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PubMed2006

Global genetic change tracks global climate warming in Drosophila subobscura.

Comparisons of recent with historical samples of chromosome inversion frequencies provide opportunities to determine whether genetic change is tracking climate change in natural populations. We determined the magnitude and direction of shifts over time (24 years between samples on average) in chromosome inversion frequencies and in ambient temperature for populations of the fly Drosophila subobscura on three continents. In 22 of 26 populations, climates warmed over the intervals, and genotypes characteristic of low latitudes (warm climates) increased in frequency in 21 of those 22 populations. Thus, genetic change in this fly is tracking climate warming and is doing so globally.

Animals↗
PubMed1990

Genetic and molecular analysis of vgU and vgW: two dominant vg alleles associated with gene fusions in Drosophila.

In the absence of a vg+ gene, extensive cell death occurs in third instar imaginal discs, which results in a complete loss of adult wing margin structures. Essentially all molecularly characterized vg alleles are associated with deletions or insertions of DNA into the vg locus. These alterations reduce or eliminate a 3.8-kb vg-specific transcript, resulting in recessive loss of function alleles. We report here the analysis of two dominant vg alleles which have been identified (vgU and vgW). The vgU allele is associated with a chromosomal inversion which splits the vg locus, resulting in a gene fusion between vg and the mastermind (mam) neurogenic locus. Reversion analysis of vgU indicates that sequences from the mam locus are required for vgU dominance. The vgW allele is also the result of a chromosomal inversion, in this case resulting in a gene fusion between vg and the homeobox-containing invected (inv) gene. It is also associated with novel dominant homeotic transformations. Revertant analysis indicates that sequences from inv are required for the dominant wing and dominant homeotic effects of vgW. The vg dominance does not appear to be mediated through a reduction of vg expression or a novel fusion transcript in either vgU or vgW. The results are consistent with a model in which inappropriate expression of inv causes the dominant homeotic effects seen in vgW.

Alleles↗
PubMed1981

Normal psychomotor development in a child with mosaic trisomy and pericentric inversion of chromosome 9.

A female infant with trisomy 9 in 58% of her cells is reported. Multiple congenital malformations were present, but she had normal psychomotor development. A pericentric inversion involving a portion of the centromeric heterochromatin of chromosome 9 was identified in the patient and her mother. This variant chromosome 9 was present in duplicate in the trisomic line. Since similar variants of 9qh have been found repeatedly in this syndrome, we feel that this association may be a non-random one.

Chromosome Banding↗
PubMed1995

Comparison of gamma-ray-induced chromosome ring and inversion frequencies.

A method was used to detect chromosome inversions as apparent or false sister chromatid exchanges (SCEs) in the first mitosis after gamma irradiation of human G0 cells. Dose-response relationships for small inversions have not been measured and reported previously, but it has been assumed that these are induced with a frequency equal to that of their easily measured asymmetrical counterpart, the interstitial deletion. Our experiments confirm this expectation. The results also demonstrate, as others have suggested, that in protocols where SCEs have been reported in the first postirradiation mitosis after incorporation of BrdU in the previous cell cycle, the X- or gamma-ray treatment of G0- or G1-phase cells produces virtually no true SCEs.

Cell Line↗
PubMed1994

Chromosomal pericentric inversion detected in a sow and her piglets.

Forty-four pigs with the suspicious symptoms of porcine stress syndrome (PSS) were selected for chromosome analysis. Cytogenetic evaluation by means of the G-banding technique revealed that one sow had an abnormal (38,XX, inv (1p+q-) (2.1;1.1) karyotype. The same abnormality was also detected in 8 of 13 offspring of this sow. However, there was no correlation between the chromosome abnormality and PSS. The chromosome abnormality did not give rise to a reduction in the fertility of this sow or in the viability of her offspring. This case represents the first reported instance of pericentric inversion in swine.

Journal Article↗
PubMed2001

Physical localization and order of genes in the class I region of the bovine MHC.

