Wild-type Stocks Research Articles

Serotonin-immunoreactivity in the cerebellum of two neurological mutant mice and the corresponding wild-type genetic stocks

Using a serotonin (5-HT)-specific antibody, we examined the 5-HTergic innervation of the cerebellum in the normal mouse ( + + ) and in two neurological mutants: weaver ( wv/wv), which are characterized by a genetically determined loss of granule cells, and ‘Purkinje cell degeneration’ ( pcd/pcd), which are characterized by a genetically determined loss of Purkinje cells. In normal cerebellum, serotonin-immunoreactive (5-HT-ir) fibers are discrete and ascend to all three layers of the cerebellar cortex. Serotonin-immunoreactive fibers have a much higher density in the atrophic cerebella of both weaver and pcd mutants, where they form multidirectional contours. These anatomical findings provide a profile of 5-HT axon innervation of mouse cerebellum and extend previous neurochemical observations on the metabolic state of cerebellar 5-HT in neurological mutants.

The advantages that accrue to Drosophila melanogaster possessing larval serum protein 1

The survival and fecundity of wild-type Drosophila stocks and stocks lacking the major larval serum protein 1 were compared. Under laboratory conditions and under stress there was no significant difference between the survival of the two stocks. With respect to fecundity however, the wild-type stock was considerably superior, with the mutant stock being only 10% as fecund. This difference in fecundity is attributable to abnormal mating behaviour, a reduction in the number of eggs laid, a reduction in the number of eggs developing and severe abnormalities in the egg structure.

The abnormal oocyte phenotype is correlated with the presence of blood transposon in Drosophila melanogaster.

The abnormal oocyte mutation (2;44) originates in the wild: it confers no visible phenotype on homozygous abo males or females, but homozygous abo females produce defective eggs and the probability of their developing into adults is much lower than that of heterozygous sister females. We isolated by chromosome walking 200 kb of DNA from region 32. This paper reports that a restriction enzyme site polymorphism analysis in wild type and mutant stocks allowed us to identify a DNA rearrangement present only in stocks carrying the abo mutation. The rearrangement is caused by a DNA insert on the abo chromosome in region 32E which, by restriction map and sequence analysis, was identified as copia-like blood transposon. The transposon, in strains that had remained in abo homozygous conditions for several generations and had lost the abo maternal-effect, was no longer present in region 32E. Certain features of the abo mutation, discussed in the light of this finding, may be ascribed to the nature of the particular allele studied.

Genetic analysis of adult locomotor activity in Drosophila melanogaster

This study is an attempt to identify genes influencing spontaneous adult locomotor activity in Drosophila melanogaster. A wild type stock and 13 morphological marker stocks (six markers for chromosome X and seven for chromosome three have been used). Backcrosses have been set up to study linkage relationships between loci affecting the quantitative character and marker loci. The results suggest the presence of several genes influencing locomotor activity on both chromosomes analyzed.

Complementation of a Herpes Simplex Virus Type 1 Vmw110 Deletion Mutant by Human Cytomegalovirus

The herpes simplex virus type 1 (HSV-1) mutant dl1403 contains a 2 kb deletion within the sequences encoding the immediate early polypeptide Vmw110. Previous experiments showed that although dl1403 exhibits normal patterns of gene expression following infection at an m.o.i. of 5 p.f.u./cell its growth and plaquing efficiency are impaired in low multiplicity infections, particularly in human foetal lung (HFL) cells. We have now investigated the ability of two other human herpesviruses, varicella-zoster virus (VZV) and human cytomegalovirus (HCMV), to compensate for this defect at low m.o.i. in HFL cells. Co-infection with HCMV resulted in greatly increased plaque numbers and the apparent particle/p.f.u. ratios of dl1403 stocks were reduced to values similar to those exhibited by wild-type HSV-1 stocks. Complementation of dl1403 in low multiplicity infections by HCMV and VZV was also demonstrated by an increased yield of the mutant virus and an increase in synthesis of dl1403 DNA. Ultraviolet irradiation of HCMV abolished its ability to complement dl1403 and the presence of adenovirus 5 had no stimulatory effect on dl1403 DNA replication. When HFL monolayers were infected with dilutions of dl1403 stocks such that no plaques were produced, replication of the mutant virus could be induced by superinfection with HCMV 7 days after the initial infection. These results indicate that a non-lytic interaction between dl1403 and HFL cells is a more likely consequence of a low multiplicity infection than plaque formation.

