A cytological study of Simulium ruficorne (Diptera: Simuliidae) and its relationship to the S. ornatipes species complex

Genome ◽  
1989 ◽  
Vol 32 (4) ◽  
pp. 570-579 ◽  
Author(s):  
D. G. Bedo
Keyword(s):  
Polytene Chromosome ◽  
Species Complex ◽  
Sex Chromosome ◽  
New Caledonia ◽  
Island Population ◽  
Chromosome Inversion ◽  
Banding Patterns ◽  
Close Relationship ◽  
Santiago Island

Polytene chromosome banding patterns in Simulium ruficorne populations from two island and a continental African locality were analyzed and a standard map was prepared. Distinct arrays of fixed and polymorphic rearrangements characterize unique cytotypes in Santiago Island, Tenerife, and Ivory Coast populations. Sex-chromosome differentiation where an inversion linked to the male determiner marks a Y chromosome also occurs in the Santiago Island population. No sibling species can be defined at present because of the absence of sympatric population samples. Comparison of banding patterns between S. ruficorne and the S. ornatipes–neornatipes species complex in Australia and New Caledonia shows striking similarities. Banding homology is readily established with about 90% of polytene banding recognizable between the two standards. Three inversions are shared between the lineages, further emphasizing their similarity. These results provide independent corroboration of the close relationship between S. ruficorne and S. ornatipes established from conventional taxonomy. The validity of using shared inversions and common breakpoints in phylogenetic comparisons is discussed in relation to the possibility of confusing similar but distinct rearrangements and the inversion-generating role of transposable elements. The possibility of transposable element mediated identical, independently derived, rearrangements seems unlikely, but in all studies the confusion of phylogenies by similar inversions must be carefully considered.Key words: Simulium ruficorne, polytene chromosome, inversion phylogeny.

Sibling species and sex chromosome differentiation in Simulium neornatipes (Diptera: Simuliidae)

1984 ◽  
Vol 26 (3) ◽  
pp. 318-325 ◽  
Author(s):  
D. G. Bedo
Keyword(s):  
Polytene Chromosome ◽  
Sibling Species ◽  
Sex Chromosomes ◽  
Sex Chromosome ◽  
Close Association ◽  
Chromosome Analysis ◽  
Sex Linkage ◽  
Direct Role ◽  
Chromosome Differentiation ◽  
Close Relationship

Polytene chromosome analysis of five Simulium neornatipes populations not only confirms the existence of the two sibling species, S. neornatipes 1 and 2, proposed earlier but reveals a third. S. neornatipes 3. These sibling species share a common standard polytene chromosome banding sequence which differs from the Australian S. ornatipes complex standard by five fixed inversions. The sharing of polymorphic inversions between the ornatipes and neornatipes complexes indicates their close relationship. The neornatipes species are distinguished from each other by additional fixed inversions and differentiated sex chromosomes. Extensive sex chromosome differentiation involving chromosome III has occurred in S. neornatipes 1 and 2. A period of incomplete sex-linkage allowing reassortment of inversions must have preceded the currently observed strong sex-linkage of differentiated sex chromosomes to account for the complex array of sex chromosomes found. The close association of sex chromosome differentiation with speciation in black flies is discussed in relation to appropriate speciation mechanisms. It is concluded that the rearrangements themselves have no direct role in the speciation process.Key words: sibling species, sex chromosomes, Simuliidae.

Polytene chromosome maps of the melon fly Bactrocera cucurbitae (Diptera: Tephritidae)

Genome ◽  
2002 ◽  
Vol 45 (6) ◽  
pp. 1167-1174 ◽  
Author(s):  
Reza M Shahjahan ◽  
Farzana Yesmin
Keyword(s):  
Salivary Gland ◽  
Polytene Chromosome ◽  
Sex Chromosome ◽  
Polytene Chromosomes ◽  
Chromosome Analysis ◽  
Bactrocera Cucurbitae ◽  
Mitotic Chromosomes ◽  
Larval Brain ◽  
Banding Patterns ◽  
Melon Fly

