Genetic mapping of a novel hypotrichosis locus to chromosome 7p21.3–p22.3 in a Pakistani family and screening of the candidate genes

Hereditary hypotrichosis is a heterogeneous group of inherited hair loss disorders characterized by diffused or localized thinning or absence of hair affecting scalp, eyebrows and eyelashes, and other body parts. Over the past few years, at least four autosomal dominant and six autosomal recessive forms of hypotrichosis have been described. All these ten forms of hypotrichosis have been mapped on different human chromosomes and the corresponding genes have been identified in most of these cases. In the present study, we have described a six-generation Pakistani consanguineous family with an autosomal recessive transmission of hereditary hypotrichosis. All the five affected individuals of the family showed complete absence of scalp hair and sparse eyebrows and eyelashes. They were born with complete absence of scalp hairs. Facial hair of beard and mustaches were present in all the affected adult male individuals. Papules were observed only on scalp of the affected individuals. A scalp biopsy from an affected individual showed markedly reduced number of hair follicles. Human genome scan using polymorphic microsatellite markers mapped the disease locus on chromosome 7p21.3–p22.3, flanked by markers D7S1532 and D7S3047. A maximum two-point LOD score of 4.74 (θ = 0.00) was obtained at marker D7S481. The linkage interval spans 15.69 cM, which corresponds to 6.59 Mb according to the sequence-based physical map (Build 36.2). Mutation analysis of five potential candidate genes (GNA12, FOXK1, DAGLB, ZNF12, ACTB), located in the linkage interval, did not reveal any functional sequence variant.     

A novel gene encoding a ras-like GTP-binding protein from Trypanosoma brucei: an evolutionary ancestor of the ras and rap genes of higher eukaryotes?

The ras superfamily of GTP binding proteins encompasses a wide range of family members, related by conserved amino-acid motifs, and act as molecular binary switches that play key roles in cellular processes. Gene duplication and divergence has been postulated as the mechanism by which such family members have evolved their specific functions. We have cloned and sequenced a ras-like gene, tbrlp, from the primitive eukaryote Trypanosoma brucei. The gene encodes a protein of 227 amino acids and contains the six conserved subdomains that designate it as a ras/rap subfamily member. However, the presence of key diagnostic residues characteristic of both the ras and rap families of GTP confuse the familial classification of this gene. Phylogenetic analysis of the GTP binding domain places its origins at the divergence point of the ras/rap families and suggests that tbrlp is an ancestral gene to the ras/rap genes of higher eukaryotes.     

Exploiting the wild crucifer <Emphasis Type="Italic">Thlaspi arvense</Emphasis> to identify conserved and novel genes expressed during a plant’s response to cold stress

Thlaspi arvense, a wild species from the Brassicaceae family, was shown to have a higher level of freezing tolerance than either of its close relatives, the model plant Arabidopsis thaliana or the crop Brassica napus (canola). Over 600 clones were sequenced from a subtractive cDNA library generated from cold treated T. arvense tissue, establishing that T. arvense shared significant sequence identity with both A. thaliana and B. napus (90–92%). In light of the strong sequence similarity between T. arvense and A. thaliana and to exploit the available genomics resources for Arabidopsis, the efficacy of using long 70 mer oligonucleotide whole genome Arabidopsis microarrays was tested for T. arvense. Gene expression in T. arvense leaf tissue during the very early stages of cold acclimation (or cold stress) was assayed at three time points and compared to an untreated control. This analysis highlights some of the difficulties and benefits of using cross-species microarray analysis. The data suggested that T. arvense responds in a similar fashion to cold stress as the model plant A. thaliana. However, for a number of genes quantitative differences in the level and timing of expression were identified. One of the most notable differences suggested that sulphur assimilation leading to the increased production of the methyl donor S-adenosyl-methionine was playing a role in the response of T. arvense to cold stress. Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users.     

Development of twelve novel polymorphic microsatellite DNA markers for the Boeseman’s rainbowfish (Melanotaenia boesemani) and tests for their cross-utility in 21 rainbowfish species from West Papua (Indonesia)

We developed 12 microsatellite markers for the endangered Boeseman’s rainbowfish (Melanotaenia boesemani). Twenty-eight individuals from the type locality at Ayamaru Lake were examined, and all loci were polymorphic with a number of alleles per locus varying from 3 to 18. Average observed and expected heterozygosities were 0.681 and 0.678, respectively. Cross-species amplification was successfully obtained for 21 Melanotaenia species, with a number of alleles per locus ranging between 1 and 20. Average observed and expected heterozygosities varied between 0.105 and 0.708 and 0.118–0.755, respectively. Only 21 inbreeding coefficient (Fis) values presented a significant homozygote excess among the 264 locus-by-locus calculated values. Tests for genotyping errors revealed that four of these 21 significant Fis values could be explained by the presence of null alleles. These new microsatellite markers appear highly reliable for further conservation purposes or population genetic studies of the many rainbowfish endangered species.