use of the information from neighboring markers. Finally, we confirmed that genomic measures are in general superior to pedigree-based estimates. In particular, F_PED was uncorrelated with locus-specific homozygosity.Subject terms: Conservation genomics, Animal breeding, Inbreeding     

Reproduction in the Malayan freshwater cerithiacean gastropod Melanoides tuberculata

Melanoides tuberculata in the Kuala Lumpur area of Malaysia were found to be entirely female, reproducing parthenogenetically. The reproductive system is extremely simple in structure and histology, lacking all the glandular developments common in most mesogastropods. Eggs pass into a cephalic brood-pouch where they develop to juveniles of 5–6 shell whorls before emergence. Numbers of developing young in the brood-pouches increased with shell height of the parents except for a decline in the few very largest snails. The highest brood-pouch count was 265, but average counts were much lower. 85 % of developing young in the brood-pouches were very early stages from eggs to embryos of one whorl only, perhaps implying that many eggs fail to develop successfully to young snails. Three localities studied yielded consistently different brood-pouch counts, implying variation in fecundity. Juveniles emerge from the brood-pouch most commonly between nightfall and midnight and normal emergence seems to require diurnal alternation of light and dark. In continuous darkness, brood-pouch counts increased markedly, perhaps as a result of greater activity and feeding during darkness. Several features of the reproductive biology suggest that Melanoides might become a useful experimental animal in freshwater studies.