Fluorescence in situ hybridization (FISH) analyses were used to order 16 bacterial artificial chromosomes (BAC) clones containing loci from the bovine lymphocyte antigen (BoLA) class I and III regions of bovine chromosome 23 (BTA23). Fourteen of these BACs were assigned to chromosomal band locations of mitotic and pachytene chromosomes by single- and dual-colour FISH. Dual-colour FISH confirmed that class II DYA is proximal to and separated from BoLA class I genes by approximately three chromosome bands. The FISH results showed that tumour necrosis factor alpha (TNFA), heat shock protein 70 (HSP70.1) and 21 steroid dehydrogenase (CYP21) are closely linked in the region of BTA23 band 22 along with BoLA class I genes, and that male enhanced antigen (MEA) mapped between DYA and the CYP21/TNFA/HSP70.1 gene region. All BAC clones containing BoLA class I genes mapped distal to CYP21/TNFA/HSP70.1 and centromeric to prolactin (PRL). Myelin oligodendrocyte glycoprotein (MOG) was shown to be imbedded within the BoLA class I gene cluster. The cytogenetic data confirmed that the disrupted distribution of BoLA genes is most likely the result of a single large chromosomal inversion. Similar FISH results were obtained when BoLA DYA and class I BAC clones were mapped to discrete chromosomal locations on the BTA homologue in white-tailed deer, suggesting that this chromosomal inversion predates divergence of the advanced ruminant families from a common ancestor.

Animals↗
PubMed1992

High density molecular linkage maps of the tomato and potato genomes.

High density molecular linkage maps, comprised of more than 1000 markers with an average spacing between markers of approximately 1.2 cM (ca. 900 kb), have been constructed for the tomato and potato genomes. As the two maps are based on a common set of probes, it was possible to determine, with a high degree of precision, the breakpoints corresponding to 5 chromosomal inversions that differentiate the tomato and potato genomes. All of the inversions appear to have resulted from single breakpoints at or near the centromeres of the affected chromosomes, the result being the inversion of entire chromosome arms. While the crossing over rate among chromosomes appears to be uniformly distributed with respect to chromosome size, there is tremendous heterogeneity of crossing over within chromosomes. Regions of the map corresponding to centromeres and centromeric heterochromatin, and in some instances telomeres, experience up to 10-fold less recombination than other areas of the genome. Overall, 28% of the mapped loci reside in areas of putatively suppressed recombination. This includes loci corresponding to both random, single copy genomic clones and transcribed genes (detected with cDNA probes). The extreme heterogeneity of crossing over within chromosomes has both practical and evolutionary implications. Currently tomato and potato are among the most thoroughly mapped eukaryotic species and the availability of high density molecular linkage maps should facilitate chromosome walking, quantitative trait mapping, marker-assisted breeding and evolutionary studies in these two important and well studied crop species.

Centromere↗
PubMedDate not supplied

Analysis of inbreeding in a colonizing population of Drosophila subobscura.

An analysis of the effects of inbreeding on the genetic structure of a colonizing population of Drosophila subobscura has been carried out. Species of Drosophila, particularly D. subobscura, may have lethal alleles associated with chromosomal inversions and our aim was to assess the extent to which the genome is balanced in this way. The frequencies of chromosomal inversions were compared between a large population and a set of 72 lines that were maintained by brother-sister mating for 10 generations. Fisher's matrix method was used to calculate the expected homozygosity in these inbred lines for 5 allozyme loci (Aph, Hk-1, Lap, Odh, and Pept-1) used as markers of large chromosomal segments. Furthermore, the expected rates of fixation corresponding to these allozyme loci were also calculated. The results show that the amount of homozygosis observed did not differ significantly from expectations (with the corresponding loss of lines as a consequence of the reduction in viability). However, two deviations from strict neutrality were observed: there was a heterozygote excess at the Lap locus, and the frequency of the O5 inversion (always associated with a lethal gene in colonizing populations) was higher than expected.

Animals↗
PubMed1986

Theoretical study of inversions affecting human chromosomes.

A theoretical study of inversions affecting human chromosomes is proposed. Taking into consideration the number of bands and the fact that breaks occur at interfaces between bands, it is concluded that: 7.659 different pericentric inversions might be detected in a prometaphasic 802-band karyotype; this number decreases to 917 in a metaphasic 273-band karyotype; 8.607 and 862 different paracentric inversions might be detected in the same karyotypes respectively, but these results are likely to be overestimated. These theoretical data are used for showing that the pericentric inversions detected in human cytogenetic laboratories, are too frequently recurrent and are not distributed at random.

Chromosome Inversion↗
PubMed2002

A polytene chromosome analysis of the Anopheles gambiae species complex.

Field-collected specimens of all known taxa in the Anopheles gambiae complex were analyzed on the basis of chromosome inversions with reference to a standard polytene chromosome map. The phylogenetic relationships among the seven described species in the complex could be inferred from the distribution of fixed inversions. Nonrandom patterns of inversion distribution were observed and, particularly on chromosome arm 2R, provided evidence for genetically distinct populations in A. gambiae, A. arabiensis, and A. melas. In A. gambiae from Mali, stable genetic differentiation was observed even in populations living in the same region, suggesting a process of incipient speciation which is being confirmed by studies with molecular markers. The possible role of chromosome differentiation in speciation of the A. gambiae complex and in the emergence of distinct chromosomal forms within the nominal species is discussed in relation to human malaria.