Rare-male mating advantage in Drosophila ananassae

Summary - Minority-male mating advantage is a phenomenon whereby genetic variability can be maintained in populations without genetic load at equilibrium. Rare-male mating advantage has been shown to be a widespread phenomenon in Drosophila, although it is seen to be absent in some species. During the present investigation, experiments were conducted to study the mating success of wild type and mutant males at different ratios in the Elens-Wattiaux mating chamber using sepia and cardinal mutant stocks and a wildtype stock in order to detect a rare male effect in D. ananassae. In all the experiments the female-choice technique was employed. Red eye males were tested separately with sepia and cardinal mutants. Experiments were conducted at 9 different ratios. The results show that although both types of males are equally successful in mating when present in the same ratio, they are more successful in mating when in a minority. This advantage disappears when the males become common. Thus the present results provide evidence for the existence of a minority-male mating advantage in D. ananassae. Drosophila ananassae - sepia and cardinal mutants - rare male mating advantage

Plants regenerated from auxin-auxotrophic variants are inviable

Shoots regenerated from auxin-auxotrophic variants of Nicotiana plumbaginifolia were inviable when cultured in vitro in the absence of auxin. Variant shoots survived longer when grafted to wild-type stocks but eventually died after a characteristic pattern of degeneration. The auxin auxotrophs were isolated after mutagen treatment by a total isolation method as infrequent variants amongst haploid protoplast-derived cell colonies. The variants responded to several active auxins but, unlike the wild type, not to cytokinin. Plant regeneration from variant cultures ceased at early stages of shoot formation after complete withdrawal of auxin from the medium.

Phenotypic Expression of Wild-Type Tomato and Three Wilty Mutants in Relation to Abscisic Acid Accumulation in Roots and Leaflets of Reciprocal Grafts

Lycopersicon esculentum Mill. cv Rheinlands Ruhm (RR) and cv Moneymaker and the three wilty mutants flacca (flc), sitiens (sit), and sitiens(w) (sit(w)), together with most reciprocal grafts, were grown in pots and in solution culture. Detached leaflets, and control and steam-girdled intact plants, were left turgid or were wilted in air. Detached leaflets and the leaflets and roots of the intact plants were analyzed for their abscisic acid (ABA) content. Turgid RR leaflets contained about 2.9 ng ABA per milligram dry weight. On average, the flc and sit leaflets contained 33 and 11% of this amount, respectively. The lack of ABA approximately correlated with the severity of the mutant phenotype. Mutant roots also contained less ABA than wild-type roots. Wild-type scions on mutant stocks (wild type/mutant) maintained the normal phenotype of ungrafted plants. Mutant scions grafted onto wild-type stocks reverted to a near wild-type phenotype. After the wild-type leaves were excised from solution culture-grown mutant/wild-type plants, the revertive morphology of the mutant scions was maintained, although endogenous ABA levels in the leaflets fell to typical mutant levels and the leaflets became wilty again. When stressed in air, both leaflets and roots of RR plants produced stress-induced ABA, but the mutant leaflets and roots did not. The roots and leaflets of the grafted plants behaved according to their own genotype, with the notable exception of mutant roots grown with wild-type scions. Roots of flc and sit(w) recovered the ability to accumulate stress-induced ABA when grafted with RR scions before the stress was imposed.

