Genetic and developmental factors in the olfactory response of Drosophila melanogaster larvae to alcohols.

Olfactory responses of Drosophila melanogaster larvae to a homologous series of primary alcohols (methanol ... decanol) were tested. Alcohols at either extreme of the chain lengths studied (methanol, ethanol and decanol) evoked no significant responses. Heptanol and nonanol both produced dose-independent responses, larvae being attracted to heptanol and repulsed by nonanol. The remaining alcohols elicited dose-related attractive responses. Responses to hexanol and nonanol decline with increasing larval age. Genetic differences were found for the response to heptanol, with larvae from a Japanese strain, Katsunuma, being indifferent to this substance. Chromosome exchange revealed that a major factor involved in the response to heptanol is located on chromosome II; factors on chromosome III quantitatively modulate this response. Three mutant strains were isolated following EMS mutagenesis of chromosome III. These three strains, IndifferentA, IndifferentB and IndifferentC, show incomplete or total anosmia when stimulated with nonanol. Adult flies from these strains show similar effects. IndifferenB and C strains are dominant over the Canton-S control strain; the IndifferentA strain shows semi-dominance. Results are discussed in the light of the ecology of Drosophila larvae and the relation between olfactory stimulus and receptor conformation and number.     

Adsorptive capacity of bacteriophage Mu on Escherichia coli K-12 strains with deletions in the attlambda region]

Escherichia coli strains with deletions in att lambda region were obtained. The comparison of the extent of deletions with the sensitivity of the corresponding mutant clones to phage Mu showed that the gene controlling the sensitivity of E. coli K-12 to the phage Mu is located in nad A-gal region of the bacterial chromosome. It is shown that the resistance of E. coli strains which had lost the region of bacterial chromosome between nad A gene and genes of gal-operon have adsorption character. Deletion of the nad A-gal region does not affect the adsorption of other phages (lambda, P1 and T4). Thus, the gene, located in this region, is responsible for the specific adsorption of the phage Mu.     

一份水稻矮杆小粒突变体的形态特征和基因定位

从水稻T-DNA插入突变体库中鉴定出一个矮杆小粒突变体t129,该突变体与野生型植株相比,植株明显矮化,籽粒粒长明显缩短,千粒重下降。遗传分析表明,t129的突变性状由一对隐性核基因控制,该基因(T129)经图位克隆定位于水稻第5染色体长臂上,引物InDel43和InDel57之间,物理距离为430 kb,并与标记InDel51共分离。本研究明确了该矮杆小粒突变体的表型特征及遗传规律,为进一步研究调控水稻株高和粒型基因奠定基础。     

莱菌（Chlamydomonas reinhardtii)subcbn I基因的遗传学性质分析

通过将莱茵衣藻回复合成叶绿素ｂ能力的１４种回复突变株和野生型杂文并对其后代进行四分子分析与随机分析,发现导致回复突变的抑制基因ｓｕｂ位于第一染色体,并根据其连锁程度的不同初步鉴定出５个同功能的非等位ｓｕｂ基因。杂交分析表明ｓｕｂ基因不具有等位专一性,以及在促使ｃｂｎＩ基因重新获得合成叶绿素ｂ的能力的过程中具有单一基因决定性状的特点,不同的ｓｕｂ基因具有其独立的表型效应。ｓｕｂ／Ｓｕｂ杂合二倍体的表型分析证明ｓｕｂ基因是显性突变基因。多个非等位ｓｕｂ基因的存在及其上述特点,都显示出叶绿素ｂ的生物合成,可能存在多种途径或多种调控方式。     

Isolation and characterization of Schizosaccharomyces pombe mutants defective in cell wall (1-3)beta-D-glucan.

