Growth of macrophage-tropic and primary human immunodeficiency virus type 1 (HIV-1) isolates in a unique CD4+ T-cell clone (PM1): failure to downregulate CD4 and to interfere with cell-line-tropic HIV-1.

Human immunodeficiency virus type 1 (HIV-1) isolates derived directly from clinical samples are usually unable to grow in cytokine-independent continuous cell lines, thus hindering the study of their biological features and their sensitivity to humoral and cellular protective immunity. To overcome these limitations, we have derived from the Hut78 T-cell line a CD4+ clone (PM1) characterized by a unique susceptibility to a wide range of HIV-1 isolates, including primary and biologically pure macrophage (M phi)-tropic isolates (e.g., HIV-1BaL), which are unable to infect other human T- or promonocytic cell lines. Both primary and M phi-tropic HIV-1 establish persistent infection in PM1, with sustained levels of virus replication for prolonged periods. Experiments with chimeric viruses containing envelope fragments of HIV-1BAL inserted into the genetic framework of HXB2, a molecular clone derived from the cell-line-tropic isolate HIV-1IIIB, showed the third hypervariable domain (V3) of gp120 to be a critical determinant of the cell line tropism of HIV-1. Nevertheless, the V3 loop of HIV-1BaL was not sufficient to confer on the chimeras a bona fide M phi tropism. The biological characteristics of HIV-1BaL and of a primary isolate (HIV-1(573)) were investigated by using the PM1 clone. Infection of PM1 by HIV-1BaL was critically dependent on the CD4 receptor, as shown by competition experiments with an anti-CD4 monoclonal antibody (OKT4a) or with soluble CD4. However, the amount of soluble CD4 required for inhibition of HIV-1BaL was approximately 100-fold higher than for HIV-1IIIB, suggesting that the affinity of HIV-1BaL for CD4 is significantly lower. Infection of PM1 with either HIV-1BaL or HIV-1(573) failed to induce downregulation of surface CD4 expression and syncytium formation. Analogous results were obtained with a chimeric virus (HXB2[BaL PvuII-BamHI]) encompassing a large portion of gp120 and gp41 of HIV-1BaL, indicating that the env genes contain critical determinants for CD4 downregulation and syncytium formation. Consistent with the lack of CD4 downregulation, persistent infection of PM1 by HIV-1BaL or HIV-1(573) failed to interfere with HIV-1IIIB superinfection, as revealed by the expression of a type-specific V3 loop epitope (M77) and by the induction of extensive syncytium formation. This lack of interference suggests that a direct viral interaction may occur in vivo between biologically diverse HIV-1 strains.(ABSTRACT TRUNCATED AT 400 WORDS)     

Pholidota pygmaea (Orchidaceae) — A new species from Arunachal Pradesh, India

Chowdhery, H.J. & Pal, G.D. 1995. Pholidota pygmaea (Orchidaceae) — A new species from Arunachal Pradesh, India. — Nord. J. Bot. 15: 411–413. Copenhagen. ISSN 0107–055X.
A new species of Pholidota, P. pygmaea from Arunachal Pradesh, India is described.     

Evaluation of anti-tussive activity of Bergenia ciliata Sternb. rhizome extract in mice.

The methanol extract of the rhizome of Bergenia ciliata Sternb. (Saxifragaceae) has been evaluated for its potential in a cough model induced by sulphur dioxide gas in mice. The extract exhibited significant anti-tussive activity in a dose-dependent manner, as compared with control. The antitussive activity of the extract was comparable to that of codeine phosphate (10 mg/kg body wt.), a standard anti-tussive agent. The extract at doses of 100, 200 and 300 mg/kg body wt. (p.o.) showed significant inhibition of cough reflex by 28.7, 33.9 and 44.2%, respectively, within 90 min of the experiment.     