Amplified ribosomal spacer sequence: Structure and evolutionary origin

A novel class of repeated sequences consisting of tandem arrays of ribosomal spacer sequence has been discovered in a mouse genome. Comparison to normal ribosomal DNA reveals that one repeat unit consists of two separate parts of spacer sequence. This amplified spacer sequence has a pseudogene-like structure but is distinct from the previously reported pseudogenes and orphons in regions lacking coding sequences. So far the amplified spacer sequence has been found only in the BALB/c mouse genome but not in ten other laboratory strains and several wild-type mouse stocks. Surprisingly, a part of the amplified spacer sequence unit had a higher homology to the corresponding part of the ribosomal DNA sequence of Mus musculus molossinus, a Japanese wild-type mouse, than to the corresponding part of the rDNA of the BALB/c mouse. These findings suggest that the amplified spacer sequence of the BALB/c mouse might have partly originated in M. m. molossinus or in a related subspecies.

A new enhancer locus, En(2)-hn, and a new allele of the enhancer, En(2)-cc, of male crossing over in Drosophila ananassae.

Genetic analyses were carried out using wild type stocks presumed to carry genetic components which strongly enhanced crossing over in males of Drosophila ananassae. A new enhancer (symbolized En(2)-cc) is located in the vicinity of the e locus residing in 2L of the E22 stock from India. This result suggests the possibility that the new enhancer and the En(2)-cm previously mapped to the right of the e locus in the L8 stock from Sri Lanka are allelic, although mapping lacks precision. Another new enhancer (symbolized En(2)- hn) discovered in the HW stock from Hawaii is identified to be situated in a new locus in the vicinity of the Arc locus in the proximal region of 2L. The En(2)-hn is separable from the En(2)-cm by recombination.

The distribution of and complementation relationships between spontaneous X-linked recessive lethal mutations recovered from crossing long-term laboratory stocks of Drosophila melanogaster

Males from a wild-type laboratory stock (M56i, Amherst), were mated with virgin females of the M-6 stock, In(1)sc 8 In(1)dl-49, y 31d sc 8 w a v Of f , and 149 spontaneous independent non-mosaically transmitted, as well as 8 incidentally detected, mosaically transmitted, X-linked recessive lethal mutations were recovered from 95704 F 2 cultures. 152 mutations were mapped over the entire length of the X-chromosome by complementation and/or crossover tests. Altogether 70 mutations, but no more than 63 mutations with lethal effects supposedly localized to single vital loci, fell into the 5 covered regions comprising about one-third of the X-chromosome that were studied in Lefevre's (1981) analysis of X-ray-induced lethal mutations. The distributions of spontaneous and X-ray mutations among the 5 regions were similar. Although there were far too few spontaneous mutations to make a meaningful comparison of relative mutability on a locus-by-locus basis, those loci displaying a relatively higher X-ray mutability, when taken as a group, tend to display a relatively higher spontaneous mutability, and those loci displaying a relatively lower X-ray mutability, when taken as a group, tend to display a relatively lower spontaneous mutability. Therefore, the data from lethal mutations are in agreement with the data from specific locus visible mutations and support the conclusion of Shukla et al. (1979) in being consistent with the assumption of proportionality between spontaneous and X-ray-induced mutation rates. Genetic analysis revealed that a minimum of 7.2% ( 11 152 ) of the were associated with chromosomal rearrangements. Within all covered regions, there were some 94 mutations that were tested for allelism, but only one possible case was found of a locus, l(1) L13, with as many as 3 independent intragenic mutations; it is unlikely that among the 152 mutations there were any other such loci. The locus most frequently involved in any kind of lethal mutation was the l(1) J1 locus near the distal tip of the X-chromosome with 5 mutations that included 3 ostensible multi-locus deficiencies. At equivalent entire X-chromosome recessive lethal mutation rates, the estimated per locus spontaneous mutation rate for non-mosaically transmitted X-chromosome lethals is about the same, or not lower than by a factor of 1 3 , as the estimated per locus spontaneous mutation rate for non-mosaically transmitted X-chromosome recessive visibles at 13 specific loci studies earlier by Schalet (1958, 1960) and re-evaluated here. In the earlier study of spontaneous visible mutations, at least 80% of the newly arisen non-clustered mutations (counting both transmitted and untransmitted), showed a mosaic distribution of mutant tissue by appearance and/or genetic test, but only 41% of the mutations that were germically completely mutant in transmission originally appeared in F 1 females as somatic mosaics. Upon reconsideration it is now appreciated that many newly arisen mutations would have been undetected because they were cryptic somatic mosaics. Accordingly, it is judged that the inclusion of an estimate of the numbers of undetected cryptic somatic mosaics would raise to at least 2 3 the proportion of newly arisen mutations that were somatic mosaics and germically complete in F 1 females. Among the 141 newly arisen non-clustered recessive lethal mutations that were germically complete, there were 9 mutations with dominant visible mutant effects and at least 3–5 of these were cryptic somatic or gonosomic mosaics. From the data on dominant and recessive visibles I infer that the majority of all spontaneous recessive lethal mutations were, although germinally complete, also mosaics of one type or another in F 1 females. Furthermore, if transposable elements were responsible for the mosaics observed or inferred to have occurred, then they must have been mobilized very early in cleavage in order to produce mutant cleavage nuclei more usually ancestral to somatic and germinal tissue or to somatic tissue alone, rather than germinal tissue alone.

