hsp 83 mutation is a dominant enhancer of lethality associated with absence of the non-protein codinghsrω locus inDrosophila melanogaster

Thehrsω or the 93D heat shock locus ofDrosophila melanogaster, which does not code for any protein, has an important role in development since nullosomy of this locus in transheterozygotes for two overlapping deficiencies, viz.,Df(3R) e ^Gp4 (eGp4) andDf(3R)GC14 (GC14), is known to cause a high (∼ 80%) mortality with the small number of escapee nullosomic flies being sterile, weak and surviving for only a few days. We now show that a majority of thehsrω-nulosomics die as embryo and that the 20% escapee embryos develop slower compared to their sibs carrying either one or two copies of thehsrω locus but after hatching survive to pupal/imago stage. Most interestingly, we further show that when onehsp83 mutant allele (hsp83 ^e4A) is introduced ineGp4/GC14 trans-heterozygotes, practically none of thehsrω-nullosomic embryos develop beyond the 1st instar larval stage. The specificity of this interaction betweenhsp83 andhsrω genes was further confirmed by examining the effect of thehsp83 mutant allele on other mutations in the 93D cytogenetic region. Therefore, we conclude that thehsp83 mutation acts as a dominant enhancer of the lethality associated with nullosomy for thehsrω gene. The observed genetic interaction between these two members of the heat shock gene family during normal embryonic development ofDrosophila reveals novel aspects of their biological functions.     

Cloning of acryIIIA endotoxin gene ofBacillus thuringiensis var.tenebrionis and its transient expression inindica rice

Damage caused to rice production by coleopteran insects like rice weevil (Sitophilus oryzae), a stored grain insect pest and rice hispa (Dicladispa armigera), a pest of the growing plant is quite high. In order to combat the damage, generation of insect resistant transgenic rice plant was considered desirable. CryIIIA endotoxin ofBacillus thuringiensis var.tenebrionis, a 65 kDa protein toxic to coleopteran insects, figured as the candidate gene product. Thus, the cryIIIA gene was isolated from a local isolate ofBacillus thuringiensis var.tenebrionis. The gene was tailored at the N-terminal end to its minimal size by using a synthetic ATG codon which replaced the first codon next to ATG of threonine to proline. This modification did not affect the functional property of the gene product. A chimeric construct of the modifiedcryIIIA gene was developed containing CaMV35S promoter andnos terminator for plant expression. The expressibility of thecryIIIA gene inindica rice was judged through test for transient expression in indica rice protoplasts.     

Evolutionary conservation of angiosperm flower development at the molecular and genetic levels

Flowers consist primarily of four basic organ types whose relative positions are universally conserved within the angiosperms. A model has been proposed to explain how a small number of regulatory genes, acting alone and in combination, specify floral organ identity. This model, known widely as the ABC model of flower development, is based on molecular generic experiments in two model organisms,Arabidopsis thaliana and Antirrhinum majus.Both of these species are considered to be eudicots, a clade within the angiosperms with a relatively conserved floral architecture. In this review, the application of the ABC model derived from studies of these typical eudicot species is considered with respect to angiosperms whose floral structure deviates from that of the eudicots. It is concluded that the model is universally applicable to the angiosperms as a whole, and the enormous diversity seen among angiosperms flowers is due to genetic pathways that are downstream, or independent, of the genetic programme that specifies floral organ identity.     

Photoinhibition of photosynthesis without net loss of photosystem II components inPopulus deltoides

The photoinhibition of photosynthesis was investigated on intact attached leaves and isolated thylakoid membranes of Populus deltoides.Our studies demonstrate that in intact leaves photoinhibition takes place under high irradiance which is more pronounced at higher temperatures. No net loss of Dl and other proteins associated with photosystem II (PSII) were observed even after 64 % photoinhibition suggesting that the degradation of polypeptides associated with PSII is not the only key step responsible for photoinhibition as observed by other workers. Electron transport studies in isolated thylakoid membranes suggested water oxidation complex as one of the damaged site during high light exposure. The possible mechanisms of photoinhibition without net loss of D1 protein are discussed.     

