Inheritance of 15 microsatellites in the Pacific oyster Crassostrea gigas:segregation and null allele identification for linkage analysis

Microsatellites were screened in a backcross family of the Pacific oyster, Crassostrea gigas. Fifteen microsatellite loci were distinguishable and polymorphic with 6 types of allele-combinations. Null alleles were detected in 46.7% of loci, accounting for 11.7% of the total alleles. Four loci did not segregate in Mendelian Ratios. Three linkage groups were identified among 7 of the 15 segregating loci. Fluorescence-based automated capillary electrophoresis (ABI 310 Genetic Analyzer) that used to detect the microsatellite loci, has been proved a fast, precise, and reliable method in microsatellite genotyping.

Electrophoretic Analysis of Isozymes and Discussion about Species Differentiation in Three Species of Genus Gymnocypris

By using the method of electrophoresis,three isozymes (lactate dehydrogenase,malate dehydrogenase and esterase) of three species of genus Gymnocypris were described and analyzed from North Tibet in this paper. The results showed that all three isozymes presented interspecific difference and distinct differentiation among individuals in the same population,and there was no electrophorectic difference between males and females. Analysis of relationships among three naked carps indicated a high degree of similarity between G. selincuoensis and G. cuoensis ,whereas low degree between G. selincuoensis and G. namensis . Furthermore,three isozymes presented expression of null alleles,and the duplicate genes of LDH A 2,LDH B 2,s MDH A 2 and m MDH B 2 also expressed in some individuals. Compared to other tetraploid fishes,three naked carps retained more functional duplicate genes and null alleles. This suggests fishes of genus Gymnocypris are at the early stage of evolution after polyploidization than that of fishes of Catostomidae,it directly related to the later time of schizothoracine fishes originate as well as severe environment.

Pseudohemophilia of Erik von Willebrand caused by homozygous one nucleotide deletion in exon 18 of the VW-factor gene

The original description of a novel severe bleeding disorder as"Hereditary Pseudohemophilia"by Erik von Willebrand can currently be labelled as von Willebrand disease(VWD)type 3.VWD type 3 is autosomal recessive caused by homozygous or double heterozygous null mutations in the von Willebrand factor(VWF)gene and typically characterized by prolonged bleeding time and APTT,FⅧ:C levels below 2%,undetectable VWF:Ag,VWF:RCo and VWF:CB and absence of ristocetin induced platelet aggregation(RIPA).Autosomal recessive von Willebrand disease type 3 VWD with virtual complete VWF deficiency are homozygous or compound heterozygous for two null alleles(gene deletions,stop codons,frame shift mutations,splice site mutations,and absence of m RNA).Reports on severerecessive VWD compound heterozygous for a null allele and a missense mutation and homozygous or double heterozygous for missense mutations are associated with very low but measurable FⅧand VWF:Ag and should be reclassified as severe recessive type 1 VWD.Homozygous missense or compound missense/null mutations related to recessive severe type 1 VWD have been indentified in the VWF prosequence D1 and D2domains,the D4,B1-3,C1-2 domains,and only a very few in the dimmerization site(D3 domain).The detection of even tiny amounts of VWF:Ag after desmopressin acetate(DDAVP)or in hidden sites like platelets allows the differentiation between patients with VWD type 3 and homozygous or double heterozygous recessive severe type 1.Carriers of a null allele related to VWD type 3 or a missense mutation related with severe recessive type 1 VWD may present with mild VWD with low penetrance of bleeding in particular when associated with blood group O.Heterozygous obligatory carriers(OC)of a null mutation or a missense mutation related to recessive VWD type 3 or severe type 1both present with asymptomatic or mild VWD type 1 in particular when associated with blood group O.The response to DDAVP of OC of either a nonsense or a missense mutation appears to be abnormal and diagnostic with a 3-times higher response of FⅧ:C as compared to VWF:Ag.In contrast,the responses to DDAVP of FⅧ:C and VWF:Ag are equally good in individuals with low VWF levels related to blood group O and a normal VWF gene and protein(pseudo-VWD).These observations are completely in line with and extend the original observations of von Willebrand in a large family with VWD type 3 and asymptomatic or mild true type1 VWD in OC.