Schizosaccharomyces pombe thermosensitive mutants requiring the presence of an osmotic stabilizer to survive and grow at a nonpermissive temperature were isolated. The mutants were genetically and biochemically characterized. In all of them, the phenotype segregated in Mendelian fashion as a single gene which coded for a recessive character. Fourteen loci were defined by complementation analysis. Studies of cell wall composition showed a reduction in the amount of cell wall beta-glucan in three strains (JCR1, JCR5, and JCR10) when growing at 37 degrees C. Galactomannan was diminished in two others. Strains JCR1 and JCR5, with mutant alleles cwg1-1 and cwg2-1, respectively, were further studied. The cwg1 locus was mapped on the right arm of chromosome III, 18.06 centimorgans (cM) to the left of the ade5 marker; cwg2 was located on the left arm of chromosome I, 34.6 cM away from the aro5 marker. (1-3)beta-D-Glucan synthase activities from cwg1-1 and cwg2-1 mutant strains grown at 37 degrees C were diminished, as measured in vitro, compared with the wild-type strain; however, Km values and activation by GTP were similar to the wild-type values. Mutant synthases behaved like the wild-type enzyme in terms of thermostability. Analyses of round shape, lytic behavior, and low (1-3)beta-D-glucan synthase activity in cultures derived from ascospores of the same tetrad showed cosegregation of all these characters. Detergent dissociation of (1-3)beta-D-glucan synthase into soluble and particulate fractions and subsequent reconstitution demonstrated that the cwg1-1 mutant was affected in the particulate fraction of the enzymatic activity while cwg2-1 was affected in the soluble component. The antifungal agents Papulacandin B and Aculeacin A had similar effects on the enzymatic activities of the wild type and the cwg2-1 mutant strain, whereas the cwg1-1 mutant, when growing at 37 degrees C, had a more inhibitor-resistant (1,3)beta-D-glucan synthase. It is concluded that the cwg1+ and cwg2+ genes are related to (1,3)beta-D-glucan biosynthesis.     

Nestmate recognition signals of the leaf-cutting ant Atta laevigata

Behavioral tests with field colonies of Atta laevigata were performed in order to identify the source of the odors used in nestmate recognition. We tested the postpharyngeal (PPG) and mandibular glands (MG) as putative organs producing chemical signals for nestmate recognition. Chemical analyses of PPG were also undertaken. With a series of bioassays, we confirmed that nestmate recognition is based on cephalic odors and that these odors come mainly from the mandibular gland secretion. We show chemical evidence that odors from MG are dispersed all over the cuticle. Although odors from PPG elicited colony-specific behavioral responses, the types of behaviors they elicited differed from those of nestmate recognition of whole ants or MG extracts. PPG secretion was characterized by long-chain alkanes and methyl branched alkanes of low volatility, whereas MG contained volatile ketones and alcohols.     

Genetic mapping of the chromosomal replication origin of Salmonella typhimurium.

Two hundred strains of Escherichia coli harboring Filv+ plasmids which carry a segment of the Salmonella typhimurium chromosome were isolated independently. Among them, two strains were found to harbor F' plasmids that are able to replicate in Hfr cells of E. coli; i.e., they carry a site designated poh (permissive on Hfr) of the S. typhimurium chromosome. The poh site is presumably identical with the replication origin (oriC) of the bacterial chromosome. These two plasmids carry the dnaA-uncA-rbs-ilv-cya-metE region of the chromosome of S. typhimurium. Other F' plasmids which only carried the ilv-cya-metE region were unable to be maintained in Hfr cells. The poh site (= oriC) of S. typhimurium thus is located in the uhp-ilv region of the chromosome. The two plasmids carrying the poh site of S. typhimurium can suppress the temperature-sensitive character of an E. coli mutant that carries the temperature-sensitive dnaA46 allele, when the plasmids exist in the mutant cells. This suggests that the dnaA chromosome in place of the dnaA gene product of E. coli itself. The ability of the plasmids carrying the poh site of S. typhimurium to replicate in Hfr cells of E. coli suggests that the replication system of E. coli can recognize the Salmonella replication origin.     