Follicular growth and kinetics in the Indian gerbil (Tatera indica) ovary during oestrous cycle

The growth of the follicle and oocyte in the Indian gerbil (Tatera indica) was a continuous process. The relationship between follicle and oocyte or its nucleus was log linear, represented by the equation log Y =a +b logX.A linear relationship (Y =a +bX)existed between the oocyte and its nucleus. The number of stages I and II follicles varied significantly during the oestrous cycle. Maximum percentage of stage I follicles was observed during oestrus and metoestrus, while stage II follicles were abundant during dioestrus, metoestrus and pro-oestrus. These follicles were significantly more in number than other types of the follicles. The occurrence of comparatively larger follicles during pro-oestrus and the presence of newly formed corpora lutea at oestrus, indicated ovulation in the early oestrus.     

Genome analysis of amaranths: Determination of inter- and intra-species variations

Amaranths are an important group of plants and include grain, vegetable and ornamental types. Despite the economic importance of the amaranths, there is very little information available about the extent and nature of genetic diversity present in the genus Amaranthus at molecular level. We now report the randomly amplified polymorphic DNA (RAPD) profiles of different species of Amaranthus as well as different accessions of the species. These RAPD analyses have been carried out using 65 arbitrary sequence decamer primers. From the RAPD data, an UPGMA dendrogram illustrating the inter-as well as intra-species relationships has been computed. The putative hybrid origin of A.dubious from A. hybridus and A. spinosus is also ruled out by the RAPD data. The trends of species relationships amongst the amaranths determined by RAPDs is consistent with their cytogenetic and evolutionary relationships that have already been determined. NBRI Communication No:464 (N.S.).     

A DNA fragment fromStreptomyces fradiae increases the production of a metalloprotease inStreptomyces lividans

Streptomyces fradiae produces several extracellular proteases and many of these are inducible. An 8.8 kb DNA fragment of Streptomyces fradiae cloned on pIJ699 caused increased protease activity in Streptomyces lividans.Clones carrying this recombinant plasmid showed a significant delay in sporulation. A protein of 18 kDa was purified from the extracellular proteins secreted by the host carrying the recombinant plasmid. Further characterization showed that this protease is a metalloprotease.     

Substances interfering with phosphatidyl inositol signalling pathway affect ultradian rhythm ofDesmodium motorium

The ultradian rhythm of the lateral leaflets ofDesmodium motorium}(Houtt.) Merril. was recorded with a picture analysis method using a video camera and a computer. The periods are in the minute range and depend strongly on temperature. The phosphatidyl inositol signal chain might be involved in the ultradian rhythm of the lateral leaflet movement of Desmodium motorium:Myoinositol shortens the period length and reduces the known period lengthening effect of lithium ions. Neomycin, which inhibits the hydrolysis of phosphatidylinositol-4,5 -biphosphate to inositol-4-phosphate and diacylglycerin, lengthens the period of the rhythm at low concentrations (0.2 mM). Higher concentrations shorten the period, perhaps by activating G protein. Mastoparan, which activates G protein, shortens period likewise. The G protein agonists fluorid ion and ethanol are toxic for the lateral leaflets and could therefore not be used to test the involvement of G protein. The intracellular Ca ²⁺ antagonist 3,4,5-trinietlioxybeiizoic acid 8-(diethylamino)octylester lengthens the period of the rhythm. This indicates, that release of Cas ²⁺ from intracellular stores is important for the lateral leaflet movement rhythm.     

