Salt-stable association of simian virus 40 capsid with simian virus 40 DNA

In 8 M CsCl, a fraction of the wild-type previrions and tsB228 nucleoprotein complexes lose their core histones but retain their capsid. These histone-depleted complexes appear in the electron microscope as a protein shell attached to supercoiled DNA. Consistent with this result, we find that in 1 M NaCl, the wild-type previrions dissociate into two populations of nucleoprotein complexes. One population sediments between 50 and 140 S and morphologically resembles the shell-DNA complexes isolated in CsCl gradients. The other population is comprised primarily of nucleoproteins which sediment at 40 S.     

Cryptorchidism and Infertility in Rats with Targeted Disruption of the Adamts16 Locus

A Disintegrin And Metalloproteinase with ThromboSpondin motifs16 (ADAMTS-16) is a member of a family of metalloproteinases. Using a novel zinc-finger nuclease based gene-edited rat model harboring a targeted mutation of the Adamts16 locus, we previously reported this gene to be linked to blood pressure regulation. Here we document our observation with this model that Adamts16 is essential for normal development of the testis. Absence of Adamts16 in the homozygous Adamts16^mutant males resulted in cryptorchidism and male sterility. Heterozygous Adamts16^mutant males were normal, indicating that this is a recessive trait. Testes of homozygous Adamts16^mutant males were significantly smaller with significant histological changes associated with the lack of sperm production. Temporal histological assessments of the testis demonstrated that the seminiferous tubules did not support active spermatogenesis, but progressively lost germ cells, accumulated vacuoles and did not have any sperm. These observations, taken together with our previous report of renal abnormalities observed with the same Adamts16^mutant rats, suggest an important mechanistic link between Adamts16 and the functioning of the male genitourinary system.     

Correlation between dinucleotide periodicities and nucleosome positioning on mouse satellite DNA

Previous studies demonstrated 16 well-defined nucleosome locations (A-P) on a tandemly repeated prototype 234 base pair (bp) mouse satellite repeat unit. We have aligned the A-P fragments to search for DNA sequence elements that might contribute to nucleosome placement at these positions. Our results demonstrate a strikingly regular, uninterrupted, periodic pattern for the AA dinucleotide occurrences along the entire length of the aligned fragments. The periodicity of the AA occurrences is about 9.7 bp. The pattern exhibits a local minimum at position 74, near the nucleosome dyad axis of symmetry. Other dinucleotides--including AC: GT, CA: TG, and CC: GG--are also placed periodically, but their patterns of occurrence are less regular and less frequent than AA. The calculated spacings between consecutive preferred nucleosome locations on mouse satellite DNA are nearly identical, corresponding to multiples of 9.7 bp. The correlation between the periodicity of dinucleotide occurrences and the average spacing of nucleosome positions suggests that the preferred nucleosome locations recur at intervals that may correspond to the DNA helical repeat in the mouse satellite nucleosomes, and that the histone octamers sample (or slip along) the duplex in steps of 9.7 bp during nucleosome formation on mouse satellite DNA.     

New constituents from the dried fruit of Piper nigrum Linn., and their larvicidal potential against the Dengue vector mosquito Aedes aegypti

Six bioactive compounds were isolated from the seeds extract of Piper nigrum Linn. following a larvicidal activity guided isolation against 4th instar larvae of Aedes aegypti L., a Dengue vector mosquito and a carrier of yellow fever. Their structures were elucidated using spectroscopic methods including HR-EI-MS, FAB-MS, ¹H and ¹³C NMR (Broad Bond Decoupled, & DEPT), and 2D-NMR techniques (¹H–¹H COSY, NOESY, HMQC, HMBC, & 2D-J-resolved). These include three new constituents namely pipilyasine (1), pipzubedine (2) and pipyaqubine (3), and three known constituents pellitorine (4), pipericine (5) and piperine (6). The larvicidal activity was determined by WHO method.     

