Portions of the central nervous system controlling reproductive behavior in Drosophila melanogaster

Drosophila melanogaster sex mosaics were tested in their courtship interactions with females and then with males. The distribution of genetically male and female tissues in each mosaic was determined with respect to an external cuticle marker and an internal enzyme marker. Performance of malelike courtship was correlated with the genotype of various tissues, with special attention being paid to the genotypes of head and thoracic ganglia. Male tissue in the left or right dorsal brain is necessary and nearly always sufficient to trigger early courtship actions--following of females and wing extension at them--but male tissue in both the dorsal brain and thoracic ganglia is necessary for attempted copulation to occur. Female tissue on or in the abdomen is nearly always necessary and sufficient for a mosaic to be courted by a male.

Liver regeneration in normal and alloxan-induced diabetic rats

The effects of alloxan-induced diabetes on liver regeneration were investigated. Normal and diabetic rats were sacrificed at eight time periods between 16 hours and 4 weeks following two-thirds partial hepatectomy or sham operation. The results indicate that alloxan-induced diabetes delays but does not prevent liver regeneration following partial hepatectomy. This delay is indicated by a depressed synthesis of RNA, DNA and protein during the first post-operative day and a lack of mitotic figures in the 24-hour sample. In addition, the synthesis of these three cellular constituents did not return to control levels as rapidly in the diabetics. Compared with the sham operated animals, the concentrations of total serum protein remained depressed longer in the diabetic hepatectomized animals. The data indicate that the metabolic alterations associated with alloxan diabetes delay the onset of the regenerative process and prolong the recovery period.

Renal blood flow autoregulation and renal venous prostaglandins in the pump-perfused canine kidney (in situ)

1. Renal autoregulation of blood flow was re-examined in the pump-perfused canine kidney and concentrations of prostaglandins E and F in the renal venous plasma were measured by radioimmunoassay. 2. At low perfusion pressures, below the range of autoregulation, prostaglandin E and F concentrations rose and calculated prostaglandin E secretion rate fell. 3. Meclofenamate (10 mg/kg i.v.) reduced renal blood flow and prostaglandin E and F secretion rates, but did not abolish autoregulation. 4. Renal prostaglandins do not appear to mediate autoregulation in the kidney but may affect the level at which flow is controlled.

Post-cholecystectomy wound morbidity: the influence of electrosurgery

The wound morbidity patterns following elective cholecystectomy were reviewed in 235 patients. The method used to divide the musculo-aponeurotic layers of the abdominal wall did not influence the overall wound morbidity rate. There was, however, a disproportionate number of males with wound morbidity following an electrosurgical incision. The explanation may be related to the increased rectus muscle mass in males.

Genetics of acetylcholinesterase in Drosophila melanogaster

Genes in Drosophila melanogaster that control acetylcholinesterase (AChE) were searched for by segmental aneuploidy techniques. Homogenates of flies containing duplications or deletions for different segments were assayed for enzyme activity. A region on the third chromosome was found for which flies having one dose consistently gave lower AChE activity than euploid flies, which in turn had lower activity than flies with three doses. The activity differences were in the approximate ratio 1:2:3. Fine structure deletion mapping within this region revealed a very small segment for which one-dose flies have approximately half-normal activity. To obtain putative AchE-null mutations, lethal mutations within this region were assayed. Four allelic lethals have approximately half-normal activity in heterozygous condition. These lethals probably define the structural locus (symbol: Ace) for AchE.

Chromosome segregation influenced by two alleles of the meiotic mutant c(3)G in Drosophila melanogaster