Anthelmintic efficacy of flemingia vestita (fabaceae): Genistein-induced alterations in the esterase activity in the cestode,raillietina echinobothrida

To ascertain the anthelmintic efficacy ofFlemingia vestita (an indigenous leguminous plant of Meghalaya, having putative anthelmintic usage), its crude root-tuber peel extract and active chemical principle, genistein, were testedin vitro with reference to esterase activity in the fowl tapeworm,Raillietina echinobothrida. With the localization of non-specific esterases (NSE) and cholinesterase (ChE), the organization of the cholinergic components of the nervous system in toto could be visualized in the cestodeo The specific ChE in the parasite is acetylcholinesterase (AChE). Both NSE and ChE were found in close association with the central and peripheral nervous components, besides being present in the tegument and muscular parts of the terminal male genitalia. The whole tissue homogenate of the parasite also showed a high AChE activity. After exposure to the crude peel extract (50 mg/ml of the incubation medium) and to genistein (0.5 mg/ml), a pronounced decline in the visible stain intensity in the cholinergic components of the nervous system and in the tegument was noticeable, indicating extremely reduced activity of NSE and ChE in these sites. The total AChE activity was also reduced to 4907% and 56–77%, following treatment with the peel extract and genistein, respectively. The reference drug, praziquantel (0.01 mg/ml) also caused reduction in the enzyme activity, somewhat at par with the genistein treatment. Genistein appears to have a transtegumental mode of action. Alteration in the AChE activity points towards acetylcholine, an inhibitory neurotransmitter in cestodes, as the potential target of action.     

The small,versatilepPZP family ofAgrobacterium binary vectors for plant transformation

The newpPZP Agrobacterium binary vectors are versatile, relatively small, stable and are fully sequenced. The vectors utilize the pTiT37 T-DNA border regions, the pBR322bom site for mobilization fromEscherichia coli toAgrobacterium, and the ColE1 and pVS1 plasmid origins for replication inE. coli and inAgrobacterium, respectively. Bacterial marker genes in the vectors confer resistance to chloramphenicol (pPZP100 series) or spectinomycin (pPZP200 series), allowing their use inAgrobacterium strains with different drug resistance markers. Plant marker genes in the binary vectors confer resistance to kanamycin or to gentamycin, and are adjacent to the left border (LB) of the transferred region. A lacZ -peptide, with the pUC18 multiple cloning site (MCS), lies between the plant marker gene and the right border (RB). Since the RB is transferred first, drug resistance is obtained only if the passenger gene is present in the transgenic plants.     

Escherichia coli exhibiting gram positivity after cetyl pyridinium chloride treatment

Summary Treatment with a solution of the detergent cetyl pyridinium chloride develops gram positivity in E. coli as is evident from the increased retention of crystal violet by the bacteria. Since cetyl pyridinium chloride has been found to remove larger quantity of lipid from E. coli than from the normal gram positive bacteria S. aureus, it is reasonable to think that lipid content in a bacteria may have an important role in determining the gram character of it. Gram negative bacteria generally contain more lipid than the gram positive ones.     

Diurnal and seasonal profiles of melatonin in the liver and their correlates of ovarian functions under natural photo-thermal conditions in adult carp Catla catla

Present study aimed to demonstrate daily rhythm features of hepatic melatonin concentrations in relation to ovarian functions during four reproductive phases of an annual cycle by measuring the levels of melatonin, 17-β estradiol (E2), vitellogenin (Vg) and maturation inducing hormone (MIH) in the liver and/or serum of adult carp Catla catla. Melatonin titres in liver, irrespective of reproductive phase, underwent daily variations with a peak in early dark phase and nadir at midday. However, the acrophase (Ø) of serum melatonin varied from late night in preparatory phase to midnight in the remaining parts of annual cycle. Their amplitude was highest during post-spawning phase and lowest during spawning phase. Hepatic E2 levels showed daily peak at midday and seasonal peak during pre-spawning phase. Though levels of serum Vg proteins and MIH did not exhibit daily variations, underwent seasonal changes with the highest and lowest values during spawning and post-spawning phases respectively. Hepatic melatonin titres always displayed significant negative correlation with the levels of both E2 and Vg. In essence, our study presented the first data on the daily and seasonal rhythm features of hepatic melatonin in carp and underlined their temporal relationship with the functions of ovary in any fish species.