Ultrastructure and biochemical function of the mitochondria in respiratory-deficient mutant yeast induced by 4-nitroquinoline nitrogen oxide

1. A respiratory-deficient mutant strain of yeast was obtained from wild strain of Saccharomyces servisiae by treatment with 4-nitroquinoline N-oxide. Ultrastructure and function of the wild or mutant strains and the mitochondrial fractions isolated from these strains were examined by biochemical and electron microscopic analyses. 2. The frequency of the respiratory-deficient mutant strain in yeast induced with 10-6M 4-nitroquinoline N-oxide was about 40 %. 3. Respiratory-deficient mutant strain is incapable of reducing 2, 3, 5-triphenyltetrazolium chloride salt and to grow on lactate medium. In addition to this, the mutant has been found to have lost its ability to take up oxygen in sodium succinate and pyruvate. 4. 4.Nitroquinoline N-oxide in the concentration that induces a mutant of yeast cells or its kin inhibits the oxygen uptake in normal strain. 5. The normal strain of yeast is characterized by difference spectrum corresponding to cytochromes a+as, band c+Cll respectively, whereas, the mutant strain containes almost no cytochromes a+ as, band C1 but contains normal or increased amount of cytochrome c. 6. Mitochondrial fraction isolated from mutant strain has largely lost its ability to oxidize succinate. On the other hand, NADH-, lactate-and cytochrome c-oxidase activities are reduced by about 1/17, 1/7 and 1/8 of that of normal strain, respectively. 7. Succinate dehydrogenase activity of mutant strain is almost zero. Moreover, this activity is not affected on the addition of phenazine methosulfate. NADH dehydrogenase activity of mutant stran is about 1/2 of normal strain. 8. The variations in mitochondrial structure of normal and mutant strain in the stationary phase have been followed with the aid of electron microscopy. In contrast to the normal strain, the mutant strain revealed distinct morphological changes in mitochondria, especially, the lack of cristae in its interior. The results have been interpreted to indicate that the mutant induced by 4.nitroquinoline N.oxide has a character of cyto. plasmic mutant.</p

Evaluating Random Mutant Selection at Class-Level in Projects with Non-Adequate Test Suites

Mutation testing is a standard technique to evaluate the quality of a test suite. Due to its computationally intensive nature, many approaches have been proposed to make this technique feasible in real case scenarios. Among these approaches, uniform random mutant selection has been demonstrated to be simple and promising. However, works on this area analyze mutant samples at project level mainly on projects with adequate test suites. In this paper, we fill this lack of empirical validation by analyzing random mutant selection at class level on projects with non-adequate test suites. First, we show that uniform random mutant selection underachieves the expected results. Then, we propose a new approach named weighted random mutant selection which generates more representative mutant samples. Finally, we show that representative mutant samples are larger for projects with high test adequacy.Comment: EASE 2016, Article 11 , 10 page

A ClpB Chaperone Knockout Mutant of Mesorhizobium ciceri Shows a Delay in the Root Nodulation of Chickpea Plants

Several molecular chaperones are known to be involved in bacteria stress response. To investigate the role of chaperone ClpB in rhizobia stress tolerance as well as in the rhizobiaplant symbiosis process, the clpB gene from a chickpea microsymbiont, strain Mesorhizobium ciceri LMS-1, was identified and a knockout mutant was obtained. The ClpB knockout mutant was tested to several abiotic stresses, showing that it was unable to grow after a heat shock and it was more sensitive to acid shock than the wild-type strain. A plant-growth assay performed to evaluate the symbiotic performance of the clpB mutant showed a higher proportion of ineffective root nodules obtained with the mutant than with the wild-type strain. Nodulation kinetics analysis showed a 6- to 8-day delay in nodule appearance in plants inoculated with the Delta clpB mutant. Analysis of nodC gene expression showed lower levels of transcript in the Delta clpB mutant strain. Analysis of histological sections of nodules formed by the clpB mutant showed that most of the nodules presented a low number of bacteroids. No differences in the root infection abilities of green fluorescent protein tagged clpB mutant and wild-type strains were detected. To our knowledge, this is the first study that presents evidence of the involvement of the chaperone ClpB from rhizobia in the symbiotic nodulation process

Author Correction: A cell-free platform for the prenylation of natural products and application to cannabinoid production.

In the original version of this Article, the genotype of the M30 mutant presented in Fig. 3b was given incorrectly as Y288V/A232S, and the M31 mutant was given incorrectly as M1/A232S. The correct genotype of the M30 mutant is Y288A/A232S and for M31 it is Y288V/A232S. In addition, to keep consistency in genotype formatting, the genotype of the M27 mutant should be Y288V/G286S. The errors have been corrected in both the PDF and HTML versions of the Article

Mutant knots with symmetry

Mutant knots, in the sense of Conway, are known to share the same Homfly polynomial. Their 2-string satellites also share the same Homfly polynomial, but in general their m-string satellites can have different Homfly polynomials for m>2. We show that, under conditions of extra symmetry on the constituent 2-tangles, the directed m-string satellites of mutants share the same Homfly polynomial for m<6 in general, and for all choices of m when the satellite is based on a cable knot pattern. We give examples of mutants with extra symmetry whose Homfly polynomials of some 6-string satellites are different, by comparing their quantum sl(3) invariants.Comment: 15 page