Isolation and molecular characterization of theSinorhizobium meliloti bet locus encoding glycine betaine biosynthesis

To cope with osmotic stress,Sinorhizobium meliloti accumulates organic compatible solutes such as glutamate, trehalose, N-acetylglutaminylglutamine amide, and the most potent osmoprotectant glycine betaine. In order to study the regulation of the glycine betaine biosynthetic pathway, a genetic and molecular analysis was performed. We have selected a Tn5 mutant ofS. meliloti which was deficient in choline dehydrogenase activity. The mutation was complemented using a genomic bank ofS. meliloti. Subcloning and DNA sequencing of a 8-6 kb region from the complemented plasmid showed four open reading frames with an original structural organization of thebet locus compared to that described inE. coli. (i) ThebetB and thebetA genes which encode a glycine betaine aldehyde dehydrogenase, and a choline dehydrogenase, respectively, are separated from thebetI gene (regulatory protein) by an additional gene namedbetC. The BetC protein shares about 30% identity with various sulphatases and is involved in the conversion of choline-O-sulphate into choline. Choline-O-sulphate is used as an osmoprotectant, or as a carbon or sulphur source and this utilization is dependent on a functionalbet locus. (ii) No sequence homologous tobetT (encoding a high-affinity choline transport system inE. coli) was found in the vicinity of thebet locus. (iii) ThebetB and thebetA genes, as well as thebetI and thebetC genes are, respectively, separated by 211 and 167 bp sequences containing inverted repeats. Southern blot analysis indicated that thebet locus is located on the chromosome, and not on the megaplasmids.     

Adherence ofMycobacterium leprae to the nasal mucosa is influenced by surface integrity and viability

The intranasal route is one of the main routes of Mycobacterium leprae infection and there is paucity of information regarding the mode of spread of the pattern. The adherence of M.leprae to the nasal mucosa, its trapping within the sinuses of the head, and its fate after entry into the host was studied using mouse model. A comparison of the adherence profile of M. leprae and Mycobacterium tuberculosis showed that while larger numbers of M. tuberculosis were demonstrated within lungs, greater numbers of M.leprae were present within the sinuses of the head. Adherence of M.leprae to the nasal mucosa was dependent on surface integrity since opsonization and heat killing resulted in decreased numbers of M.leprae in the nasal sinuses and a greater amount entering the lungs. The adherence appeared to the independent of the viability of the bacilli, as similar numbers of formalin-fixed, rifampicin-treated and viable M.leprae entered the lungs in the initial stages. However the numbers of rifampicin-treated M. leprae in the nasal sinuses were 12-fold lower than the numbers of viable M.leprae. These results indicated that both viability and surface integrity were important in the entry of M.leprae and it’s consequent dissemination.     

Within- and among-population variation in oviposition preference for urea-supplemented food inDrosophila melanogaster

Oviposition preference for ureasupplemented food was assayed by simultaneous choice trials on five pairs of closely related laboratory populations of Drosophila melanogaster.Each pair of populations had been derived from a separate ancestral population about 85 generations prior to this study. One population in each pair had been subjected to selection for larval tolerance to the toxic effects of urea; the other population served as a control. Considerable variation in oviposition preference was seen both within and among populations, with four of the ten populations showing a significant mean preference for ureasupplemented food. The degree of specificity shown by individual females was surprisingly high, leading to a bimodal distribution of oviposition preference in some populations. Overall, selection for larval tolerance to urea did not significantly affect oviposition preference. However, the data indicated that pairwise comparisons between randomly selected populations from the two larval selection regimes would lead to a range of possible outcomes, suggesting, in several cases, that selection for larval urea tolerance had led to significant differentiation of adult oviposition preference for urea in one or the other direction. The results, therefore, highlight the importance of population level replication and caution against the practice, common in ecological studies, of assaying oviposition preference in two populations that utilize different hosts in nature, and then drawing broad evolutionary inferences from the results.     

