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1.
Genetic analysis of sterile mutants in the dpy-5 unc-13 (I) genomic region of Caenorhabditis elegans
Essential genes were identified in the 1.5-map unit dpy-5 unc-13 region of chromosome I in the Caenorhabditis elegans genome by rescuing lethal mutations using the duplication sDp2. In this paper, we report the mapping and complementation testing of lethal mutations, 45 of which identify 18 new, essential
genes. This analysis brings the number of essential genes defined by the sDp2 rescue of lethal mutants to 97; 64 of these map between dpy-5 and unc-13. 61% of these essential genes are identified by more than one allele. Positioning of the mutations was done using the breakpoints
of six duplications. The mutant phenotypes of 14 loci essential for fertility were characterized by Nomarski microscopy and
DAPI staining. None of the mutants were rescued by wild-type male sperm. The cytological data showed that four genes produced
mutants with defects in gonadogenesis, let-395, let-603, let-605 and let-610. Mutations in seven genes, let-355, let-367, let-384, let-513, let-544, let-545 and let-606, affected germ cell proliferation or gametogenesis. Mutants for the remaining three genes, let-370, let-599 and let-604, produced eggs that failed to develop or hatch, thereby acting as maternal effect lethals. We observed a nonrandom distribution
of arrest phenotypes with regard to map position.
Received: 8 May 1996 / Accepted : 27 January 1997 相似文献
2.
Nancy Garvey Evelyn M. Witkin Douglas E. Brash 《Molecular & general genetics : MGG》1989,219(3):359-364
Summary Ochre suppressor mutations induced by UV in the Escherichia coli glnU tRNA gene are CG to TA transitions at the first letter of the anticodon-encoding triplet, CAA. Premutational UV photoproducts at this site have long been known to exhibit an excision repair anomaly (mutation frequency decline or MFD), whereby post-irradiation inhibition of protein synthesis enhances their excision and reduces suppressor mutation yields ten-fold. We sought to clarify the basis of this unique repair response by determining the spectrum of UV photoproducts on both strands of a 36 by region of glnU which includes the anticodon-encoding triplet. We found that four different photolesions are produced within the 3 by sequence corresponding to the tRNA anticodon: (i) on the transcribed strand, TC (6–4) photoproducts and TC cyclobutane dimers are formed in equal numbers at the site of the C to T transition, indicating that this site is a hotspot for the usually less frequent (6–4) photoproduct; (ii) on the nontranscribed strand, TT dimers are found opposite the second and third letters of the anticodon-encoding triplet, adjacent to the mutation site; and (iii) on the nontranscribed strand, an alkali-sensitive lesion other than a (6–4) photoproduct is formed, apparently at the G in the mutation site. We suggest that mutation frequency decline may reflect excision repair activity at closely spaced UV lesions on opposite strands, resulting in double-strand breaks and the death of potential mutants. 相似文献
3.
An additive relationship of lethality between purified protease and haemolysin of the extracellular products (ECP) of Aeromonas salmonicida was demonstrated by i.p. injection in Atlantic salmon (Salmo salar L.). The lethal toxicity of the combinations of protease and haemolysin follow a linear regression line y = -54.54x + 2400. The LD50 of protease and haemolysin when injected separately was 2400 ng/g fish and 44 ng protein/g fish, respectively. 相似文献
4.
5.
Summary Thirty-three insertions of transposon Tn10l6l7 into genes involved in the control of rod cell shape were isolated in Salmonella typhimurium by the characteristic glossy appearance of colonies composed of spherical cells. Genetic tests demonstrated that 25 (76%) were insertions in the rodA gene, 7 (21 %) were mre mutants, and 1 (3%) was a divD mutant. No insertion in the pbpA gene were found. Insertions in cell shape genes only appeared when strains displaying resistance to mecillinam (not caused by -lactamase production) were employed. Neither rodA nor mre insertions could be transduced to wild-type strains but they were normally accepted by mecillinam-resistant derivatives and by cya and crp mutants, which, unlike the corresponding Escherichia coli strains, did not display resistance to mecillinam. On the other hand, the divD insertion could be efficiently transduced to any strain. It is concluded that the rodA, mre, and divD genes are involved in the control of rod cell shape but, in addition, the RodA and Mre products perform some function(s) that is essential for wild-type cells but dispensable for some mecillinam-resistant strains, and for cya and crp mutants. 相似文献
6.
J. A. Ampofo 《Biocontrol Science and Technology》1995,5(4):417-424
Locally available raw materials were used as fermentation media for the preparation of an effective bacterial insecticide of Bacillus sphaericus in Ghana. The choice of materials for media production was based on their availability, their cost and how well they supported growth and sporulation of the bacterium. The materials used were anchovy (Engraulis encrasicolus), spent grain from breweries, bambara beans (Vigna subterranea), sprout maize (Zea mays) and B. sphaericus strain IAB 881. The larvicidal activities of each final whole culture of the insecticides prepared were evaluated against third and fourth instar larvae of the mosquito species Culex quinquefasciatus. The levels of larvicidal activity exhibited by preparations using the raw materials were similar to those where the bacterium was cultured in a synthetic medium, with median lethal concentrations ranging from 0.30 10- 5 to 0.68 10-6. Cell counts were in the range 11 108 - 36 108 colony-forming units ml-1, and spore counts were between 29 107 and 61 107 ml-1. 相似文献
7.
