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PubMed1991

Nucleotide sequence analysis of Adh genes estimates the time of geographic isolation of the Bogota population of Drosophila pseudoobscura.

The population of Drosophila pseudoobscura at Bogota, Columbia, is geographically and partially reproductively isolated from populations in the main body of the species in North America. The degree of genetic differentiation and time of divergence between populations at Bogota and Apple Hill, CA, were estimated by comparison of 3388 nucleotides in the alcohol dehydrogenase region (Adh and Adh-Dup genes) of 18 strains. Of the 146 polymorphic nucleotide sites detected, 68 and 31 were unique to the Apple Hill and Bogota samples, respectively, and 53 were shared. On the basis of an observed net divergence per nucleotide site of 0.264% between the two samples, the Bogota and North American populations were estimated to have been separated for at least 155,000 years. This divergence time suggests that D. pseudoobscura extended its range from North America to South America in a period of Pleistocene glaciation, when habitat suitable for the species presumably existed in lowland Central America.

Alcohol Dehydrogenase↗

PubMed1992

A dual level model for speciation by multiple pericentric inversions.

A considerable body of evidence suggests that the deleterious meiotic effects of pericentric inversions in F1 hybrids can be overcome by changes in chiasma location and various means of non-homologous pairing. Such overriding mechanisms may render pericentric inversions benign and increase the likelihood of their fixation in population isolates. It has been argued that overriding mechanisms of this type negate the involvement of pericentric inversions as reproductive isolating mechanisms in speciation. It is suggested, however, that the involvement of pericentric inversions in speciation should be considered on two levels. First, that by reducing meiotic effects in F1 hybrids, overriding mechanisms facilitate the fixation of pericentric inversions. Secondly, when contact hybridization occurs between the chromosomally derived and parental populations second-level effects may be encountered. That is, the recombinational effects of pericentric inversion differences on coadapted gene complexes (sensu Brncic, 1954, Shaw & Coates, 1983) enforce profound inviability barriers in F2 and backcross matings. In this way, multiple pericentric inversions may act as significant post-mating isolating mechanisms, whereas individual inversions with less significant second-level effects may not.

Animals↗

PubMed1988

[Analysis of the effects of oxytocin, vasopressin, angiotensin, serotonin and histamine on the blood flow in the reproductive organs of swine the during estrous cycle].

We have measured the magnitude of flow in the uterine artery (ua) and in ovarian artery (oa) in the isolated reproductive organs of pig (100-130 kg/per head) perfused with their own blood or Krebs-Henseleit's solution. The pressure was kept on the constant level 100 mm Hg. Were administered intraarterially Oxytocin (O), vasopressin (W), histamine (H), serotonin (5-HT) and hypertensin (A). Their possible influence on the processes of regulation of blood flow in the porcine reproductive organs during oestrus cycle was analysed. It was stated that O produced a decrease of blood flow (bf) in the periovulatory period (1-2 and 16-18 day of cycle). On the other hand doses many times bigger did not cause significant changes in ua in the luteal phase and in oa in all phases of the cycle. Action of O is connected with its pressing action on the uterine vessels, contracted by the smooth muscular coat of this organ. Limiting bf action of W and A is mainly connected with their direct vasoconstructive effect. Our results indicated that in physiological conditions during oestrous cycle O, W and A did not evoke significant changes in the regulation of blood flow in the porcine reproductive organs. High sensitivity of the investigated vessels on 5-HT in the luteal phase and lower sensitivity in the periovulatory phase could indicate serotonin's influence on the regulating changes of blood flow during oestrous cycle. Vessels of both investigated areas were very sensitive to H. Especially high sensitivity of oa vessels on H is correlated with an increase of sensitivity of the vessels on 5-HT and catecholamines in the luteal phase. It seem that H has significant importance as a factor antagonising influence of 5-HT and catecholamines in the luteal phase of cycle in the pig. Sensitivity of oa vessels on the investigated drugs was lower in all phases of the cycle studied than sensitivity of ua vessels, the only exception was when H was used. We observed similar reaction on used drugs, both in experiments with perfusion with the blood and with the Krebs-Henseleit's solution. It may suggest that vessels reaction depends upon the functional state of the organ and it is not directly connected with the hormones present in the blood.

Angiotensin II↗

PubMed1985

Symmetrical and asymmetrical sexual isolation among laboratory strains of Drosophila ananassae.