Nitrate reductases inEscherichia coli

Escherichia coli expresses two different membrane-bound respiratory nitrate reductases, nitrate reductase A (NRA) and nitrate reductase Z (NRZ). In this review, we compare the genetic control, biochemical properties and regulation of these two closely related enzyme systems. The two enzymes are encoded by distinct operons located within two different loci on theE. coli chromosome. ThenarGHJI operon, encoding nitrate reductaseA, is located in thechlC locus at 27 minutes, along with several functionally related genes:narK, encoding a nitrate/nitrite antiporter, and thenarXL operon, encoding a nitrate-activated, two component regulatory system. ThenarZYWV operon, encoding nitrate reductase Z, is located in thechlZ locus located at 32.5 minutes, a region which includes anarK homologue,narU, but no apparent homologue to thenarXL operon. The two membrane-bound enzymes have similar structures and biochemical properties and are capable of reducing nitrate using normal physiological substrates. The homology of the amino acid sequences of the peptides encoded by the two operons is extremely high but the intergenic regions share no related sequences. The expression of both thenarGHJI operon and thenarK gene are positively regulated by two transacting factors Fnr and NarL-Phosphate, activated respectively by anaerobiosis and nitrate, while thenarZYWV operon and thenarU gene are constitutively expressed. Nitrate reductase A, which accounts for 98% of the nitrate reductase activity when fully induced, is clearly the major respiratory nitrate reductase inE. coli while the physiological role of the constitutively expressed nitrate reductase Z remains to be defined.Abbreviations NR nitrate reductase On leave from Department of Biochemistry and Molecular Biology, The University of Texas Medical school at Houston, Houston, Texas, 77225, USA     

Micropropagation of selected somaclones ofBegonia andSaintpaulia

Begonia x elatior plantlets which regenerated from leaf disk callus showed variations in plant morphology, number of flowers per plant, and flower size. Variations in flowering period, number of flowers per plant, and flower morphology were observed in Saintpaulia ionantha L. plants directly regenerated from leaf disk explants. The cytokinins, benzylaminopurine and zeatin, tested in the culture medium did not affect the basic plant characteristics including flower colour which remained stable in both species. Micropropagation of selected somaclones having the desirable trait of high number of flowers per plant was stable in the MV2 and MV3 generations.     

Mammotrope heterogeneity in the pituitary gland of European ferret,Mustela putorius furo: An immunoelectron-microscopic study

Employing the superimposition technique of electron-microscopic immunocytochemistry ultrastructural heterogeneity of the mammotropes in the pituitary gland of the European ferret,Mustela putorius furo,was studied. On the basis of the size of their secretory granules, the mammotropes were classified into three subtypes, type-I, type-II and type-Ill, which may correspond to different developmental or physiological states of a single cell type. Simultaneous study of mammotropes and somatotropes in several pairs of serial semithin sections demonstrated the occasional occurrence of bihormonal somatomammotropes /mammosomatotropes which may represent a transitional stage of the progenitor stem-somatotrope during its differentiation into mammotrope; alternatively it may be a functional intermediate during the cross-transformation of somatotrope into mammotrope or vice versa.     

Karyology of a few species of south Indian acridids. II Male germ line karyotypic instability inGastrimargus

Gastrimargus africanus orientalis,an acridid grasshopper has revealed the existence of karyotypic mosaicism in the male germ line cells of a few individuals with 2 n = 23, 19, 21, 25 and 27 chromosomes. Details of this chromosomal instability are presented in this paper. We dedicate this paper to our teacher Prof. L Siddaveere Gowda on the eve of his 60th birthday.     

三级综合医院护理人员安全文化认知现状调查

目的 描述和探讨三级综合医院的护理人员安全文化认知情况,为保障患者安全提出改进措施。方法 采用问卷调查法对1358名护理人员的安全文化认知情况进行调查和分析。结果 维度最高分为科室内团队合作（4.12±0.36）,积极反应率86.28%,维度沟通的公开性积极反应率最低,仅为36.28%。结论 临床护理人员在安全文化认知方面仍有待加强,人员配置及事故报告是构建安全文化的主要障碍,医疗机构应从系统角度出发,建立非惩罚性的事故报告制度,有效避免护患纠纷和安全事故的发生。     

Conformation of the C-terminal pentapeptide—the ‘message sequence’—of tachykinins as determined by consensus dynamic