Isolation and characterization of pock-forming plasmids for Streptomyces griseus from soil actinomycetes 总被引:3,自引:0,他引:3
Thirty independent actinomycetes strains carrying plasmids were isolated from soil. These plasmids were purified as cccDNA by CsCl-EtBr equilibrium density-gradient centrifugation. Plasmids that induce "pocks", namely formation of circular zones of sporulation-inhibition, were selected by protoplast transformation of streptomycin-producing strain, Streptomyces griseus ATCC10137. Six pock-forming plasmids, pOA7, pOA11, pOA15, pOA23, pOA29 and pOA30, were obtained, and their cleavage maps, transformation frequencies, and copy numbers, as well as their stability, are described. 相似文献
8.
A.M. Luke R. Patnaik S.T. Kuriadom M. Jaber S. Mathew 《Saudi Journal of Biological Sciences》2021,28(1):887
Oral squamous cell carcinoma (OSCC) is the most commom cancer in the world. If remain untreated for several years, it may be fatal. Hence, it is important to prevent and treat OSCC at an early stage. In this study the effect of aqueous and dry leaves extract of Ocimum sanctum was observed on Ca9-22 cell line, which is an OSCC cell line. For this, Ca9-22 cell line was cultured and maintained. After 24 h, the cells were treated with aqueous and dry leaves extract of Ocimum sanctum plant. Viability of the cancerous cells were studied by 3-(4, 5-dimethythiazol-2-yl)-2, 5-diphenyl tetrazolium bromide (MTT) assay and neutral red uptake (NRU) assay. Minimum inhibitory concentrations (MIC), lethal concentration25 (LC25), lethal concentration50 (LC50) and highest permissive concentration (HPC) was calculated by probit computational method. Experimentally, the MIC value was 5 mg/L, whereas the HPC was 30 mg/L of the plant extract in aqueous state. For the dry extract the MIC was 5 mg/L whereas the HPC was 35 mg/L for both MTT and NRU assays. For MTT assay LC values: 7.41 (LC25), 14.79 (LC50) and 26.91 mg/L (LC75) for aqueous extract and 12.58 (LC25), 20.89 (LC50), 29.51 mg/L (LC75) for dry extract. For NRU assay LC values were 10.23 (LC25), 14.79 (LC50) and 20.89 mg/L (LC75) aqueous extract, and 16.59 (LC25), 23.44 (LC50), 30.19 mg/L (LC75) dry extract of the plant. From the above study it was concluded that, Ocimum sanctum have anti-cancerous activity. It can further be used for therapeutic purposes. 相似文献
9.
《Cell Adhesion & Migration》2013,7(4):378-383
Cell migration is a highly integrated, multistep process that plays an important role in physiological and pathological processes. The migrating cell is highly polarized, with complex regulatory pathways that integrate its component processes spatially and temporally.1 The Drosophila tumor suppressor, Lethal (2) giant larvae (Lgl), regulates apical-basal polarity in epithelia and asymmetric cell division.2 But little is known about the role of Lgl in establishing cell polarity in migrating cells. Recently, we showed that the mammalian Lgl1 interacts directly with non-muscle myosin IIA (NMIIA), inhibiting its ability to assemble into filaments in vitro.3 Lgl1 also regulates the cellular localization of NMIIA, the maturation of focal adhesions, and cell migration.3 We further showed that phosphorylation of Lgl1 by aPKCζ prevents its interaction with NMIIA and is important for Lgl1 and acto-NMII cytoskeleton cellular organization.4 Lgl is a critical downstream target of the Par6-aPKC cell polarity complex; we showed that Lgl1 forms two distinct complexes in vivo, Lgl1-NMIIA and Lgl1-Par6-aPKCζ in different cellular compartments.4 We further showed that aPKCζ and NMIIA compete to bind directly to Lgl1 through the same domain. These data provide new insights into the role of Lgl1, NMIIA, and Par6-aPKCζ in establishing front-rear polarity in migrating cells. In this commentary, I discuss the role of Lgl1 in the regulation of the acto-NMII cytoskeleton and its regulation by the Par6-aPKCζ polarity complex, and how Lgl1 activity may contribute to the establishment of front-rear polarity in migrating cells. 相似文献
10.
Jeyoun Jang Minhui Cho Hae-Ri Lee Kiweon Cha Jeong-Hoon Chun Kee-Jong Hong Jungchan Park Gi-eun Rhie 《Biochimica et Biophysica Acta (BBA)/General Subjects》2013