Inversion polymorphism in malaria mosquito Anopheles messeae. Part X. Resistance of larvae with different genotypes to toxins of crystal-forming bacteria Bacillus thuringiensis subsp. israelensis (serovar H14)

Insensibility of larvae with different chromosomal inversions to the toxins of Bacillus thuringiensis subsp. israelensis (Bti) was examined. It has been shown that larvae with inversion combinations XL0(XL1)2R0-3R0-3L0 had greater variability after treatment with Bti than larvae with inversions XL1(XL2)2R1-3R1-3L1(3L0). The former inversion combinations were previously shown to dominate in the south of the species area and to be supported by K-selection. The latter inversion combinations form "northest" karyotypes and are supported by r-selection. It is obvious that genetic effects of treatments with Bti depend on the population's structure and the directions of natural selection. The decrease in the level of heterozygotes after treatment of larvae with Bti reflects destruction of the system of genetic homeostasis in the natural populations of A. messeae.     

Changes in chromosomal polymorphism and global warming: The case of Drosophila subobscura from Apatin (Serbia)

In this study, chromosomal inversion polymorphism data for a natural population of Drosophila subobscura from a swampy region near the town of Apatin (Serbia) were compared with data for the same population collected approximately 15 years earlier. The pattern of chromosomal inversion polymorphism changed over time. There were significant increases in the frequency of characteristic southern latitude ("warm" adapted) chromosomal arrangements and significant decreases in the frequency of characteristic northern latitude ("cold" adapted) chromosomal arrangements in the O and U chromosomes. The chromosomal arrangements O(3+4) and O(3+4) (+) (22) (derived from the O(3+4) arrangement) showed significant increases in 2008 and 2009 with regard to the 1994 sample. There was also a significant increase (～50%) in the U(1) (+) (2) arrangement, while U(1+8) (+) (2) (a typical southern arrangement) was detected for the first time. Since the Apatin swampy population of D. subobscura has existed for a long time in a stable habitat with high humidity that has not been changed by man our results indicate that natural selection has produced chromosomal changes in response to the increase in temperature that has occurred in the Balkan Peninsula of central southeastern European.     

Seasonal changes of chromosomal inversion polymorphism in a Drosophila subobscura natural population from southeastern European continental refugium of the last glaciation period

Chromosomal inversion polymorphism was studied in a natural population of Drosophila subobscura from Djerdap gorge of Danube river, that represents one of southeastern European continental refugiums during last glaciation period. The existence for changes of chromosomal inversion polymorphism during different periods of time was tested. Observed very high abundance of chromosomal arrangements and lower IFR value grouped this population to central European populations. It was characterized with O7 and O(3+4+5) arrangements, not found in other populations from the region analyzed. Except in this population from warmer habitat, observed E(1+2+9+12) chromosomal arrangement was found, in the region analyzed, only in one population from Mediterranean refugial area. Many similarities have been observed between population from Djerdap gorge and other populations from the region analyzed, indicating that process of post-glacial migration may have started from this southeastern European refugium area. Seasonal changes in the frequencies for Est and O(3+4+7) chromosomal arrangements where Est was more frequent during the spring period and O(3+4+7) during the summer period were found. The changes for J-chromosome (Jst/Jst), E-chromosome (Est/E(1+2+9); E(8)/E(1+2+9) and O-chromosome (Ost/O(3+4+22); O(3+4)/O(3+4); O(3+4+1)/O(3+4+7) whose karyotypic combination frequencies were associated with seasonal changes were also found. These changes most probably represent associations with seasonal climatic changes in the population analyzed, supporting adaptivity of chromosomal inversions in D. subobscura.     