Simian Virus 40 Chromatin Interaction with the Capsid Proteins

Abstract

It has been established that both in virions and in infected cells, the cellular core histones fold the SV40 DNA into nucleosomes to form the SV40 chromosome or chromatin. We and others have begun to examine how the capsid proteins assemble the SV40 chromatin into virions and to investigate whether these proteins interact with the encapsidated chromatin. To follow the pathway of virus assembly, we have analyzed the nucleoproteins which accumulate in cells infected with the SV40 mutants temperature-sensitive in assembly: tsC, tsBC, and tsB. (The temperature-sensitivity of these mutants result from alterations in the amino acid sequence of the major capsid protein VP1). We have found that mutants belonging to the same class accumulate similar types of nucleoproteins at the nonpermissive temperature (40°C) and thus, share characteristics in common. For example, the tsC mutants accumulate only the 75 S chromatin. Both tsBC and tsB mutants produce in addition to chromatin, nucleoprotein complexes which sediment broadly from 100–160 S and contain all the three capsid proteins VP1, VP2, and VP3. These nucleoproteins can be distinguished morphologically, however. Under the electron microscope, the tsBC 100–160 S nucleoproteins appear as chromatin to which a small cluster of the capsid proteins is attached; the tsB nucleoproteins appear as partially assembled virions. In addition, we find that the 220 S virions are assembled in cells coinfected with tsB and tsC mutants at 40°C, in agreement with genetic analysis. Our observations favor the hypothesis that the VP1 protein contains three discrete domains. We speculate that each domain may play a specific function in SV40 assembly. To gain more insight into VP1-VP1 interactions, we have examined the nucleoproteins which result from treatment of the mature wild-type virions with increasing concentrations of the reducing agent DTT. In the presence of as low a concentration of DTT as 0.1 mM, the virion shell can be penetrated by micrococcal nuclease, which then cleaves the viral DNA. This result indicates that some of the disulfide bonds bridging the VP1 proteins are on the virion surface.     

Mitochondrial Dysfunction and Electron Transport Chain Complex Defect in a Rat Model of Tenofovir Disoproxil Fumarate Nephrotoxicity

The long‐term use of tenofovir, a commonly used anti‐HIV drug, can result in renal damage. The mechanism of tenofovir disoproxil fumarate (TDF) nephrotoxicity is not clear, although it has been shown to target proximal tubular mitochondria. In the present study, the effects of chronic TDF treatment on the proximal tubular function, renal mitochondrial function, and the activities of the electron transport chain (ETC) complexes were studied in rats. Damage to proximal tubular mitochondria and proximal tubular dysfunction was observed. The impaired mitochondrial function such as the respiratory control ratio, 2‐(4,5‐dimethyl‐2‐thiazolyl)‐3,5‐diphenyl‐2H‐tetrazolium bromide (MTT) reduction, and mitochondrial swelling was observed. The activities of the electron chain complexes I, II, IV, and V were decreased by 46%, 20%, 26%, and 21%, respectively, in the TDF‐treated rat kidneys. It is suggested that TDF induced proximal tubular mitochondrial dysfunction and ETC defects may impair ATP production, resulting in proximal tubular damage and dysfunction.     

Leishmanicidal Triterpenes from Lantana camara

Two new natural triterpenes, lantaninilic acid and lantoic acid, along with the known triterpenes lantadene A, and oleanolic, ursolic, betulinic, lantanolic, and camaric acid, were obtained from the aerial parts of Lantana camara through bioassay‐guided isolation, monitoring the in vitro antileishmanial activity against promastigotes of Leishmania major. Oleanolic acid ( 3 ), ursolic acid ( 4 ), lantadene A ( 5 ), and lantanilic acid ( 7 ) showed significant leishmanicidal activities with IC₅₀ values of 53.0, 12.4, 20.4, and 21.3 μM , respectively. The IC₅₀ value of ursolic acid ( 4 ; 12.4 μM ) was found to be comparable with that of the standard drugs, pentamidine (IC₅₀ 15.0 μM ) and amphotericin B (IC₅₀ 0.31 μM ). The in vitro activities of L. camara and its constituents against promastigotes of Leishmania major are reported here for the first time.