Drosophila melanogaster mutant tan

Drosophila melanogaster gene tan was originally discovered in the early 20th century as a mutant strain lacking the dark pi gment pattern of wild-type (wt) f lies and, therefore, showing a light yellowish brown color (McEwen, 1918). Flies lack ing Tan function also exhibited abnormalities in vision (Benzer, 1967; Inoue et al. , 1988; True et al. , 2005), and tan males displayed an abnormal courtship behavior (Cook, 1980; Tomkins et al. , 1982). tan 1 ( t 1 ) and tan 3 ( t 3 ) alleles were found as spontaneous mutations, t 3 mutant being apparently lighter than t 1 (Brehme, 1941). tan is the structural gene for N- β -alanyldopamine hydrolase (NBAD-hydrolase or Tan protein), the enzyme that generates dopamine (DA) from NBAD (Wright, 1987; True et al. , 2005). Tan is expressed as a precursor protein of 43.7 kDa. Th is precursor is clea ved into two subunits of 29.9 and 13.8 kDa that apparently conform together a he terodimeric active protein (Wagner et al. , 2007). The enzyme that generates NBAD from DA, th e opposite reaction to the one catalyzed by Tan, is the NBAD-synthase or E bony protein (Wright, 1987; Pérez et al ., 1997), which is codified by the gene ebony . Since both Tan and Ebony ar e involved in cuticle tanni ng, carcinine re gulation, and NBAD metabolism in nervous tissue (Wright, 1987; Pérez et al. , 1997, 2004; Hovemann et al. , 1998; Borycz et al. , 2002; True et al. , 2005), it has been suggested that they function together in a system regulating the levels of dopamine during cuticle sclerotization a nd histamine in the visual metabolism (Borycz et al. , 2002; Pérez et al. , 2010). During the last few years, several publicati ons appeared regarding NBAD-synthase (Wappner et al ., 1996a, b; Pérez et al ., 1997, 2002, 2004, 2010; Hovemann et al. , 1998; Borycz et al. , 2002; Wittkopp et al., 2002; Schachter et al ., 2007), but very little is known about tan (True et al. , 2005; Wagner et al. , 2007). Thus, it was important to furthe r characterize the NBAD-hydrolase in D. melanogaster wt and in mutants t 1 and t 3.Fil: Badaracco, Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Quesada Allue, Luis Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Pérez, Martín Mariano. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales; Argentin

NHEJ protects mycobacteria in stationary phase against the harmful effects of desiccation

The physiological role of the non-homologous end-joining (NHEJ) pathway in the repair of DNA double-strand breaks (DSBs) was examined in Mycobacterium smegmatis using DNA repair mutants (DeltarecA, Deltaku, DeltaligD, Deltaku/ligD, DeltarecA/ku/ligD). Wild-type and mutant strains were exposed to a range of doses of ionizing radiation at specific points in their life-cycle. NHEJ-mutant strains (Deltaku, DeltaligD, Deltaku/ligD) were significantly more sensitive to ionizing radiation (IR) during stationary phase than wild-type M. smegmatis. However, there was little difference in IR sensitivity between NHEJ-mutant and wild-type strains in logarithmic phase. Similarly, NHEJ-mutant strains were more sensitive to prolonged desiccation than wild-type M. smegmatis. A DeltarecA mutant strain was more sensitive to desiccation and IR during both stationary and especially in logarithmic phase, compared to wild-type strain, but it was significantly less sensitive to IR than the DeltarecA/ku/ligD triple mutant during stationary phase. These data suggest that NHEJ and homologous recombination are the preferred DSB repair pathways employed by M. smegmatis during stationary and logarithmic phases, respectively

A dominant-negative FGF1 mutant (the R50E mutant) suppresses tumorigenesis and angiogenesis.

Fibroblast growth factor-1 (FGF1) and FGF2 play a critical role in angiogenesis, a formation of new blood vessels from existing blood vessels. Integrins are critically involved in FGF signaling through crosstalk. We previously reported that FGF1 directly binds to integrin αvβ3 and induces FGF receptor-1 (FGFR1)-FGF1-integrin αvβ3 ternary complex. We previously generated an integrin binding defective FGF1 mutant (Arg-50 to Glu, R50E). R50E is defective in inducing ternary complex formation, cell proliferation, and cell migration, and suppresses FGF signaling induced by WT FGF1 (a dominant-negative effect) in vitro. These findings suggest that FGFR and αvβ3 crosstalk through direct integrin binding to FGF, and that R50E acts as an antagonist to FGFR. We studied if R50E suppresses tumorigenesis and angiogenesis. Here we describe that R50E suppressed tumor growth in vivo while WT FGF1 enhanced it using cancer cells that stably express WT FGF1 or R50E. Since R50E did not affect proliferation of cancer cells in vitro, we hypothesized that R50E suppressed tumorigenesis indirectly through suppressing angiogenesis. We thus studied the effect of R50E on angiogenesis in several angiogenesis models. We found that excess R50E suppressed FGF1-induced migration and tube formation of endothelial cells, FGF1-induced angiogenesis in matrigel plug assays, and the outgrowth of cells in aorta ring assays. Excess R50E suppressed FGF1-induced angiogenesis in chick embryo chorioallantoic membrane (CAM) assays. Interestingly, excess R50E suppressed FGF2-induced angiogenesis in CAM assays as well, suggesting that R50E may uniquely suppress signaling from other members of the FGF family. Taken together, our results suggest that R50E suppresses angiogenesis induced by FGF1 or FGF2, and thereby indirectly suppresses tumorigenesis, in addition to its possible direct effect on tumor cell proliferation in vivo. We propose that R50E has potential as an anti-cancer and anti-angiogenesis therapeutic agent ("FGF1 decoy")