Africa↗
PubMed1982

X-linked mental retardation with a fragile site in Xq and an inversion of chromosome no. 9.

The second black male with X-linked mental retardation and a fragile site at Xq27 was ascertained by screening for macroorchidism. GTG banding revealed the presence of an inv(9)(p13q21). This inversion is thought to be a chance occurrence and is probably of no clinical significance. More cases having a marker Xq and a chromosome abnormality are expected; some of these abnormalities will be clinically significant.

Chromosome Aberrations↗
PubMed1989

Acute nonlymphocytic leukemia in a patient with a constitutional inv(4).

We describe a case of acute nonlymphocytic leukemia (ANLL) in a patient with a constitutional chromosome anomaly, inv(4)(p16q26). The patient had extensive occupational exposure to toxic chemicals. Reports of constitutional or acquired chromosome inversions in human malignancies are quite uncommon. The constitutional changes associated with hematologic malignancies include trisomy 21, balanced translocations, deletions, and sex chromosome anomalies. The breakpoints on chromosome 4 in our case are 4p16, to which the murine leukemia viral (v-raf) oncogene, pseudogene 1, has been mapped, and 4q26, which is the locus of the IL-2 gene. Activation of these genes could have played a role in the pathogenesis of the patient's leukemia.

Aged↗
PubMed1996

Evolution of the mitochondrial DNA control region in the Anopheles gambiae complex.

We have sequenced the AT-rich control region of the mitochondrial DNA (mtDNA) of six species in the Afrotropical Anopheles gambiae complex and the closely related A. christyi. Contrary to expectations, the AT-rich region in this group is evolving rather slowly, more slowly than the third position of mtDNA protein-coding genes. Despite being relatively conserved between species, we detected intraspecific and intra-individual (heteroplasmy) variation in this region. Phylogenetically, we found we could place the rare endemic A. bwambae as a sister taxon to A. melas, the same evolutionary position as indicated by chromosomal inversions. The outgroup, A. christyi, gave evidence of the root of the tree. In comparing the molecular trees with that deduced by chromosomal inversions, they are completely congruent with the exception of the placement of A. arabiensis. The anomalous position of this species can be explained by introgression with A. gambiae. From the phylogenetic position, we could infer mtDNA gene flow from A. gambiae to A. arabiensis.

Animals↗
PubMed2006

Guide to blackflies of the Simulium damnosum complex in eastern and southern Africa.

At least 26 members of the Simulium damnosum Theobald complex (Diptera: Simuliidae) are known from eastern Africa, most of which are assumed to be non-anthropophilic and some are restricted to small areas of endemicity. Their discovery was based on polytene chromosome inversion polymorphisms and since then they have been cited as cytological entities, but, in many cases, with inadequate descriptions (e.g. without illustrations of the chromosomes). The present distribution, taxonomy and vector identity have been re-evaluated during the last decade in conjunction with ongoing onchocerciasis control programmes. Here, a summary of the relevant data is presented, integrating results of cytotaxonomic, morphotaxonomic and molecular investigations into a guide that provides a comprehensive system of identification for the cytoforms 'Kagera', 'Kasyabone', 'Kibwezi', 'Kisiwani', 'Kisiwani E', 'Kulfo', 'Linthipe', 'Mombo', 'Mutonga', 'Njombe', 'Nkusi', 'Nkusi SA', 'Nkusi SW', 'Nyika', 'Pienaars', 'Sanje', 'Sebwe', 'Turiani', Simulium damnosum sensu stricto, Simulium kaffaense Hadis et al., Simulium kilibanum Gouteux, Simulium kipengere Krueger, Simulium latipollex (Enderlein), Simulium pandanophilum Krüger, Nurmi & Garms, Simulium plumbeum Krueger, Simulium thyolense Vajime et al. and for five newly recognized molecular forms of 'Nkusi' and S. kilibanum. All taxa except S. pandanophilum are assigned to one of five subcomplexes (damnosum, Ketaketa, Kibwezi, Sanje, squamosum) within the S. damnosum complex. The guide encompasses anthropophilic and non-anthropophilic segregates for the whole of eastern and southern Africa, and is not restricted to larval chromosome criteria; in many cases it also allows the typing of adult flies.

Africa, Eastern↗