Standard photographic maps of the polytene chromosomes are presented for the melon fly Bactrocera cucurbitae, a serious pest of fleshy fruits and vegetables. Five larval salivary gland polytene chromosomes (10 polytene arms) were isolated, and their characteristic features and landmarks have been recognized. Banding patterns of each of the polytene arms are presented, where variation in band intensity and puffs appear to reflect fundamental differences in chromosomes. The whole polytene genome has been typically mapped by dividing it into 100 sections and the subsections were lettered. The mitotic chromosomes of larval brain ganglia are also examined, five pairs of autosomes and an XX/XY sex chromosome pair. In addition, a heterochromatic mass corresponding to the sex chromosomes are observed in the polytene nuclei of salivary gland tissue. This investigation showed that B. cucurbitae has excellent cytological material for polytene chromosome analysis and proved to be very useful for obtaining more detailed genetic information on the pest's natural populations.Key words: Bactrocera cucurbitae, salivary gland, banding patterns, polytene maps.

Lineages

2018 ◽  
Author(s):  
Ruth Gamble
Keyword(s):  
Thirteenth Century ◽  
Buddhist Tradition ◽  
Close Relationship

Chapter 2 examines lineages in Tibetan society and the Buddhist tradition and explains how they influenced the development of Tibet’s reincarnation lineages. It begins by explaining the role of family lineages in thirteenth-century Tibet, describing how lineages helped form identities, created links between people, and served as a mechanism for inheritance. It then examines the three main forms of Buddhist lineages—monastic, Mahāyāna, and Tantric—and shows how these lineages were often intermingled with Tibetan family lineages and inheritance practices. The chapter ends by outlining how lineages associated with manifestation, particularly lineages associated with Avalokiteśvara, underpinned claims by Tibetans to be the manifestation of this bodhisattva and other celestial beings. This chapter also explains how the Karmapas’ reincarnation lineage, traditions, and institutions were presented not as a break from other lineages but as an extension of them, and it highlights the close relationship between lineages and specific places.

Processing the Future

2018 ◽  
Author(s):  
Martin Giraudeau
Keyword(s):  
Venture Capital ◽  
Diagnostic Techniques ◽  
Business Administration ◽  
Knowledge Practices ◽  
Project Appraisal ◽  
Development Corporation ◽  
Close Relationship ◽  
Administrative Procedures ◽  
American Research

This chapter is an analysis of the project appraisal procedures in place at American Research and Development Corporation (ARD) between 1946 and 1973, under the management of Georges F. Doriot. It shows the importance of knowledge technologies and administrative procedures in the way the venture capital company dealt with uncertain futures. The origins of these knowledge practices are traced back to Georges F. Doriot’s own views on business and more generally to the pragmatist movement in business administration of which he was a member. The conduct of project appraisal at ARD is then observed directly, and this reveals its reliance on a rich set of knowledge and diagnostic techniques as well as administrative procedures. These observations allow for a specification of the nature and role of imagination in the entrepreneurship and venture capital practices examined here—in particular, its close relationship with organized knowledge.

scholarly journals Chromosomal Analysis in Crotophaga ani (Aves, Cuculiformes) Reveals Extensive Genomic Reorganization and an Unusual Z-Autosome Robertsonian Translocation

Cells ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 4
Author(s):  
Rafael Kretschmer ◽  
Ricardo José Gunski ◽  
Analía del Valle Garnero ◽  
Thales Renato Ochotorena de Freitas ◽  
Gustavo Akira Toma ◽  
...  
Keyword(s):  
Robertsonian Translocation ◽  
Chromosome Evolution ◽  
Sex Chromosome ◽  
Rare Event ◽  
Chromosome Morphology ◽  
Z Chromosome ◽  
Molecular Cytogenetic ◽  
Intrachromosomal Rearrangements ◽  
Genomic Reorganization

