scholarly journals Revisiting suppression of interspecies hybrid male lethality in Caenorhabditis nematodes

2017 ◽  
Author(s):  
Lauren E. Ryan ◽  
Eric S. Haag
Keyword(s):  
Rna Interference ◽  
Sex Ratio ◽  
Related Species ◽  
Wild Type ◽  
Hybrid Male ◽  
Female Progeny ◽  
Closely Related Species ◽  
Interspecies Hybrids ◽  
Biased Sex Ratio ◽  
Interspecies Hybrid

AbstractWithin the nematode genus Caenorhabditis, C. briggsae and C. nigoni are among the most closely related species known. They differ in sexual mode, with C. nigoni retaining the ancestral XO male-XX female outcrossing system, while C. briggsae females recently evolved self-fertility and an XX-biased sex ratio. Wild-type C. briggsae and C. nigoni can produce fertile hybrid XX female progeny, but XO progeny are either 100% inviable (when C. briggsae is the mother) or viable but sterile (when C. nigoni is the mother). A recent study provided evidence suggesting that loss of the Cbr-him-8 meiotic regulator in C. briggsae hermaphrodites allowed them to produce viable and fertile hybrid XO male progeny when mated to C. nigoni. Because such males would be useful for a variety of genetic experiments, we sought to verify this result. Preliminary crosses with wild-type C. briggsae hermaphrodites occasionally produced fertile males, but they could not be confirmed to be interspecies hybrids. Using an RNA interference protocol that eliminates any possibility of self-progeny in Cbr-him-8 hermaphrodites, we find sterile males bearing the C. nigoni X chromosome, but no fertile males bearing the C. briggsae X, as in wild-type crosses. Our results suggest that the apparent rescue of XO hybrid viability and fertility is due to incomplete purging of self-sperm prior to mating.

Genetic Complexity Underlying Hybrid Male Sterility in Drosophila

Genetics ◽  
2004 ◽  
Vol 166 (2) ◽  
pp. 789-796 ◽  
Author(s):  
Kyoichi Sawamura ◽  
John Roote ◽  
Chung-I Wu ◽  
Masa-Toshi Yamamoto
Keyword(s):  
Male Sterility ◽  
Related Species ◽  
Synergistic Effects ◽  
Female Sterility ◽  
Hybrid Male ◽  
Hybrid Female ◽  
Hybrid Male Sterility ◽  
Closely Related Species ◽  
Genetic Complexity ◽  
Recessive Genes

Abstract Recent genetic analyses of closely related species of Drosophila have indicated that hybrid male sterility is the consequence of highly complex synergistic effects among multiple genes, both conspecific and heterospecific. On the contrary, much evidence suggests the presence of major genes causing hybrid female sterility and inviability in the less-related species, D. melanogaster and D. simulans. Does this contrast reflect the genetic distance between species? Or, generally, is the genetic basis of hybrid male sterility more complex than that of hybrid female sterility and inviability? To clarify this point, the D. simulans introgression of the cytological region 34D-36A to the D. melanogaster genome, which causes recessive male sterility, was dissected by recombination, deficiency, and complementation mapping. The 450-kb region between two genes, Suppressor of Hairless and snail, exhibited a strong effect on the sterility. Males are (semi-)sterile if this region of the introgression is made homozygous or hemizygous. But no genes in the region singly cause the sterility; this region has at least two genes, which in combination result in male sterility. Further, the males are less fertile when heterozygous with a larger introgression, which suggests that dominant modifiers enhance the effects of recessive genes of male sterility. Such an epistatic view, even in the less-related species, suggests that the genetic complexity is special to hybrid male sterility.