Acquisition of incompatibility by inbred wild-type stocks of Mormoniella

Cross Incompatibility in Mormoniella is characterized by the absence of female progeny when certain stocks are crossed. First described 24 years ago, until recently it has been observed only in about nine stocks marked by R-locus eye color mutations. Recently, It has been found in four of the six wild-type stocks collected from natural populations and inbred in the Mormonlella Stock Center. The incompatibility was reciprocal, nonreclprocal, total, or partial depending on which stocks were crossed. Few mutant stocks maintained in the same laboratory have acquired the incompatibility.

Transmission and expression of mutations to nalidixic acid resistance among products of protoplast fusion crosses of Candida albicans

Earlier studies suggested that heritable resistance to nalidixic acid (Nal) induced in the asexual, pathogenic yeast Candida albicans by growth on Nal results from mitochondrial mutation. To determine conclusively whether mutations to Nal resistance are cytoplasmic or nuclear, several stable Nal-resistant (Nal r) mutants exhibiting distinctive differences in degrees of Nal resistance were obtained from each of two doubly auxotrophic strains (Ade −, Thr −, and Arg −, His −), both derived from the same wild-type stock. Inheritance of Nal resistance was then assessed in a series of protoplast fusion crosses between complementing auxotrophs. The initial, intact cellular products of a fusion cross are prototrophic heterokaryons which frequently assort single parental nuclei into monokaryotic blastospores containing biparental cytoplasms. Occasional karyogamy within heterokaryons also yields prototrophic hybrid monokaryons which can undergo recombinations for chromosomal markers through spontaneous or induced mitotic crossing-over. Segregation and expression of Nal resistance among non-hybrid, parental-type monokaryons from Nal r × Nal s heterokaryons showed that Nal r mutations are nuclear and that their expressions are not noticeably affected by admixture of cytoplasms of sensitive and resistant parental strains. Analyses of heterokaryons and hybrid monokaryons from Nal r × Nal s and Nal r × Nal r crosses demonstrated that Nal resistance is recessive to sensitivity, and that independent Nal r mutations arise at one gene in the Ade −, Thr − strain and at a separate, complementing single gene in the Arg −, His − strain. Prior work demonstrated that induction of Na r mutations in wild-type C. albicans depends profoundly on the (i) carbon and nitrogen nutrition, (ii) growth temperature, (iii) contact with particular metabolic inhibitors and (iv) division stage of cells during exposure to Nal. The present observations indicate that the character of cellular auxotrophies can determine the genetic loci at which Nal r mutations can be recovered.