The Anopheles gambiae complex in Guinea Bissau

Three species of the Anopheles gambiae complex were identified in Guinea Bissau (West Africa) by chromosomal analysis. They were An. melas, An. arabiensis and An. gambiae s.s. An melas was observed in coastal and insular zones of the study area as well as in areas where the rivers are tidal and brackish and bordered by mangroves. For this reason, the species occurs also in inland riverine localities such as Farim and Bissorà. An. arabiensis apparently occurs only in low numbers in a very limited inland area during the dry season. An gambiae s.s. was observed nearly everywhere in the study area. In the samples of An. melas three inversion polymorphisms occurred: one on the chromosomal arm 2R (2Rn) and two on the arm 3R (3Rc and 3Re). It was observed that the frequencies of the inverted arrangements 2Rn and 3Re were significantly higher in the islands as compared to the continental sampling localities. The An. arabiensis sample was characterized by the presence of three inversion polymorphisms: 2Ra, 2Rb and 3Ra. A very high degree of polymorphism was shown by the An. gambiae s.s. samples. Four inversion polymorphisms were observed (three on chromosomal arm 2R and one on arm 2L) with very different frequencies of the alternative arrangements in different zones of the study area. From these data it seemed possible to split the species into three populations, each of them apparently linked with a peculiar ecological situation. The first population, characterized by high frequencies of 2Rd arrangement, is present on the coastal zones and in the islands; the second one is present in the northern inland areas particularly during the dry season and it is characterized by high frequencies of 2Rb and 2La arrangements. The third population is present only in the inland zones and it is characterized by high frequencies of 2Rjb, 2Rjd and 2Rjbd arrangements.     

Chromosomal inversion polymorphism of Anopheles funestus from forest villages of South Cameroon.

The polymorphism of paracentric inversions of Anopheles funestus polytene chromosomes was studied in three villages (Nkoteng, Obala, and Simbock) located in a forest area of South Cameroon in order to analyse the genetic structure of these populations. A total of 146-210 chromatids could be scored from specimens collected over about two years. A low degree of chromosomal polymorphism was observed with two floating inversions on chromosomal arm 2 (2h and 2d), and three fixed arrangements on arms 3 (3a and 3b), and 5 (5a). Such arrangement of inversions has never been recorded elsewhere so far. The chromosome analysis indicated that the population from Obala was in Hardy-Weinberg equilibrium, whereas the samples from Nkoteng and Simbock showed a significant excess and deficit of heterokaryotypes, respectively. Significant differences in inversion frequencies on chromosomal arm 2 among villages lying in contrasting eco-climatic settings suggested an adaptive role of these inversions.     

Inversion polymorphism in the malaria mosquito Anopheles messeae. VII. Fertility and the population genetics structure of the species

The role of chromosomal inversional complexes of different fecundity has been studied in the process of formation of karyotypic populational structure. Females with homozygotes 2R11 and "north-est" inversional combinations are shown to have maximal total egg production, while females with three or four inversional heterozygotes from XL01, XL12, 2R01, 3R01 and 3L01 demonstrated lower level of fecundity. It is found that the seasonal conversion from r-selection to K-selection occurs in the period of population "prosperity" (July). The results of such conversion are destruction of "northest" genocomplexes and reduction of relative fecundity of inversional homozygotes 2R11-Alternative tendencies take place at the beginning of the reproductive period.     

Familial pericentric inversion (3)(p12q24)

Summary A large kindred with a familial pericentric inversion of chromosome 3, (p12q24), was found after an investigation initiated by a young female with three spontaneous first-trimester abortions. Altogether 22 (33%) inversion carriers were discovered, 9 females and 13 males. 6 women and 9 men were included in the fertility and segregation analyses because they were all either sexually mature or past maturity. The abortion frequency was below the average European rate in both the inversion carrier group and the cytogenetically normal relative group; 6%: 3%, respectively. The mean numbers of pregnancies and live births (1.8–3.1) did not vary significantly in the two comparison groups. The segregation analysis among the inversion carriers showed a good correspondence to the theoretical 11 ratio (1613). Males and females contributed equally. No duplication/deletion syndromes have been found in the kindred; all family members are phenotypically normal. We report a balanced familial pericentric inversion with no adverse effects. This chromosome aberration could be an example of a harmless chromosome polymorphism.     