c(3)G is a gene in Drosophila melanogaster defined by two independently isolated mutants on the third chromosome. When homozygous in females, the mutants—c(3)G  17 or c(3)G  68—result in the elimination of meiotic crossing over and a great increase in nondisjunction at the first meiotic division. The gametic frequency of X-, second-, or third-chromosome nondisjunction is approximately .3 in c(3)G  17  , and .4 in c(3)G  68  ; for the fourth chromosome, the frequency is .2 in c(3)G  17 and .3 in c(3)G  68  . These values are at least two hundred fold greater than for spontaneous nondisjunction, though not high enough to indicate that chromosomes are distributed at random to the first meiotic division poles. Chromosomes loss is inferred from an excess of nullo-exceptional over diplo-exceptional ova. Loss is more frequent in c(3)G  68. If c(3)G females mate at low temperature, crossing over is still absent, but nondisjunction is decreased. c(3)G  17 is more temperature sensitive than c(3)G  68  .—Nonhomologous chromosomes tend to undergo nondisjunction in the same meiotic cells in c(3)G. Moreover, there is substantial nonhomologous pairing involving the larger chromosomes of the genome, inferred from the tendency for nonhomologs to disjoin from each other. Nonhomologous segregation is not observed between chromosome 4 and any other chromosome. c(3)G  68 exhibits more nonhomologous segregation than does c(3)G  17  , and, for either allele, the degree of nonhomologous segregation is directly proportional to the similarity in length of the two nonhomologs being considered. The degree of nonhomologous segregation is increased at low temperature.—Heterozygosity for inversions tends to increase c(3)G-mediated nondisjunction, and to alter the patterns of nonhomologous segregations. The effects are observed even if the inversion does not disrupt centromeric heterochromatin, and even though the inversions do not change the lengths of the chromosomes involved. In XXY females, c(3)G  17 shows more separation of the two X’s from the Y chromo-some than does c(3)G  68  . Fourth-chromosome nondisjunction is increased by the presence of a Y chromosome in both kinds of mutant females. But in XXY;c(3)G females which are also heterozygous for an X inversion, frequencies of fourth-chromosome nondisjunction are little different from those in XX; c(3)G females, while the degrees of XX-from-Y disjunction are increased.—The chromosome behavior of the two alleles of c(3)G is readily rationalized by a model which assumes that c(3)G+ controls a stage of meiosis prior to synapsis and crossing over. If exchange is directly disrupted in c(3)G homozygotes, disjunctional consequences should be the same in c(3)G  17 and c(3)G  68  . They are not. If, however, c(3)G+ controls a precondition to crossing over—such as the association of homologous and nonhomologous chromosomes—then the two alleles could each abolish crossing over, but lead to different amounts and patterns of nondisjunction.

Segmental aneuploidy and the genetic gross structure of the Drosophila genome

By combining elements of two Y-autosome translocations with displaced autosomal breakpoints, it is possible to produce zygotes heterozygous for a deficiency for the region between the breakpoints, and also, as a complementary product, zygotes carrying a duplication for precisely the same region. A set of Y-autosome translocations with appropriately positioned breakpoints, therefore, can in principle be used to generate a non-overlapping set of deficiencies and duplications for the entire autosomal complement.-Using this method, we have succeeded in examining segmental aneuploids for 85% of chromosomes 2 and 3 in order to assess the effects of aneuploidy and to determine the number and location of dosage-sensitive loci in the Drosophila genome (Figure 5). Combining our data with previously reported results on the synthesis of Drosophila aneuploids (see Lindsley and Grell 1968), the following generalities emerge.-1. The X chromosome contains no triplo-lethal loci, few or no haplo-lethal loci, at least seven Minute loci, one hyperploid-sensitive locus, and one locus that is both triplo-abnormal and haplo-abnormal. 2. Chromosome 2 contains no triplo-lethal loci, few or no haplo-lethal loci, at least 17 Minute loci, and at least four other haplo-abnormal loci. 3. Chromosome 3 contains one triplo-lethal locus that is also haplo-lethal, few or no other haplo-lethal loci, at least 16 Minute loci, and at least six other haplo-abnormal loci. 4. Chromosome 4 contains no triplo-lethal loci, no haplo-lethal loci, one Minute locus, and no other haplo-abnormal loci.-Thus, the Drosophila genome contains 57 loci, aneuploidy for which leads to a recognizable effect on the organism: one of these is triplo-lethal and haplo-lethal, one is triplo-abnormal and haplo-abnormal, one is hyperploid-sensitive, ten are haplo-abnormal, 41 are Minutes, and three are either haplo-lethals or Minutes. Because of the paucity of aneuploid-lethal loci, it may be concluded that the deleterious effects of aneuploidy are mostly the consequence of the additive effects of genes that are slightly sensitive to abnormal dosage. Moreover, except for the single triplo-lethal locus, the effects of hyperploidy are much less pronounced than those of the corresponding hypoploidy.