Role of salivary glands in the maintenance of midgut amylase activity inPeriplaneta americana L.

Summary It was experimentally demonstrated, by the surgical removal of salivary glands and severence of salivary ducts, that most of the amylase in the gut ofPeriplaneta americana comes from the salivary glands.We wish to acknowledge Prof. H. Swarup (Jiwaji University, Gwalior, M.P.) for working facilities provided at School of Studies in Zoology, Vikram University, Ujjain, M.P., and Council of Scientific and Industrial Research, New Delhi, for fincancial support in the form of Junior Research Fellowship to one of us (O.P.A.)     

Impairment of dendritic cells and adaptive immunity by anthrax lethal toxin

Anthrax poses a clear and present danger as an agent of biological terrorism. Infection with Bacillus anthracis, the causative agent of anthrax, if untreated can result in rampant bacteraemia, multisystem dysfunction and death. Anthrax lethal toxin (LT) is a critical virulence factor of B. anthracis, which occurs as a complex of protective antigen and lethal factor. Here we demonstrate that LT severely impairs the function of dendritic cells--which are pivotal to the establishment of immunity against pathogens--and host immune responses by disrupting the mitogen-activated protein (MAP) kinase intracellular signalling network. Dendritic cells exposed to LT and then stimulated with lipopolysaccharide do not upregulate co-stimulatory molecules, secrete greatly diminished amounts of proinflammatory cytokines, and do not effectively stimulate antigen-specific T cells in vivo. Furthermore, injections of LT induce a profound impairment of antigen-specific T- and B-cell immunity. These data suggest a role for LT in suppressing host immunity during B. anthracis infections, and represent an immune evasion strategy, where a microbe targets MAP kinases in dendritic cells to disarm the immune response.     

Enhancement of vertebrate cardiogenesis by a lectin from perivitelline fluid of horseshoe crab embryo

Cardiac myocytes are the first cells to differentiate during the development of a vertebrate embryo. A wide variety of molecules take part in various steps in this process. While exploring biologically active molecules from marine sources, we found that a constituent of perivitelline fluid from embryos of the Indian horseshoe crab can enhance growth and differentiation of chick embryonic heart. We have purified the factor and identified the cardiac promoting molecule to be a novel lectin. We show that this molecule influences cardiac development by increasing the number of cells constituting the heart and by modulating the expression of several cardiac development regulatory genes in chick embryos. Using mouse embryonic stem cells we show that the cardiac myocyte-enhancing capacity of this molecule extends to mammals and its effects can be blocked using methylated sugars. This molecule may prove to be an important tool in the study of cardiomyocyte differentiation.     

A luminous quasar at a redshift of z = 7.085

The intergalactic medium was not completely reionized until approximately a billion years after the Big Bang, as revealed by observations of quasars with redshifts of less than 6.5. It has been difficult to probe to higher redshifts, however, because quasars have historically been identified in optical surveys, which are insensitive to sources at redshifts exceeding 6.5. Here we report observations of a quasar (ULAS?J112001.48+064124.3) at a redshift of 7.085, which is 0.77 billion years after the Big Bang. ULAS?J1120+0641 has a luminosity of 6.3 × 10(13)L(⊙) and hosts a black hole with a mass of 2 × 10(9)M(⊙) (where L(⊙) and M(⊙) are the luminosity and mass of the Sun). The measured radius of the ionized near zone around ULAS?J1120+0641 is 1.9?megaparsecs, a factor of three smaller than is typical for quasars at redshifts between 6.0 and 6.4. The near-zone transmission profile is consistent with a Lyα damping wing, suggesting that the neutral fraction of the intergalactic medium in front of ULAS?J1120+0641 exceeded 0.1.     

Changes induced by manganese in fish testis

Summary Exposure ofColisa fasciatus, a freshwater teleost, to 2500 mg/l manganese sulphate for 90 h caused decreased spermatogenic activity and hemorrhage in the testes.     

A ratchet-like inter-subunit reorganization of the ribosome during translocation

The ribosome is a macromolecular assembly that is responsible for protein biosynthesis following genetic instructions in all organisms. It is composed of two unequal subunits: the smaller subunit binds messenger RNA and the anticodon end of transfer RNAs, and helps to decode the mRNA; and the larger subunit interacts with the amino-acid-carrying end of tRNAs and catalyses the formation of the peptide bonds. After peptide-bond formation, elongation factor G (EF-G) binds to the ribosome, triggering the translocation of peptidyl-tRNA from its aminoacyl site to the peptidyl site, and movement of mRNA by one codon. Here we analyse three-dimensional cryo-electron microscopy maps of the Escherichia coli 70S ribosome in various functional states, and show that both EF-G binding and subsequent GTP hydrolysis lead to ratchet-like rotations of the small 30S subunit relative to the large 50S subunit. Furthermore, our finding indicates a two-step mechanism of translocation: first, relative rotation of the subunits and opening of the mRNA channel following binding of GTP to EF-G; and second, advance of the mRNA/(tRNA)2 complex in the direction of the rotation of the 30S subunit, following GTP hydrolysis.     

Binding property of rat and Limulus C-reactive proteins (CRP) to mercury

The C-reactive proteins (CRP) from both rat and Limulus were found to bind mercury (Hg) in both in vivo and in vitro conditions. CRP has high-affinity binding sites for Hg as evidenced by the loss of free sulfhydryl groups, arrested mobility in polyacrylamide gel electrophoresis, and the consumption of CRP in the serum after Hg administration. The binding was tight as it could not be inhibited either by the addition of cysteine or EDTA. By using a direct titration method it was shown that binding of Hg to CRP was saturable at a molar ratio of Hg/CRP = 13.11. The possibility that CRP may act as a scavenger for Hg is discussed.     

Binding property of rat andLimulus C-reactive proteins (CRP) to mercury

Summary The C-reactive proteins (CRP) from both rat andLimulus were found to bind mercury (Hg) in both in vivo and in vitro conditions. CRP has high-affinity binding sites for Hg as evidenced by the loss of free sulfhydryl groups, arrested mobility in polyacrylamide gel electrophoresis, and the consumption of CRP in the serum after Hg administration. The binding was tight as it could not be inhibited either by the addition of cysteine or EDTA. By using a direct titration method it was shown that binding of Hg to CRP was saturable at a molar ratio of Hg/CRP=13.11. The possibility that CRP may act as a scavenger for Hg is discussed.     

低温合成活性羟基磷灰石和磷酸三钙

使用Ca(OH)2、H3PO4、CaF2为原始原料,根据羟基磷灰石和磷酸三钙的配比,设计了4个组成。先以溶胶-凝胶法制样,再用电炉在不同温度下煅烧,使其在低温下(900℃)合成无定形的、半结晶的、非化学计量的、活性的羟基磷灰石Ca5(PO4)3OH(HAP)和磷酸三钙β-3CaO·P2O5(β-C3P)。以XRD测试所形成的矿相,并对其可能的反应机理进行了探讨     

Phosphatase activity in testis and prostate of rats treated with embelin and Vinca rosea extract.

Daily administration of Vinca rosea Linn. extract orally and embelin s.c. to male albino rats caused significant rise in levels of acid and alkaline phosphatases of testis and prostate indicating altered metabolic function.