The paternal gene of the DDK syndrome maps to the Schlafen gene cluster on mouse chromosome 11

The DDK syndrome is an early embryonic lethal phenotype observed in crosses between females of the DDK inbred mouse strain and many non-DDK males. Lethality results from an incompatibility between a maternal DDK factor and a non-DDK paternal gene, both of which have been mapped to the Ovum mutant (Om) locus on mouse chromosome 11. Here we define a 465-kb candidate interval for the paternal gene by recombinant progeny testing. To further refine the candidate interval we determined whether males from 17 classical and wild-derived inbred strains are interfertile with DDK females. We conclude that the incompatible paternal allele arose in the Mus musculus domesticus lineage and that incompatible strains should share a common haplotype spanning the paternal gene. We tested for association between paternal allele compatibility/incompatibility and 167 genetic variants located in the candidate interval. Two diallelic SNPs, located in the Schlafen gene cluster, are completely predictive of the polar-lethal phenotype. These SNPs also predict the compatible or incompatible status of males of five additional strains.     

Sensitivity of a Salmonella typhimurium aspC mutant to sulfometuron methyl, a potent inhibitor of acetolactate synthase II.

Sulfometuron methyl is a potent and specific inhibitor of acetolactate synthase II in Salmonella typhimurium. Mutant strains sensitive to sulfometuron methyl on minimal medium were isolated following mutagenesis with Tn10. A conditionally auxotrophic insertion mutant, strain SMS409, which required aspartate at high temperatures or in the presence of tyrosine, was found among the 15 mutants isolated. The Tn10 insertion in strain SMS409 was mapped by conjugation and transduction to the region between aroA and pncB at 20 min on the chromosome of S. typhimurium; this location is similar to the genetic location of aspC in Escherichia coli. The specific activity of the aspC product, aspartate aminotransferase, was severely reduced in strain SMS409. This indicated that the Tn10 insertion in strain SMS409 inactivated aspC. An aspC mutant of E. coli was also inhibited by either sulfometuron methyl or tyrosine. We present a hypothesis which relates the observed alpha-ketobutyrate accumulation in sulfometuron methyl-inhibited cultures of strain SMS409 to aspartate starvation.     

Characterization of two polyketide methyltransferases involved in the biosynthesis of the antitumor drug mithramycin by Streptomyces argillaceus

A DNA chromosomal region of Streptomyces argillaceus ATCC 12596, the producer organism of the antitumor polyketide drug mithramycin, was cloned. Sequence analysis of this DNA region, located between four mithramycin glycosyltransferase genes, showed the presence of two genes (mtmMI and mtmMII) whose deduced products resembled S-adenosylmethionine-dependent methyltransferases. By independent insertional inactivation of both genes nonproducing mutants were generated that accumulated different mithramycin biosynthetic intermediates. The M3DeltaMI mutant (mtmMI-minus mutant) accumulated 4-demethylpremithramycinone (4-DPMC) which lacks the methyl groups at carbons 4 and 9. The M3DeltaM2 (mtmMII-minus mutant) accumulated 9-demethylpremithramycin A3 (9-DPMA3), premithramycin A1 (PMA1), and 7-demethylmithramycin, all of them containing the O-methyl group at C-4 and C-1', respectively, but lacking the methyl group at the aromatic position. Both genes were expressed in Streptomyces lividans TK21 under the control of the erythromycin resistance promoter (ermEp) of Saccharopolyspora erythraea. Cell-free extracts of these clones were precipitated with ammonium sulfate (90% saturation) and assayed for methylation activity using different mithramycin intermediates as substrates. Extracts of strains MJM1 (expressing the mtmMI gene) and MJM2 (expressing the mtmMII gene) catalyzed efficient transfer of tritium from [(3)H]S-adenosylmethionine into 4-DPMC and 9-DPMA3, respectively, being unable to methylate other intermediates at a detectable level. These results demonstrate that the mtmMI and mtmMII genes code for two S-adenosylmethionine-dependent methyltransferases responsible for the 4-O-methylation and 9-C-methylation steps of the biosynthetic precursors 4-DPMC and 9-DPMA3, respectively, of the antitumor drug mithramycin. A pathway is proposed for the last steps in the biosynthesis of mithramycin involving these methylation events.     