The tachykinins are a family of gastrointestinal peptides comprising eight members: substance P, neurokinin A, neurokinin B, eledoisin, physalemin, uperolein, kassinin and phyllomedusin. Consensus dynamics was carried out on an ensemble of seven tachykinins to determine the binding conformation of the common C-terminal fragment: Phe-X-Gly-Leu-Met-NH ₂ ,the ’message sequence’ of tachykinins. Three binding modes for the C-terminal pentapeptide were determined. The first binding conformation is folded due to an intramolecular H-bond between the NH of the variable residue (X) and CO of Met. Other features include γ-bends at both the variable amino acid (X) and at Gly. The global minimum of the simulation has this conformation for the C-terminal pentapeptide. The other two binding modes have slightly higher energies. The second is chiefly characterized by a β-turn around the segment X-Gly-Leu-Met, with additional β-bends at the variable amino acid (X) and Met. The final binding conformation is composed of β-bends around the variable amino acid (X) and Leu, and a ’pseudo’ γ-bend at the terminal Met. This paper was presented at the MBU Silver Jubilee Symposium on Structural Biology and 24th Annual Meeting of the Indian Biophysical Society held at Indian Institute of Science, Bangalore, Dec. 9–12, 1996.     

Cloning of heterologous genes specifying detrimental proteins on pUC-derived plasmids inEscherichia coli

A system is described that enables the cloning of genes specifying detrimental proteins inEscherichia coli. The system is based on pUC plasmids and was developed for the expression of theBacillus subtilis csaA gene, which is lethal when expressed at high levels. Suppressor strains that tolerate the presence of plasmids for high-level expression ofcsaA were isolated, which contained small cryptic deletion variants of the parental plasmid in high copy numbers. The cryptic plasmids consisted mainly of the pUC replication functions and lacked thecsaA region and selectable markers. The co-resident, incompatible, cryptic plasmids enabled the maintenance of thecsaA plasmids by reducing their copy number 20-fold, which resulted in a concomitant 3- to 7-fold reduction in the expression of plasmid-encoded genes. Strains carrying these cryptic endogenous plasmids proved to be useful for the construction of pUC-based recombinant plasmids carrying other genes, such as theskc gene ofStreptococcus equisimilis, which cannot be cloned in high copy numbers inE. coli. Several strategies to reduce production levels of heterologous proteins specified by plasmids are compared.     

Determination and diagnostic value of CA9 mRNA in peripheral blood of patients with oral leukoplakia

Background: Oral leukoplakia is one of the most common oral premalignant disorder. The classical evaluation through tissue biopsy is not always valid to evaluate the risk of malignization.

Material and methods: RT-qPCR was performed on 47 blood samples (21 patients with leukoplakia, 2 with oral squamous cell carcinoma (OSCC), and 24 healthy patients) and on 11 tissue samples (3 leukoplakia, 4 OSCC, and 4 samples of healthy tissue).

Results: There are significant differences in expression between the different groups (F?=?4.057, p?=?.006). The Duncan post hoc test shows that the only group that differentiates is the tumour tissue. Using Wilcoxon test, different covariables of patients with leukoplakia were analysed with respect to the group of healthy patients and no significant differences were observed.

Conclusions: The diagnostic route through liquid biopsy has not been conclusive in this study, but there are significant differences in the levels analysed in the different tissue samples.     

TheisfA mutation inhibits mutator activity and processing of UmuD protein inEscherichia coli recA730 strains

Further studies on theisfA mutation responsible for anti-SOS and antimutagenic activities inEscherichia coli are described. We have previously shown that theisfA mutation inhibits mutagenesis and other SOS-dependent phenomena, possibly by interfering with RecA coprotease activity. TheisfA mutation has now been demonstrated also to suppress mutator activity inE. coli recA730 andrecA730 lexA51(Def) strains that constitutively express RecA coprotease activity. We further show that the antimutator activity of theisfA mutation is related to inhibition of RecA coprotease-dependent processing of UmuD. Expression of UmuD' from plasmid pGW2122 efficiently restores UV-induced mutagenesis in therecA730 isfA strain and partially restores its mutator activity. On the other hand, overproduction of UmuD'C proteins from pGW2123 plasmid markedly enhances UV sensitivity with no restoration of mutability.