The Breeding Evidence Indicating Two Genetic Types of Females of Ips tridens Mannerheim) (Coleoptera: Scolytidae)

1964 ◽  
Vol 96 (1-2) ◽  
pp. 117-118 ◽  
Author(s):  
G. R. Hopping
Keyword(s):  
Sex Ratio ◽  
Related Species ◽  
Mortality Factor ◽  
Unexpected Result ◽  
Closely Related Species ◽  
Inner Bark ◽  
Genetic Types ◽  
Stage Of Development ◽  
Gallery System ◽  
Entrance Hole

Members of the genus Ips are polygamous. The male excavates the entrance hole and a small nuptial chamber between the inner bark and sapwood. The females then enter and each excavates an egg gallery starting from the nuptial chamber. The number of females per gallery system ranges from 1 to 5 but the most common number is 3. This sex ratio of approximately 3 ♀ ♀: 1 ♂ has been attributed to some mortality factor more lethal to the males in some stage of development. Breeding of isolated pairs under laboratory conditions was carried out primarily to determine the variability between individuals from the same brood and between individuals from different broods. The objective was to resolve the complex of closely related species in the Ips tridens–I. engelmanni group. An unexpected result was a clarification of the sex ratio problem.

scholarly journals ON THE ORIGIN OF THE CULTIVATED CHENOPODS (CHENOPODIUM)

Genetics ◽  
1974 ◽  
Vol 78 (1) ◽  
pp. 503-505
Author(s):  
Charles B Heiser ◽  
David C Nelson
Keyword(s):  
South America ◽  
Related Species ◽  
Chenopodium Quinoa ◽  
Type A ◽  
Wild Type ◽  
Closely Related Species ◽  
The Andes

ABSTRACT On the basis of morphology Chenopodium quinoa of the Andes and C. nuttalliae of Mexico appear to be very closely related species. Artificial hybrids have been secured between the two. It is suggested that both species may have been derived from the same original wild type. A weedy quinoa, C. quinoa var. melanospermum, is known from South America, but as yet a weed race closely related to C. nutalliae has not been reported from Mexico.

scholarly journals Non-Mendelian Segregation of Sex Chromosomes in Heterospecific Drosophila Males

Genetics ◽  
2000 ◽  
Vol 154 (2) ◽  
pp. 687-694 ◽  
Author(s):  
Emmanouil T Dermitzakis ◽  
John P Masly ◽  
Heidi M Waldrip ◽  
Andrew G Clark
Keyword(s):  
Sex Ratio ◽  
Sex Chromosome ◽  
Recombinant Inbred Lines ◽  
Meiotic Drive ◽  
Drosophila Genome ◽  
Hybrid Male ◽  
Mendelian Segregation ◽  
Hybrid Male Sterility ◽  
Two Factors ◽  
Biased Sex Ratio

Abstract Interspecific hybrids and backcrossed organisms generally suffer from reduced viability and/or fertility. To identify and genetically map these defects, we introgressed regions of the Drosophila sechellia genome into the D. simulans genome. A female-biased sex ratio was observed in 24 of the 221 recombinant inbred lines, and subsequent tests attributed the skew to failure of Y-bearing sperm to fertilize the eggs. Apparently these introgressed lines fail to suppress a normally silent meiotic drive system. Using molecular markers we mapped two regions of the Drosophila genome that appear to exhibit differences between D. simulans and D. sechellia in their regulation of sex chromosome segregation distortion. The data indicate that the sex ratio phenotype results from an epistatic interaction between at least two factors. We discuss whether this observation is relevant to the meiotic drive theory of hybrid male sterility.

scholarly journals Further characterization of the Odysseus locus of hybrid sterility in Drosophila: one gene is not enough.