Chromosomal evidence of incipient speciation in the Afrotropical malaria mosquito Anopheles funestus

The analysis of chromosomal polymorphism of paracentric inversions in anopheline mosquitoes has often been instrumental to the discovery of sibling species complexes and intraspecific genetic heterogeneities associated with incipient speciation processes. To investigate the population structure of Anopheles funestus Giles (Diptera: Culicidae), one of the three most important vectors of human malaria in sub-Saharan Africa, a three-year survey of chromosomal polymorphism was carried out on 4,638 karyotyped females collected indoors and outdoors from two villages of central Burkina Faso. Large and temporally stable departures from Hardy-Weinberg equilibrium due to significant deficits of heterokaryotypes were found irrespective of the place of capture, and of the spatial and temporal units chosen for the analysis. Significant linkage disequilibrium was observed among inversion systems on independently assorting chromosomal arms, indicating the existence of assortative mating phenomena. Results were consistent with the existence of two chromosomal forms characterized by contrasting degrees of inversion polymorphism maintained by limitations to gene flow. This hypothesis was supported by the reestablishment of Hardy-Weinberg and linkage equilibria when individual specimens were assigned to each chromosomal form according to two different algorithms. This pattern of chromosomal variability is suggestive of an incipient speciation process in An. funestus populations from Burkina Faso.     

Cytogenetics of the Anopheles gambiae complex in Sudan, with special reference to An. arabiensis: relationships with East and West African populations

The species composition of malaria vector mosquitoes belonging to the Anopheles gambiae complex (Diptera: Culicidae) from >40 localities in Sudan, representing most ecological situations, was determined by analysis of ovarian polytene chromosomes. Of 2162 females, 93% were identified as An. arabiensis Patton and 7% were An. gambiae Giles sensu stricto. No hybrids were found between the two species. Anopheles arabiensis occurred in all but two sites, whereas An. gambiae s.s. was effectively limited to the southernmost, more humid localities. For chromosomal paracentric inversions, the degree of polymorphism was low in An. gambiae s.s. (inversions 2La, 2Rb and 2Rd), higher in An. arabiensis (inversions Xe, 2Ra, b, bc, d1, s; 3Ra, d). Anopheles gambiae samples from Sudan were all apparently panmictic, i.e. they did not show restricted gene flow such as observed among West African populations (interpreted as incipient speciation). Chromosomal inversion patterns of An. gambiae in southern Sudan showed characteristics of intergrading Savanna/Forest populations similar to those observed in comparable eco-climatic situations of West Africa. Anopheles arabiensis was polymorphic for inversion systems recorded in West Africa (2Ra, 2Rb, 2Rdl, 3Ra) and for a novel 2Rs polymorphism, overlapping with inversion systems 2Rb and 2Rd1. Samples carrying the 2Rs inversion were mostly from Khashm-el-Girba area in central-eastern Sudan. In the great majority of the samples all polymorphic inversions were found to be in Hardy-Weinberg equilibrium. Sudan populations of An. arabiensis should therefore be considered as generally panmictic. Anopheles arabiensis shows more inversion polymorphism in west than in east African populations. Sudan populations have more evident similarities with those from westwards than those from eastwards of the Great Rift Valley. The possible influence of the Rift on evolution of An. arabiensis is discussed.     

Adaptive association of inversions in a natural population of the malaria mosquito Anopheles messeae Fall.]

The dependent combination of chromosomal variants by five paracentric inversions (IL1, IL2, IIR1, IIIR1, IIIL1) in Anopheles messeae population from the West Siberia was discovered. It is found that the inversion interactions interactions are the same at both larval and imaginal parts of the population, and they are stable during four years of studying. The inversion of hetero- and homozygotes demonstrates identical properties, that is, phylogenetic secondary sequencies dominate in heterozygotes. Two associative groups of chromosome variants were revealed. The association correlates with geographic distribution and temporal dynamics of inversions and on the whole, it reflects the evolutionary history of inversion polymorphism in A. messeae. It is supposed that the adaptive association of inversions found is the high degree polymorphism formed and functioned on the basis of the groups of inversion chromosome blocks.     