Although cytogenetics studies in cuckoos (Aves, Cuculiformes) have demonstrated an interesting karyotype variation, such as variations in the chromosome morphology and diploid number, their chromosome organization and evolution, and relation with other birds are poorly understood. Hence, we combined conventional and molecular cytogenetic approaches to investigate chromosome homologies between chicken and the smooth-billed ani (Crotophaga ani). Our results demonstrate extensive chromosome reorganization in C. ani, with interchromosomal rearrangements involving macro and microchromosomes. Intrachromosomal rearrangements were observed in some macrochromosomes, including the Z chromosome. The most evolutionary notable finding was a Robertsonian translocation between the microchromosome 17 and the Z chromosome, a rare event in birds. Additionally, the simple short repeats (SSRs) tested here were preferentially accumulated in the microchromosomes and in the Z and W chromosomes, showing no relationship with the constitutive heterochromatin regions, except in the W chromosome. Taken together, our results suggest that the avian sex chromosome is more complex than previously postulated and revealed the role of microchromosomes in the avian sex chromosome evolution, especially cuckoos.

Male Sterility and Meiotic Drive Associated With Sex Chromosome Rearrangements in Drosophila: Role of X-Y Pairing

Genetics ◽  
1998 ◽  
Vol 149 (1) ◽  
pp. 143-155 ◽  
Author(s):  
Bruce D McKee ◽  
Kathy Wilhelm ◽  
Cynthia Merrill ◽  
Xiao-jia Ren
Keyword(s):  
Male Sterility ◽  
Sex Chromosome ◽  
Meiotic Drive ◽  
Repeated Sequence ◽  
Meiotic Pairing ◽  
Intergenic Spacers ◽  
Male Specific ◽  
The Relationship ◽  
Novel Model

Abstract In Drosophila melanogaster, deletions of the pericentromeric X heterochromatin cause X-Y nondisjunction, reduced male fertility and distorted sperm recovery ratios (meiotic drive) in combination with a normal Y chromosome and interact with Y-autosome translocations (T(Y;A)) to cause complete male sterility. The pericentromeric heterochromatin has been shown to contain the male-specific X-Y meiotic pairing sites, which consist mostly of a 240-bp repeated sequence in the intergenic spacers (IGS) of the rDNA repeats. The experiments in this paper address the relationship between X-Y pairing failure and the meiotic drive and sterility effects of Xh deletions. X-linked insertions either of complete rDNA repeats or of rDNA fragments that contain the IGS were found to suppress X-Y nondisjunction and meiotic drive in Xh−/Y males, and to restore fertility to Xh−/T(Y;A) males for eight of nine tested Y-autosome translocations. rDNA fragments devoid of IGS repeats proved incapable of suppressing either meiotic drive or chromosomal sterility. These results indicate that the various spermatogenic disruptions associated with X heterochromatic deletions are all consequences of X-Y pairing failure. We interpret these findings in terms of a novel model in which misalignment of chromosomes triggers a checkpoint that acts by disabling the spermatids that derive from affected spermatocytes.

How Can Economic Interests Influence Support for Free Trade?

2012 ◽  
Vol 66 (2) ◽  
pp. 311-328 ◽  
Author(s):  
Benjamin O. Fordham ◽  
Katja B. Kleinberg
Keyword(s):  
Trade Policy ◽  
Free Trade ◽  
Well Being ◽  
Economic Interests ◽  
Policy Attitudes ◽  
Self Interest ◽  
Close Relationship ◽  
Direction Of Causation ◽  
Complete Account

AbstractRecent research on the sources of individual attitudes toward trade policy comes to very different conclusions about the role of economic self-interest. The skeptical view suggests that long-standing symbolic predispositions and sociotropic perceptions shape trade policy opinions more than one's own material well-being. We believe this conclusion is premature for two reasons. First, the practice of using one attitude to predict another raises questions about direction of causation that cannot be answered with the data at hand. This problem is most obvious when questions about the expected impact of trade are used to predict opinions about trade policy. Second, the understanding of self-interest employed in most studies of trade policy attitudes is unrealistically narrow. In reality, the close relationship between individual economic interests and the interests of the groups in which individuals are embedded creates indirect pathways through which one's position in the economy can shape individual trade policy preferences. We use the data employed by Mansfield and Mutz to support our argument that a more complete account of trade attitude formation is needed and that in such an account economic interests may yet play an important role.1

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