The total synthesis and characterization of six methyl branched isomers of 8,11,14-eicosatrienoic acid

Six methyl branched isomers of 8,11,14-eicosatrienoic acid were prepared in which a methyl branch was located on carbons 5, 10, 13, 17, 18 and 19. The     

黑腹果蝇中一个Cy染色体上的缺失

卷翅(Curly简称Cy)是易以识别的果蝇翅膀的显性突变, 是黑腹果蝇2号染色体上最常用的显性翅膀标记, 但对Cy的分子特征却不清楚。综合细胞遗传学与基因组学的信息,应用分子生物学技术,首次在Cy染色体上发现一个102 bp的缺失。该缺失存在于不同的卷翅品系中, 说明不同Cy染色体上存在某些共同的分子特征。同时以该缺失作为Cy染色体的DNA标记, 通过基因型多态分析, 初步证实Cy纯合型可导致果蝇胚胎期死亡。这些结果为进一步研究卷翅的分子遗传机理奠定了基础。     

SNP标记对角膜混浊小鼠 突变相关基因的精细定位

为深入研究前期工作中以ENU诱变技术建立的遗传性角膜混浊突变系小鼠(B6-Co)的遗传机制, 利用 SNP标记对其突变基因进行精细定位, 将该品系中具有角膜混浊表型的小鼠(B6-CoP)与DBA/2小鼠(简称D2)配种得到F₁代, 再回交D2亲本品系得到F₂代, 提取F₂代角膜混浊小鼠鼠尾DNA。在MGI数据库中选取小鼠13号染色体已定位区间附近5个在C57BL/6(简称B6)和D2两个品系之间有差异的SNP, 应用聚合酶链反应-限制性片段长度多态性(PCR-RFLP)技术及连锁分析方法对B6-Co小鼠突变基因进行精细定位。结果表明: B6-Co小鼠突变基因定位于13号染色体上112 546 283~113 397 654 bp之间, 因该区间内有5个已知基因, 其中Map3k1基因与小鼠眼睛形态生成和眼睑闭合密切相关, 提示Map3k1是B6-Co小鼠突变的强力候选基因。     

Isolation, characterization, and genetic analysis of monosomic, aneuploid mutants of Candida albicans

A white, prototrophic Candida albicans strain, heterozygous for the ADE2 gene (ade2/ADE2), was treated with the antimitotic agent methyl benzimidazole carbamate, and yielded red, adenine-requiring colonies at a rate of 4 x 10(-3), an order of magnitude higher than the spontaneous rate of Ade- colony formation. These red Ade- colonies were small, growing at approximately half the rate of the parent strain, and gave rise to large red colonies spontaneously. When the chromosomes of the small red colonies were separated by pulsed-field gel electrophoresis, the band hybridizing with the ADE2 gene was diminished in staining intensity by half relative to the parent and large red-colony strains. Restriction fragment-length polymorphism analysis and auxotrophic mutant spectra after mutagenesis suggested that the small red Ade- strains were monosomic aneuploids lacking one of a pair of chromosome homologues, while the large red strains had regained a homologue, presumably via a second non-disjunction event. Parasexual genetic analysis of two of the auxotrophs isolated from a putative aneuploid suggested that both mutations were linked to the ADE2 gene. These experiments suggest that targeted chromosome loss and monosomic, aneuploid strains have the potential to extend the scope of genetic analysis in this diploid, asexual organism.     

Land hermit crabs use odors of dead conspecifics to locate shells

A series of experiments at two tropical locations tested the ability of land hermit crabs Coenobita perlatus (H. Milne Edwards) and Coenobita compressas (H. Milne Edwards) to detect and respond to odors of dead conspecifics. An attraction array compared numbers of crabs attending hidden food odors and dead conspecific odors. Pit experiments tested crab shell-acquisition behaviors at different hidden odors. Bucket experiments confined crabs collected from various categories (feeding crabs, wandering crabs and crabs aggregated at dead conspecific odors) and tested behavioral responses to odors and an empty shell. Land hermit crab behavior at both sites was similar. Crabs were attracted to dead conspecific odors up to 10 times more than to food odors. Crabs attracted to dead conspecifics displayed significantly more shell-acquisition behaviors: touching other crab's shells in an exploratory manner and switching shells if an empty shell was available. In buckets, crabs from each category switched into shells. Results are compared to previous reports of similar shell-seeking behaviors by marine hermit crabs in response to dead conspecific odors. It is suggested that responding to dead conspecific odors for shell source location is an evolutionarily conserved behavior developed before hermit crabs became terrestrial.     