Speciation and chromosomal evolution of the Baikalian endemic chironomids of the genus Sergentia Kief. (Diptera, Chironomidae): karyotype divergence and chromosomal polymorphism in the populations of eurybathic species Sergentia flavodentata Tshern. and littoral species Sergentia baicalensis Tshern

Specific karyotype structure and chromosomal polymorphism was investigated in the populations of the Baikalian endemic chironomid species, eurybathic Sergentia flavodentata Tshernovskij, 1949 and littoral Sergentia baicalensis Tshernovskij, 1949. In addition to two fluctuating homozygous inversions in arms A and E, both species were characterized by species-specific karyotype features, namely, nucleolar organizer in the region 1 of chromosome IV in S. flavodentata, and inversion in arm F in S. baicalensis. Moreover, S. baicalensis demonstrated the presence of intraspecific population polymorphism. The populations differing in the presence of secondary overlapping inversion in arm A were found. The highest number of chromosomal rearrangements (7) was detected in S. flavodentata. Most of these rearrangements (six) were found in the population from the underwater thermal spring at a depth of 420 to 430 m (Northern Baikal, Frolikha Bay). In the populations from Middle and Southern Baikal, a rare pericentric inversion in chromosome I was described. In S. baicalensis, in addition to two common heterozygous inversions in arms C and F, disturbance of homologous pairing in different regions of the remaining arms were often detected. Stable chromosomal polymorphism preserved during 13 years in the population of S. flavodentata from the region of hydrothermal venting, serves as an evidence of high genetic plasticity of the species, which favors successful colonization of different Baikal depths and biotopes.     

Chromosomal polymorphism in the populations of malaria vector mosquito Anopheles messeae at the south of Russian Plain

Zonal features of the geographic distribution of chromosomal inversions in the populations of An. messae at the south of the Russian Plain were examined. The An. messae was identified based on morphological characters and cytogenetically. The chromosomal inversions identified in populations of An. messae comprised XL₁, XL₄, 2R₁, 3R₁, and 3L₁. Inversion XL₄ was endemic and found with low frequency (2%) in Penza oblast and Moscow oblast. Based on the population karyotype structure similarity, on the territory of Russian Plain, three zones (southwestern, southeastern, and central) were identified. Central zone was characterized by higher levels of inversion polymorphism in all chromosomes, except arm 3L. In the two southern zones, high frequency of the XL₀ inversion, along with complete absence of homo- and heterozygotes for the 2R₁ inversion, and high proportion of the individuals with inversion 3L₁ was observed. Specific feature of southeastern zone was the increased frequency of hetero- and homozygotes for the 3R₁ and 3L₁ inversions. Zonal differences reflected adaptive character of chromosomal polymorphism and pointed to hierarchic organization of the species population structure.     

Geographic variability of the polytene chromosome banding sequence of non-biting midge <Emphasis Type="Italic">Chironomus pseudothummi</Emphasis> Str. (Diptera,Chironomidae)

The karyotypes and chromosomal polymorphism of Chironomus pseudothummi were investigated in different parts of its areal. It was established that chromosomal variability in the natural populations of this species was represented mainly by the inversion polymorphism of arm G. Only rare and unique inversions were found to be heterozygous in arms C, D, and E. In total, 14 banding sequences of polytene chromosomes form the banding sequence pool of C. pseudothummi. Geographic differences in the distribution of chromosomal banding sequences throughout the areal were established. The presence of banding sequences pstG1 and pstG2 is characteristic of European populations. The banding sequence pstG1 disappeared completely with a simultaneous increase in the frequency of pstG2 and with the appearance of a new inversion banding sequence pstG3 in Siberian populations. Differences in the set of rare and unique inversions in arms C, D, and E between the West-European and West-Siberian populations have been revealed.     