Genetics ◽  
1995 ◽  
Vol 140 (1) ◽  
pp. 201-206 ◽  
Author(s):  
D E Perez ◽  
C I Wu
Keyword(s):  
Related Species ◽  
Genetic Background ◽  
Hybrid Sterility ◽  
Weak Effect ◽  
Hybrid Male ◽  
Hybrid Male Sterility ◽  
Closely Related Species ◽  
Drosophila Mauritiana ◽  
Average Gene

Abstract Previously we mapped by genetical and molecular means a gene that contributes to hybrid-male sterility between Drosophila mauritiana and D. simulans to the cytological interval of 16D. In this report, we refine the mapping of this gene, Odysseus (Ods) and show that it can be delineated to a region the size of an average gene. We further demonstrate that, while Ods appears to be a discrete element, it requires other nearby gene(s) to be cointrogressed to confer full hybrid sterility effect. This observation is in agreement with the view that reproductive isolation between closely related species of Drosophila is usually caused by several genes of weak effect from the same species that interact strongly among themselves as well as with the foreign genetic background.

Modelling immunocontraception in disseminating systems

1997 ◽  
Vol 9 (1) ◽  
pp. 51 ◽  
Author(s):  
N. D. Barlow
Keyword(s):  
New Zealand ◽  
Population Density ◽  
Related Species ◽  
Breeding Population ◽  
Trichosurus Vulpecula ◽  
Wild Type ◽  
Target Species ◽  
Closely Related Species ◽  
Novel Technology ◽  
High Prevalence

Vectored immunocontraception is a novel technology and simple models are described to help predict whether, and how, it might work. That is, given that an effective immunocontraceptive agent can be produced, and given that it can be inserted into a microparasitic or macroparasitic infective vector, would the vector persist and reach a high prevalence in the host and, if so, would it sterilize a sufficient proportion of the host breeding population to significantly reduce its density? Both conditions are necessary for success. The first question is an epidemiological one, relating solely to disseminating systems and differing according to whether the vector itself is newly introduced or pre-existing. If it is newly introduced, the assumption is that it is present in some other geographical areas occupied by the same target species, or is found in closely-related species. If the vector already exists in the population, the issue is one of competition between the engineered and wild-type vectors. The second question is an ecological one, common to both non-disseminating and disseminating systems. Whatever level of sterilization the immunocontraception provides must translate into a significant reduction in population density, having regard to the nature and extent of compensatory, density-dependence mechanisms in the population. These two questions, together with other more minor issues, are addressed in turn with particular reference to models for immunocontraception of brushtail possums (Trichosurus vulpecula)in New Zealand.

Comparative AFLP reveals paternal sex ratio chromosome specific DNA sequences in the parasitoid wasp Trichogramma kaykai

Genome ◽  
2009 ◽  
Vol 52 (5) ◽  
pp. 447-455
Author(s):  
Joke J.F.A. van Vugt ◽  
Ron G.M. van der Hulst ◽  
Andrea J.P. Pruijssers ◽  
Patrick Verbaarschot ◽  
Richard Stouthamer ◽  
...  
Keyword(s):  
Sex Ratio ◽  
Dna Sequences ◽  
Related Species ◽  
Parasitoid Wasp ◽  
Specific Marker ◽  
Paternal Genome ◽  
Closely Related Species ◽  
Repetitive Nature ◽  
Aflp Fragment ◽  
Paternal Sex Ratio

The parasitoid wasp Trichogramma kaykai with a haplo-diploid sex determination has a B chromosome called the paternal sex ratio (PSR) chromosome that confers paternal genome loss during early embryogenesis, resulting in male offspring. So far, it is not well known whether the PSR chromosome has unique DNA sequence characteristics. By comparative AFLP fingerprinting of genomic DNA from wasps with and without the PSR chromosome, we isolated DNA from PSR-specific bands. Fourteen of such DNA fragments were analysed to confirm their PSR specificity. Seven were sequenced and two (PT-AFLP 1 and PT-AFLP1 3) were identified as parts of retrotransposon genes based on BLAST searches. Internal primers designed from a third AFLP fragment allowed PCR amplification of a PSR chromosome specific marker, which can be used to screen for the PSR trait in male wasps. Southern analysis revealed a dispersed repetitive nature of this third sequence in the T. kaykai genome, suggesting that it is part of a transposon. A fourth AFLP fragment (PT-AFLP 5) appears to be a large repetitive sequence on the PSR chromosome. This sequence is also found in the genome of both T. kaykai and the closely related species Trichogramma deion , but its distribution on the PSR chromosome strongly resembles that of T. deion rather than that of T. kaykai. Our results provide further insight into the repetitive nature of sequences comprising B chromosomes and their similarities with their host and closely related species.