Reduction of wild-typeXchromosomes with theYbb−chromosome ofDrosophila melanogaster

SUMMARYTheYbb−chromosome has been previously shown to induce reduction ofXchromosome ribosomal genes inXbb/Ybb−orXbb+/Ybb−flies. These reduction events are presumed to arise as one of the two products of unequal sister chromatid exchanges, which result in both magnified and reduced products. Bobbed reduced chromosomes may also arise as products of other recombinative events such as intrachromatid deletions. In this report we use theYbb−chromosome to reduce the number of ribosomal genes present onXchromosomes from two wild-type stocks under ‘non-magnifying’ conditions. We then show that the bobbed reducedXchromosomes show no detectable difference in their Southern blot rDNA patterns when compared with the parental wild-typeXchromosome. This indicates that reduction events do not preferentially delete certain repeat classes, and supports previous observations that the repeat types present in theD. melanogaster Xchromosome nucleolus organizer are not significantly clustered.

Studies on the Scutellar Bristles of Drosophila melanogaster. IV. Selection for Low Bristle Number in Oregon-RC Wild-type Lines

Results are presented of 130-145 generations of selection for low scutellar bristle number in four lines of D. melanogaster derived directly from an Oregon-RC wild-type stock and in one derived from an Oregon-RC line selected for low sternital bristle number. The most rapid initial response and the lowest mean scutellar bristle number ultimately reached, just below 2 bristles, occurred in a line in which the response was due to a new recessive gene located at approximately 17�4 on the X chromosome. Three of the other four lines reached a plateau just above a mean of 2 bristles after different patterns of response. These plateaux reflected a new canalization or threshold phenomenon at 2 bristles in these lines. The remaining line reached a mean of about 2� 5 bristles after some 50 generations and remained at that level or slightly higher thereafter, but had no indication of canalization at 2 bristles. Two relaxed lines were derived from each selection line at different times and showed variable patterns of regression towards the base population level.

The behavior during the initial phase of in vitro aggregation of dissociated imaginal disc cells from Drosophila melanogaster

Aspects of the initial phase of aggregation in vitro of dissociated imaginal disc cells from Drosophila melanogaster are described. Using the methods described certain interdisc differences in the percent decrease in single cell units during the first hour of aggregation can be demonstrated. In addition it is shown that prospective notum cells isolated from the dorsal mesothoracic disc show less of a decrease than do prospective wing cells. This difference shows up in a variety of different wild-type stocks and in several mutant stocks as well. Prospective notum cells from the mutation fu 59 show only a limited ability to adhere to one another, while the percentage of single cell units from prospective wing blade cells from r 9 larvae grown on pyrimidine-poor medium decrease less compared to cells from the same stock grown on RNA-supplemented medium. There is a significantly greater decrease in the percent single cell units in cultures of prospective eye cells than in cultures of prospective antennal cells. Furthermore, cells from the antennal disc of larvae bearing the homeotic mutation ss a show a significantly lower decrease in single cell units when grown at restrictive temperatures. In contrast, antennal disc cells from the homeotic mutation opthalmoptera; eyeless Dominant, a mutation which affects the eye disc, are unaffected, while cells from the eye disc are slightly less able to reassociate with one another.

MALE PHENOTYPES AND MATING EFFICIENCY IN CAENORHABDITIS ELEGANS

Mating behavior in adult male nematodes can be assayed by mating efficiency, i.e., the number of cross progeny sired by males under standard conditions. Mutant males from 220 strains, representing most of the known complementation groups of C. elegans, have been examined for mating efficiency and for anatomical abnormalities of the specialized male copulatory organs. These data extend the phenotypic description of these mutants and indicate what anatomical and behavioral components are necessary for the ability to mate successfully. Also, mutants with specific defects in the male were sought by establishing superficially wild-type hermaphrodite stocks after mutagenesis and testing the males segregated by these stocks for mating efficiency. Forty-nine of 1119 stocks yielded abnormal males. Seventeen were characterized in detail and found to be abnormal in sensory behavior (carrying mutations in the genes che-2 or che-3) or male genital anatomy (carrying mutations in one of the genes mab-1 to mab-10). Four of the mab (male abnormal) genes affect specific postembryonic cell lineages.