The evolutionary history of Drosophila buzzatii. XVI. Fitness component analysis in an original natural population from Argentina

The adaptive significance of the chromosomal polymorphism of Drosophila buzzati has been studied by means of fitness component analysis in an original population from Argentina. The results show evidence of selection acting through pupal viability, longevity (adult viability) and fecundity on the second chromosome polymorphism, and through pupal viability and virility on the fourth chromosome polymorphism. Changes in chromosomal inversion frequencies throughout the life-cycle suggested an endocyclic pattern of directional selection, which at first seems to be the only detectable mechanism responsible for the maintenance of the polymorphism. However, slow, long-term frequency changes cannot be ruled out. The way in which endocyclic selection acts on this population is different from that in a colonized population previously studied; that is, different fitness components are involved in the maintenance of chromosomal polymorphism. The possible factors that may explain these differences are discussed.     

Pollen viability restoration in a <Emphasis Type="Italic">Coffea canephora</Emphasis> P. and <Emphasis Type="Italic">C. heterocalyx</Emphasis> Stoffelen backcross. QTL identification for marker-assisted selection

Male fertility of interspecific hybrids was analysed in one F1 and two backcrossed progenies originating from a cross between Coffea canephora and Coffea heterocalyx. Male fertility was tested using pollen stainability with acetic carmine. The results showed a marked decline in fertility at the F1 level, and fertility was almost fully restored after two backcrosses. The computed broad-sense heritability represented 47% of the variance. Quantitative trait loci (QTLs) locations and effects on pollen viability were estimated using an amplified fragment length polymorphism (AFLP) genetic linkage map constructed in the segregating BC1 population. Three significant QTLs (LOD>3 and p < 0.001 by ANOVA) were detected for pollen viability, two of which were responsible for the bimodal distribution of pollen viability in the segregating population. One QTL was involved in fertility variations among fertile BC1 plants. Fertility inheritance is discussed in relation with previously demonstrated chromosomal sterility in Coffea hybrids and the effect of detected QTLs. The potential use of genetic markers to overcome sterility in interspecific hybrids is also discussed.     

Genetic loads and coadaptivity of chromosomal inversions I. Inversion polymorphism and genetic load on chromosome O in a Drosophila subobscura population from Petnica

Inversion polymorphism on chromosome O and polymorphism for the viability of determining genes have been studied in a natural population of Drosophila subobscura from Petnica (Serbia). The range of inversion polymorphism and the abundance of particular gene arrangements in the study population agree with a general pattern of inversion polymorphism of D. subobscura in Europe. The data obtained on the amount of genetic loads show that the D. subobscura population from Petnica displays a moderate degree of that polymorphism, compared to the other studied populations of these species. Therefore, the D. subobscura population from Petnica could be tentatively classified as an ecologically central population. Examination association of chromosomal, thus, inversion polymorphism with gene polymorphism, in the form of genetic loads show that differences exist in the mean viability among certain gene arrangements. The distribution of deleterious genes among chromosome O gene arrangements were non-random.     

Speciation and chromosomal evolution of the Baikalian endemic chironomids of the genus Sergentia Kief. (Diptera, Chironomidae): Karyotype divergence and chromosomal polymorphism in the populations of eurybathic species Sergentia flavodentata Tshern. and littoral species Sergentia baicalensis Tshern