scholarly journals The inherited bacterial symbiont Hamiltonella influences the sex ratio of an insect host

2019 ◽  
Vol 286 (1915) ◽  
pp. 20191677 ◽  
Author(s):  
Hong-Wei Shan ◽  
Jun-Bo Luan ◽  
Yin-Quan Liu ◽  
Angela E. Douglas ◽  
Shu-Sheng Liu
Keyword(s):  
Sex Ratio ◽  
Symbiotic Bacterium ◽  
Host Cells ◽  
Alternative Methods ◽  
Female Progeny ◽  
Compensatory Response ◽  
Reproductive Response ◽  
Biased Sex Ratio ◽  
Microbial Symbionts ◽  
Alternative Processes

In many intracellular symbioses, the microbial symbionts provide nutrients advantageous to the host. However, the function of Hamiltonella defensa , a symbiotic bacterium localized in specialized host cells (bacteriocytes) of a whitefly Bemisia tabaci , is uncertain. We eliminate this bacterium from its whitefly host by two alternative methods: heat treatment and antibiotics. The sex ratio of the host progeny and subsequent generations of Hamiltonella -free females was skewed from 1 : 1 (male : female) to an excess of males, often exceeding a ratio of 20 : 1. B. tabaci is haplodiploid, with diploid females derived from fertilized eggs and haploid males from unfertilized eggs. The Hamiltonella status of the insect did not affect copulation frequency or sperm reserve in the spermathecae, indicating that the male-biased sex ratio is unlikely due to the limitation of sperm but likely to be associated with events subsequent to sperm transfer to the female insects, such as failure in fertilization. The host reproductive response to Hamiltonella elimination is consistent with two alternative processes: adaptive shift in sex allocation by females and a constitutive compensatory response of the insect to Hamiltonella -mediated manipulation. Our findings suggest that a bacteriocyte symbiont influences the reproductive output of female progeny in a haplodiploid insect.

scholarly journals The Broom of the Sorcerer's Apprentice: The Fine Structure of a Chromosomal Region Causing Reproductive Isolation Between Two Sibling Species of Drosophila

Genetics ◽  
1996 ◽  
Vol 143 (3) ◽  
pp. 1287-1298 ◽  
Author(s):  
Andrew W Davis ◽  
Chug-I Wu
Keyword(s):  
Reproductive Isolation ◽  
Sibling Species ◽  
Related Species ◽  
Hybrid Sterility ◽  
Drosophila Genome ◽  
Hybrid Male ◽  
Hybrid Male Sterility ◽  
Closely Related Species ◽  
Drosophila Mauritiana ◽  
Two Factors

Abstract How many genes contribute to reproductive isolation between closely related species? We determined the number of genes located in the 9D-12B region of the Drosophila mauritiana X chromosome that cause hybrid male sterility in a D. simulans background. Previous low resolution studies suggested that a single hybrid sterility factor was associated with this region. In this study, by taking advantage of a cluster of visible and DNA markers, we identified three D. mauritiana factors in this region and then subjected one of them to detailed analysis. This factor again turned out to be comprised of three factors; one of which, mapped to within 200 kb, may in fact be two factors. The title refers to this exercise of splitting sterile introgressions into ever smaller ones, each of which retains partial or full sterility effects. In a region representing a mere 3% of the Drosophila genome, no fewer than six loci of hybrid sterility were identified between two sibling species that have not shown clear divergence at the molecular level. These results suggest that levels of genetic divergence between closely related species may be quite high for functionally important traits even when the opposite is true for randomly chosen loci.

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