家蚕非滞育红卵突变体Re-nd突变基因的定位克隆

【目的】家蚕Bombyx mori非滞育红卵突变体Re-nd是唯一在非滞育状态下卵色呈现鲜红色的突变品种。本研究通过基因连锁分析和定位克隆的方法确定Re-nd的突变基因所在的染色体及紧密连锁位置,为后续Re-nd的功能研究及应用奠定基础。【方法】以家蚕卵色突变体Re-nd和野生型大造进行杂交,配制基因连锁分析群体材料和定位克隆群体材料;针对家蚕全染色体进行SNP标记开发,利用BC₁代群体材料进行基因连锁分析,确定Re-nd的突变基因所在的染色体;针对定位的Re nd的突变基因所在染色体进行SNP标记开发,利用BC₁群体材料对Re-nd的突变基因进行定位克隆。【结果】基因连锁分析结果显示Re-nd的突变表型与第6号染色体上的SNP标记完全连锁;初步定位克隆结果显示Re-nd的突变基因位于SNP标记SNP7和SNP17之间,物理距离4.04 Mb;以SNP7和SNP17之间筛选出的6个SNP标记和25个重组个体进行精细定位克隆,结果显示Re-nd的突变基因所在的区域位于SNP10和SNP12两个SNP标记之间的nscaf2853上,物理距离949.3 kb左右。【结论】将Re-nd的突变基因定位于第6号染色体的2个SNP标记SNP10和SNP12之间,物理距离约949.3 kb。本研究为后续Re-nd突变基因的精细定位及功能应用研究奠定了基础。     

Location of the recessive gene ym (yellow margin) on chromosome 12 of diploid Solatium tuberosum by means of trisomic analysis

Summary Ten out of twelve primary trisomics of dip-loid S. tuberosum were crossed as females with a recessive mutant for yellow margin (ym ym) obtained from S. phureja. All primary trisomics used proved to be homozygous dominant. Trisomic plants from all ten F₁'s were backcrossed with the mutant and trisomics from eight F₁'s were crossed also with a disomic heterozygous f₁ plant from triple 10 X mutant.In both BC₁ and half sib progeny of each trisomic type the mutant plants were easily identified because of their typical small roundish leaflets with yellow or reddish margins. The observed segregation ratios for normal to mutant were tested against the expected non-critical ratios and against various expected critical ratios.From the results of these tests it is concluded that the gene ym is located on chromosome 12 of the potato. A hypothesis of linkage between ym and a gene l _x for lethality is put forward. It is concluded that l _x is not identical with a previously detected recessive gene l ₂ which is responsible for yellow cotyledons and lethality.     

A large-scale screen for mutagen-sensitive loci in Drosophila

In a screen for new DNA repair mutants, we tested 6275 Drosophila strains bearing homozygous mutagenized autosomes (obtained from C. Zuker) for hypersensitivity to methyl methanesulfonate (MMS) and nitrogen mustard (HN2). Testing of 2585 second-chromosome lines resulted in the recovery of 18 mutants, 8 of which were alleles of known genes. The remaining 10 second-chromosome mutants were solely sensitive to MMS and define 8 new mutagen-sensitive genes (mus212-mus219). Testing of 3690 third chromosomes led to the identification of 60 third-chromosome mutants, 44 of which were alleles of known genes. The remaining 16 mutants define 14 new mutagen-sensitive genes (mus314-mus327). We have initiated efforts to identify these genes at the molecular level and report here the first two identified. The HN2-sensitive mus322 mutant defines the Drosophila ortholog of the yeast snm1 gene, and the MMS- and HN2-sensitive mus301 mutant defines the Drosophila ortholog of the human HEL308 gene. We have also identified a second-chromosome mutant, mus215(ZIII-2059), that uniformly reduces the frequency of meiotic recombination to <3% of that observed in wild type and thus defines a function required for both DNA repair and meiotic recombination. At least one allele of each new gene identified in this study is available at the Bloomington Stock Center.