The

An 83-base-pair-long hepatitis B virus DNA fragment efficiently activates the transcription of the heterologous globin gene promoter. This fragment contains binding sites for at least four distinct cellular factors termed E, TGT3, EP, and NF-I. E is a positively acting factor, responsive to phorbol ester. EP is apparently identical to the factor EF-C that binds to the polyomavirus enhancer. The conservation of the binding site sequences for most of these factors in the genomes of other members of the hepadnavirus family suggests that these viruses share common enhancer elements.Human hepatitis B virus (HBV) is characterized by the mode of its replication which, unlike those of the other known DNA viruses, operates through reverse transcription of a pregenome RNA (7). The synthesis of pregenomic transcripts is therefore the crucial step in HBV replication. The elucidation of the regulation of HBV transcription is therefore of importance in understanding viral expression and replication. The first step along this line was the identification of an enhancer in the viral genome which regulates the expression of apparently all the viral promoters (6,20,21). To map the HBV enhancer in greater detail than done previously (20, 22), we have used a globin-based plasmid and assayed the enhancer activity by measuring the amount of globin mRNAs using the RNase A/T1 protection technique (12). An HBV DNA fragment (nucleotides 1043 to 1266), containing the enhancer, activated the ,-globin promoter in the transfected Alexander and HEp-3B cell lines (Fig. 1, fragment L). A shorter HBV fragment (fragment M) still exhibited enhancer activity, though to a lower extent. The level of enhancer activity was only slightly lower when a smaller fragment (fragment S) was inserted either at the 5' or at the 3' end of the ,-globin gene (Fig. 1). The S fragment contains the binding site of the nuclear protein previously designated by us as E (18).We have found that a single synthetic E site did not activate transcription (data not shown), suggesting that additional elements and trans-acting factors are required. In search of such factors, we fractionated nuclear extracts on a cation-exchange Bio-Rex 70 column (17). The fractions were analyzed by DNase I footprinting, using an end-labeled HBV probe that bears the sequence of the enhancer. At least three regions were protected by the 450 mM NaCl fraction; these were designated a, b, and EP (Fig. 2). An additional footprint, due to protection of the sequence TGTTT, was obtained in the 500 mM NaCl fraction and was termed accordingly TGT3. For reasons that are not clear to us the E footprint is missing in these fractionated extracts. Note, however, that the E and the EP sites are the only protected regions that were revealed when crude nuclear extracts were used (Fig. 2B). Since the TGT3 footprint overlaps with the lower portion of the E site, it is very likely that the E region is composed of two distinct recognition sequences. A simple way to test this possibility is to introduce a specific mutati...

The genetic structure of the cotton bollworm, Helicoverpa armigera (HuÈ bner) (Lepidoptera: Noctuidae), was studied in the eastern Mediterranean. Moths were sampled in six locations (®ve in Israel, and one in Turkey) and their genetic relationship was analysed using RAPD-PCR. Three 10-oligonucleotide primers revealed 84 presumptive polymorphic loci that were used to estimate population structure. Results reveal low level of genetic distances among Israeli and Turkish populations. The estimated values of F ST ST and h for the eastern Mediterranean populations were very low across all populations, indicating a high level of gene¯ow. Four distinct RAPD-product pro®le types were de®ned, and found in all Israeli and Turkish populations. Although no isolation by geographical distance was detected, topographical barriers may play a role in such isolation.

The hepatitis B virus (HBV) enhancer and the core gene promoter regulate the expression of the core and polymerase genes, as well as of the 3.5-kilobase pregenomic RNA. RNA analysis and chloramphenicol acetyltransferase gene expression by plasmids carrying the HBV enhancer linked to the heterologous ,-globin or simian virus 40 early promoter demonstrated that the HBV enhancer is 3to 20-fold preferentially expressed in human liver cells. Core gene promoter activity was mapped to a 100-base-pair fragment which was shown to be sufficient for accurate initiation of transcription. The partial tissue specificity of this promoter was demonstrated by transient transfection into various cell lines with a plasmid containing the core gene promoter linked to the heterologous simian virus 40 enhancer. When the HBV core gene promoter was examined under the control of the HBV enhancer, there was high tissue specificity in that activity could be observed only in differentiated human liver cells. These results suggest that the strict tissue specificity of HBV gene expression is determined by the combinatorial action of these two elements.

Production of males in uniparental lines of two species in the parasitic wasp genus Aphytis was induced by rifampicin, and male sexual functioning was determined. Wolbachia-specific 16S rDNA primers were used in a PCR in order to: (1) assess correlation between thelytokous reproduction and the presence of Wolbachia; (2) detect the loss of Wolbachia DNA in uniparental A. lingnanensis following antibiotic treatments, with or without the presence of a host; and (3) clone and sequence part of the Wolbachia 16S rDNA from the uniparental Aphytis species for phylogenetic studies. Males produced viable sperm that was transferred to the female spermatheca following mating. However, sperm failure to effect egg fertilization resulted in all-male progeny. Wolbachia were found in the two uniparental (A. lingnanensis and A. diaspidis) but not in the two biparental (A. lingnanensis and A. melinus) Aphytis lines tested. They can be detected in wasps up to 7 days following antibiotic treatments, regardless of the presence of host. The 16S rDNA for the symbionts in the two Aphytis species is virtually identical, and is most closely related to the Wolbachia found in Muscidifurax uniraptor (Pteromalidae).