Transfer of a marine DNA virus fromEctocarpus toFeldmannia (Ectocarpales,Phaeophyceae): aberrant symptoms and restitution of the host

Summary The marine brown algaEctocarpus siliculosus is invaded by a polyhedric virus, whose genome consists of circular, double-stranded DNA. In laboratory experiments this virus can infect a different host species,Feldmannia simplex. InfectedFeldmannia plants show severe somatic malformations. However, no functional virus particles are formed. SuchFeldmannia plants recover to resume a normal, symptom-free appearance. This result raises the possibility of intergeneric gene transfer in the natural habitat.     

在中国壮族家系中发现的一例-α~T/-α~Q复合β~0β~0珠蛋白基因型

本文报道在我国广西隆林壮族中发现一个罕見的HbQ复合α,β地中海贫血家系。先证者女,18岁,贫血面容,肝脾肿大。化学结构分析确证本Hb变异体为HbQ Thailand[α74(EF3)Asp→His]。血红蛋白组成以及α和β珠蛋白基因分析结果表明,先证者的珠蛋白基因型为-α~Q/-α~T复合β°/β°(IVSI-1G→T/Codon17A→T);先证者父的基因型为-‘α~Q/-复合β~O/β~A(IVSI-1G→T/β~A);先证母的基因型为-α~T/αα复合β~O/β~A(Codon17A→T/β~A)。     

RFLP tagging of a salt tolerance gene in rice

A salt tolerant rice mutant (M-20) was obtained through selection in vitro. Its tolerance was stably inherited over eight generations and most traints between M-20 and its sensitive original 77–170 (Oryza sativa) were very similar. By deriving an F₂ population of M-20 × 77–170 and splitting every F₂ individual into two parts, with one part planted in normal conditions and another part in saline conditions, the inheritance of salt tolerance in rice was studied. Under normal conditions, there was no apparent segregation among F₂ individuals. Under saline conditions, however, the segregation of traits was obvious. According to our standards, the ratio of salt sensitive:moderately-tolerant:tolerant plants was 25:42:18, in accordance with a 1:2:1 ratio. It suggested that the improvement of salt tolerance in our materials was induced by the mutation of a major tolerant gene which showed incomplete dominance. By use of 130 RFLP probes distributed throughout the rice genome, the gene was tagged by a single copy DNA probe, RG4, which was located on chromosome 7. The genetic distance between the salt tolerant gene and RG4 was 7.0 ± 2.9 cM. Based on the split method, a method which could be currently used to evaluate the damage of salt stress in rice was proposed.     

The UDP-Galactose:Ceramide Galactosyltransferase: Expression Pattern in Oligodendrocytes and Schwann Cells During Myelination and Substrate Preference for Hydroxyceramide

Abstract: Galactosylceramide ("galactocerebroside"; GalC) is a major glycolipid in the myelin sheath of the CNS and the PNS. The enzyme UDP-galactose:ceramide galactosyltransferase (CGalT) catalyzes the final step of the synthesis of GalC: the transfer of galactose to ceramide. By a differential screening approach, we have isolated a cDNA, the sequence of which is identical to the recently isolated cDNA clones for CGalT. By northern analysis and in situ hybridization we demonstrated that CGalT mRNA is expressed at birth in oligodendrocytes and Schwann cells, an expression pattern corresponding to the onset of myelination. In addition to the high expression levels of CGalT in oligodendrocytes and Schwann cells, in situ hybridization also showed expression in subtypes of neurons in spinal cord, cerebellum, and brainstem in the adult CNS, but at a much lower level than in oligodendrocytes. Expression of CGalT in COS cells demonstrated that CGalT has a preference for hydroxyceramide as a substrate. CGalT-expressing COS cells synthesize and transport GalC to their cell surface as shown by immunofluorescence and by lipid analysis of living cells. Our results suggested that the CGalT specifically uses hydroxyceramide for the synthesis of GalC and that separate (co)enzymes are not needed.     

Two-step regulation of ecdysone-inducible late puffs in salivary glands of Drosophila melanogaster

Our previous study showed that some ecdysone-inducible late puffs could also be induced by a mild detergent (digitonin) in Drosophila salivary glands. However, they could only be induced at the stage immediately prior to when developmentally programmed puffing occurred, suggesting that these late puff loci were under two-step regulation. Using an in vitro culture of salivary glands, we have examined whether ecdysone or the protein products of early puff genes participate in either of the two steps of late puff regulation. This study has revealed that (i) the acquisition of digitonin-responsiveness (the first step) could be induced in vitro by incubating salivary glands with ecdysone; (ii) the first step could also be induced by protein synthesis inhibition even in the absence of ecdysone; (iii) the second step required both ecdysone and protein synthesis unless treated with digitonin; and (iv) the first step, rather than the second step, determines the timing of normal puff formation in the loci. These results suggest that, during normal development, ecdysone controls both steps by activating two types of early genes; the first type, whose function can be mimicked by cycloheximide, renders the loci responsive to digitonin and the second type, whose function can be mimicked by digitonin, activates the loci to form puffs.