Male-choice experiments using five isofemale lines of Drosophila ananassae originating from different localities were performed to study sexual isolation within the species. In most of the crosses homogamic matings outnumber heterogamic ones, and deviation from randomness is statistically significant in 11 of 20 crosses. This provides evidence for positive assortative mating within D. ananassae. Isolation indices range from -0.057 to 0.555. Eleven positive isolation indices are significantly greater than zero. Both types of sexual isolation, symmetrical and asymmetrical, have been observed among different strains. Thus the present results clearly indicate that the laboratory strains of D. ananassae have developed behavioural reproductive isolation as a result of genetic divergence.

Animals↗

PubMed1991

Identification of a serum protein polymorphism via two-dimensional electrophoresis. Family and population studies in two genetically isolated groups: North American Hutterites and Australian aborigines.

We report the identification and initial family and population studies of a previously undescribed serum protein polymorphism with two allelic forms. It was discovered in Hutterites, a reproductively isolated religious sect, and is also present in Australian aborigines and a sample of Chicago residents. A two-allele model is consistent with the segregation pattern observed in five kindreds within our initial study group. This polymorphism, provisionally designated SPPM-158, appears as a horizontal (charge-based) doublet in silver-stained ISO-DALT high-resolution two-dimensional electrophoresis gels. It is a low-concentration polypeptide (approximately 1 mg/dL) that has an apparent MWSDS of 43.6 kD and an isoelectric point of approximately 5.5. We infer that it circulates as a multimer or in a high-molecular-weight (greater than 200 kD) complex with other proteins because it is not observed in normal body fluids derived from physiologically ultrafiltered plasma such as amniotic fluid, urine, or cerebrospinal fluid; however, it is present in urine of patients with glomerular proteinuria. The high heterozygosity rates imply utility of this new serum protein marker for both forensic and population studies.

Australia↗

PubMed1986

Inverted Y chromosome polymorphism in the Gujerati Muslim Indian population of South Africa.

An inverted Y chromosome has been found at a very high frequency in a Muslim Indian community living in the Johannesburg-Witwatersrand area of the Transvaal Province of South Africa: 8 of 141 (5.7%) retrospectively identified Indian males had an inv(Y)(p11.2q11.23) and all were of the Muslim faith. The inversion was found in 22 of 72 (30.5%) prospectively studied normal Muslim Indian males. All the carriers of the inversion were Gujarati-speakers whose families migrated to the Transvaal from the Gujerat Province of India during the first half of this century. The origins of the ancestors of the individuals with inv(Y) were traced to a small village, Kholvad, near the city of Surat, and some neighbouring villages. The polymorphic frequency of the inv(Y) has probably been produced through random genetic drift in a reproductively isolated community, maintained by strict endogamous marriage customs based on religious and linguistic affiliations. There was no indication that the inverted Y was associated with any reproductive disadvantages.

Black People↗

PubMed1977

The Cajuns of Southern Alabama: morphology and serology.

A survey was conducted of 324 members of the Cajun isolate of Southern Alabama. Tradition and appearance suggest that this population of about 3,000 are not entirely White, Black, or Indian but constitute a triracial community somewhat reproductively isolated and inbred. The earliest American settlement in the area, along the banks of the Mobile and Tombigbee Rivers, lay between Spaniards to the South and Indian tribes on the other sides: Creek, Choctaw, and Cherokee. Physical measurements are reported for 71 adults, plus color of skin, eyes, and hair. X-rays were taken of wrist and ankle bones of some 253 children. Red blood samples were typed on adults and children, and haptoglobin, Gm, and Gc types were determined from serum. History and physical examinations were also made. Physical measurements and observations suggest predominantly White ancestry, and D2 analysis confirms this, with least similarity to Indians. Analysis of serological traits implies almost 70% White, almost 30% Black, and very little Indians genes. Few defects of clear genetic etiology were discovered. Growth patterns judged from X-rays appeared normal. All genetic loci testable were in Hardy-Weinberg equilibrium except Gc. While history and some common surnames suggest endogamy in the past, the medical and serological findings, plus some additional surnames, indicate that the isolate has already been largely diluted or dissolved.

Adolescent↗

PubMed1989

Purification and properties of cyclic-3',5'-GMP-dependent protein kinase from the nematode Ascaris suum.