Characterization of the DNA of a Nonoccluded Baculovirus, Hz-1V

The DNA of the nonoccluded baculovirus (Hz-1V) obtained from the IMC-Hz-1 cell line was characterized by physicochemical and restriction endonuclease techniques. Hz-1V DNA isolated from purified virus had buoyant densities of 1.58 and 1.54 g/ml in CsCl-ethidium bromide density gradients, which corresponded to supercoiled and to relaxed circular and linear DNA, respectively. Neutral CsCl equilibrium centrifugation indicated that the Hz-1V DNA had a buoyant density of 1.7024 g/ml, which corresponded to a guanine-plus-cytosine (G+C) content of 43%. Thermal denaturation indicated a high G+C domain(s) in the Hz-1V genomic DNA. The domain(s), which included about 11% of the total genomic DNA, exhibited a T(m) of 97 degrees C. The remaining portion (89%) of the DNA had a T(m) of 86.5 degrees C. The T(m)s corresponded to G+C contents of 42 and 67%, respectively. The mean genetic complexity of Hz-1V DNA determined by DNA reassociation kinetic analysis was found to be 152 x 10(6). A possible rapidly reassociating component comprising approximately 13% of the genome was observed. The mean molecular weights from restriction endonuclease digests were 159 x 10(6) for both HindIII and EcoRI. Genomic heterogeneity was found in both the wild-type Hz-1V stock and in two plaque isolates. Of 12 single-plaque isolates, 3 basic restriction endonuclease DNA fragment patterns were observed. The molecular size estimates from electron microscopic contour lengths of uncloned viral DNA ranged from 70 to 158 megadaltons, and the mode was the 130- to 140-megadalton class.

SINGLE GENE CONTROL OF SEED COLOR AND HYPOCOTYL COLOR IN TURNIP RAPE

The association between hypocotyl color and seed color in turnip rape (Brassica campestris L.) was investigated in crosses of a green hypocotyl, yellow-seeded stock with an early flowering wild-type stock and the Torch cultivar. A complete association was noted between seed color and hypocotyl color. These data are consistent with the hypothesis that a single recessive gene may block pigment production in both hypocotyl and seed. The relevance of this information for breeding yellow-seeded turnip rape cultivars is discussed.

Genetic analysis of the larval secretion gene Sgs-4 and its regulatory chromosome sites in Drosophila melanogaster.

Larval salivary gland secretion from seven wild-type stocks of Drosophila melanogaster was electrophoretically analyzed. Considerable variability occurs in the X-chromosomally coded secretion protein 4, both qualitatively, as expressed by differences in electrophoretic mobilities, and quantitatively as seen by its relative amount in the secretion. Drosophila stocks with "normal" amounts of protein 4 show approximately 80-90% dosage compensation in the males, whereas in two stocks with lower amounts of protein 4 there is no indication of dosage compensation. Genetic analysis showed that the properties of secretion protein 4 and the level of expression of the Sgs-4 gene are controlled by the X-chromosome. Recombination experiments indicate that the stock-specific characteristics of protein 4 are properties of the structural gene Sgs-4 itself or of a chromosome region immediately adjacent to Sgs-4. One recombinant (R+79), manifesting an intermediate level of dosage compensation, indicates that a chromosome segment closely distal to Sg-4 is responsible for the regulation of the gene and for dosage compensation in particular. Accordingly, Sgs-4 must be transcribed from distal to proximal. Its position on the genetic map is 3.6. Two stocks, Hikone-R and Kochi-R, which were originally described as 0-mutants produce very low amounts of a specific secretion protein, 4 h, as revealed by a transvection effect and also by fluorography of overloaded gels.