Specific karyotype structure and chromosomal polymorphism was investigated in the populations of the Baikalian endemic chironomid species, eurybathic Sergentia flavodentata Tshernovskij, 1949 and littoral Sergentia baicalensis Tshernovskij, 1949. In addition to two fluctuating homozygous inversions in arms A and E, both species were characterized by species-specific karyotype features, namely, nucleolar organizer in the region 1 of chromosome IV in S. flavodentata, and inversion in arm F in S. baicalensis. Moreover, S. baicalensis demonstrated the presence of intraspecific population polymorphism. The populations differing in the presence of secondary overlapping inversion in arm A were found. The highest number of chromosomal rearrangements (7) was detected in S. flavodentata. Most of these rearrangements (six) were found in the population from the underwater thermal spring at a depth of 420 to 430 m (Northern Baikal, Frolikha Bay). In the populations from Middle and Southern Baikal, a rare pericentric inversion in chromosome I was described. In S. baicalensis, in addition to two common heterozygous inversions in arms C and F, disturbance of homologous pairing in different regions of the remaining arms were often detected. Stable chromosomal polymorphism preserved during 13 years in the population of S. flavodentata from the region of hydrothermal venting, serves as an evidence of high genetic plasticity of the species, which favors successful colonization of different Baikal depths and biotopes. Original Russian Text ? V.I. Proviz, 2008, published in Genetika, 2008, Vol. 44, No. 9, pp. 1191–1202.     

Human chromosomal polymorphism

Summary Chromosomal Q polymorphism was studied in 157 adolescents of Yakut nationality (67 males and 90 females) living in Eastern Siberia, on the territory of the Yakut ASSR. Of the 157 subjects, 123 had chromosomal Q variants while 34 (21.7%) had no Q-heterochromatin bands with fluorescence levels 4 and 5. The mean number of Q variants per individual ranged from 0 to 5, with a mean of 1.64. No differences were observed in the frequency of Q variants between sexes. The observed homo- and heteromorph frequencies always agreed with those predicted by the law of Hardy-Weinberg. Of the 157 subjects, four (2.55%) had pericentric inversion of the Q-heterochromatin band in chromosome 3. The following topics are discussed: (1) possible selective value of chromosomal Q-heterochromatin material in the adaptation of human populations to extreme environmental factors, in particular to cold; (2) the taxonomic value of chromosomal Q polymorphism in ethnic anthropology.     

Genetic differentiation in theAedes atropalpus complex. II. Chromosomal divergence betweenAe. atropalpus andAe. epactius

Analysis of meiotic chromosomes from hybrids betweenAedes atropalpus andAe. epactius has revealed that the two species are fixed for alternate arrangements of four inversions: a paracentric inversion of chromosome 1, two paracentric inversions of chromosome 2, and a pericentric inversion of chromosome 3. This chromosomal heterozygosity in the interspecific hybrids has resulted in extensive meiolic chromosomal asynapsis. Dicentric bridges, acentric fragments, and chromosomal breakage were also associated with the heterozygous inversions. This disruption of meiosis was sufficient to account for the partial sterility observed in interspecific hybrids. No chromosomal polymorphisms, aberrations, or reduction in fertility was observed in parental strains of intraspecific hybrids of the two species.     

Human chromosomal polymorphism. IV. Chromosomal Q polymorphism in Russians living in Kirghizia

Summary Chromosomal Q polymorphism was studied in 200 Russian individuals (94 females and 106 males) living in Kirghizia. Of the 200 individuals, 191 had chromosomal Q polymorphic variants, while nine (4.5%) had no Q bands with fluorescence levels 4 and 5. The mean number of Q variants per individual ranged from 0 to 7, with a mean of 2.9. There were no differences in the frequency of Q variants between sexes. The observed homo- and heteromorphic frequencies completely agreed with those predicted by the law of Hardy-Weinberg. Of the 200 individuals, 12 (6.0%) had pericentric inversion of the Q band in chromosome 3, one individual (0.5%) having a homomorphic form of this inversion. The possible selective value of chromosomal Q heterochromatin material in the adaptation of human populations to extreme environmental factors, in particular to cold, and the possible taxonomic value of inverted Q heterochromatin bands in chromosome 3 in ethnic anthropology, are discussed.