A cyclic-3',5'-GMP-dependent protein kinase was purified 7400-fold from the reproductive tract of female ascarids to a specific activity of 718 nmol min-1 mg-1 (histone as substrate). The yield of the preparation was 25%. The enzyme protein obtained was homogeneous as judged by isoelectrofocusing and polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. The native enzyme behaved as a dimer of two 82-kDa subunits in gel permeation chromatography on Superose 12. The protein kinase was inactive in the absence of cyclic purine nucleotides. Half-maximum velocity was obtained in the presence of 18 nM cGMP, whereas 400-fold higher concentrations of cAMP were required for the same activity. The enzyme underwent autophosphorylation in first-order kinetics (rate constant 0.054 min-1), leading to maximum incorporation of 0.96 phosphate per subunit. The autophosphorylation led to a 4-fold increase in Vmax, while the Km remained almost unchanged. In an extract from the reproductive tract, cGMP-stimulated phosphorylation was primarily observed in five proteins (molecular masses of 66, 60, 43, 30, and 25 kDa). These proteins also incorporated phosphate when isolated reproductive tracts were incubated in the presence of [32P]phosphate. The phosphate content in cellular proteins was enhanced when the incubation was performed in the presence of 10(-4) M of either octyl-cAMP or octyl-cGMP. In addition to the proteins mentioned above, however, six more electrophoretic bands containing radioactive phosphate were identified after in situ labeling of reproductive tracts with radioactive phosphate.

Animals↗

PubMedDate not supplied

Counter current transfer and back transport of 3H-PGF2 alpha in the cow's broad ligament vasculature ipsilateral and contralateral to the corpus luteum.

Eight cows of similar age (5-7 years) were chosen for the experiment. Isolated reproductive tract was supplied with autologous oxygenated and heated (40 degrees C) blood through the uterine artery and ovarian artery. 3H-PGF2 alpha in total dose of 2 MBq (10(7) cpm) was injected into each of the uterine lumen of isolated organ. Blood samples were collected at 5 min intervals during 120 min of experiment using cannulae inserted into the branches of uterine arteries about 1 cm below the horns and from ovarian arteries inserted 0.5 cm below the ovaries. The concentration of 3H-PGF2 alpha found in blood plasma taken from uterine artery or from ovarian artery on the side with active corpus luteum (CL) was significantly lower (p less than 0.001) compare with contralateral side to active CL. Radioactive PGF2 alpha found in branches of uterine arteries on both ipsilateral and contralateral side to CL was significantly higher (p less than 0.001) compare to ovarian artery of the same side. It is concluded that absorption of 3H-PGF2 alpha from uterine lumen into venous blood as well as its counter current transfer in area of broad ligament vasculature were reduced on the side of uterine horn with active CL probably as an effect of estrogen:progesterone ratio on vascular constriction in area of uterine vasculature.

Adnexa Uteri↗

PubMed1986

The heterochromatin of grasshoppers from the Caledia captiva species complex. I. Sequence evolution and conservation in a highly repeated DNA family.

The restriction enzyme TaqI digests 0.2% of the genomic DNA from the grasshopper Caledia captiva to a family of sequences 168 bp in length (length of consensus sequence). The sequence variation of this "Taq family" of repeat units was examined among four races from C. captiva to assay the pattern of evolution within this highly repeated DNA. The Taq-family repeats are located in C-banded heterochromatin on at least one member of each homologous pair of chromosomes; the locations range from centromeric to telomeric. Thirty-nine cloned repeats isolated from two population 1A individuals along with 11 clones from seven populations taken from three of the races demonstrated sequence variation at 72 positions. Pairwise comparisons of the cloned repeats, both within an individual and between different races, indicate that levels of intraspecific divergence, as measured by reproductive incompatibility, do not correlate with sequence divergence among the 168-bp repeats. A number of subsequences within the repeat remain unchanged among all 50 clones; the longest of these is 18 bp. That the same 18-bp subsequence is present in all clones examined is a finding that departs significantly (P less than 0.01) from what would be expected to occur at random. Two other cloned repeats, from a reproductively isolated race of C. captiva, have sequences that show 56% identity with this 18-bp conserved region. An analysis showed that the frequency of occurrence of an RsaI recognition site within the 168-bp repeat in the entire Taq family agreed with that found in the cloned sequences. These data, along with a partial sequence for the entire Taq family obtained by sequencing uncloned repeats, suggest that the consensus sequence from the cloned copies is representative of this highly repeated family and is not a biased sample resulting from the cloning procedure. The 18-bp conserved sequence is part of a 42-bp sequence that possesses dyad symmetry typical of protein-binding sites. We speculate that this may be significant in the evolution of the Taq family of sequences.

Animals↗

PubMed1976

Olfactory discrimination as an isolating mechanism in speciating mole rats.

Olfactory discrimination was tested in two chromosome forms of the speciating fossorial rodent, Spalax ehrenbergi, in Israel. Females of the chromosome forms 2n = 52 and 2n = 58 were tested for male odour discrimination, the source of odour being either case litter or urine. Estrous females of both forms preferred homochromosomal odurs, whereas diestrous females showed no discrimination. These results suggest that olfactory discrimination may serve as a reproductive isolating mechanism in the speciation of mole rats.

Animals↗

PubMed1992

Genetic distance and species formation in evolving populations.

We compare the behavior of the genetic distance between individuals in evolving populations for three stochastic models. In the first model reproduction is asexual and the distribution of genetic distances reflects the genealogical tree of the population. This distribution fluctuates greatly in time, even for very large populations. In the second model reproduction is sexual with random mating allowed between any pair of individuals. In this case, the population becomes homogeneous and the genetic distance between pairs of individuals has small fluctuations which vanish in the limit of an infinitely large population. In the third model reproduction is still sexual but instead of random mating, mating only occurs between individuals which are genetically similar to each other. In that case, the population splits spontaneously into species which are in reproductive isolation from one another and one observes a steady state with a continual appearance and extinction of species in the population. We discuss this model in relation to the biological theory of speciation and isolating mechanisms. We also point out similarities between these three models of evolving populations and the theory of disordered systems in physics.

Biological Evolution↗

PubMed1972

Hybridization between Aedes simpsoni and Aedes woodi with observations on the genetic basis of morphological differences.

The public health importance of the genus Aedes makes it imperative that a better understanding of the genetic differences and isolating barriers between the species be developed. Aedes simpsoni and Aedes woodi from near Dar es Salaam, Tanzania, were used in this investigation. Analysis of F(1), F(2), and backcross progeny obtained from forced matings indicates that single factors form the genetic basis of some of the differences between the two species. There is evidence that Ae. simpsoni and Ae. woodi are separated by both premating and postmating reproductive isolating mechanisms.

Aedes↗

PubMed1988

Mhc class II DNA polymorphisms within and between chromosomal species of the Spalax ehrenbergi superspecies in Israel.

Restriction fragment length polymorphisms (RFLPs) of two major histocompatibility class II genes (P alpha 1 and Q beta) were studied in 13 populations of four chromosomal species (2n = 52, 54, 58 and 60) of the mole rat, Spalax ehrenbergi superspecies in Israel. A substantial frequency of allelic fragments was found in both genes for all populations, including a desert isolate. In the P alpha 1 gene, one allelic fragment is a result of a deletion mutation which is diagnostic of the 2n = 52 chromosomal species. All other ten allelic variants are the result of point mutations. All mutations are located in a short region flanking the 3' end of the gene. Based on Mhc polymorphisms we confirm earlier evidence that gene flow does not occur between the older chromosomal species (2n = 52, 54, 58), and that reproductive isolation decreases, progressively from the oldest to the youngest species (2n = 60).

Animals↗

PubMed1992

[Descent of ova and embryos in cows superovulated with serum gonadotropin].

The descent and localization of eggs and embryos in individual segments of the reproductive tract of superovulated cows were studied in this work. For the induction of superovulation, serum gonadotropin (PMSG, Ivanovice in Haná) at a dose of 2,500-3,500 I.U. was used, in combination with 0.5 mg of Cloprostenol (Oestrophan, Spofa), administered 48 hours after gonadotropin treatment. The start of superovulation fell on days 9 to 12 of the sexual cycle and was conditioned by the presence of the corpus luteum (CL). After the onset of the heat, 2-3 inseminations were carried out using fresh semen. Donor cows were slaughtered 3, 4, 5, 6, and 7 days after the second insemination and isolated reproductive organs (Fig. 1) were divided into five segments (two on oviducts and three on uterine horns) by the applied ligature. In laboratory conditions superovulation response was determined accurately, the volume of ovaries was assessed according to water displacement and the segments of oviducts and uterus were rinsed with TCM 199 or PBS supplemented with FCS. 3, 4, 5, 6, and 7 days after insemination (Tab. I). 18.1 (+/- 3.55), 12.4 (+/- 0.91), 19.2 (+/- 2.86), 20 and 23 (+/- 2.44) CL on average were recorded, which corresponded to the ovulation of 64, 50, 56, 71 and 72 percent of stimulated follicles (Fig. 2). Within 3 to 7 days after insemination nearly triple enlargement of ovaries was also observed (Tab. I, Fig. 3). During the lavage of individual segments of the tubular reproductive tract, 38 per cent of eggs and embryos were detected in the uterus as early as 3 days after insemination (Tab. II). Unfertilized eggs and degenerated embryos were found in the 2nd and 3rd uterine segment, embryos at the stage of 8-16 blastomeres were localized in the 1st and 2nd segment of the uterus. Four days after insemination (Tab. III), about 64 per cent of eggs and embryos at the stage up to 16 blastomeres were found in the uterus, but embryos up to 32 blastomeres were still flushed out of the oviduct. On day 5 after insemination, 92 per cent of eggs and embryos were released into the uterus, being localized mostly in the cranial and medial part of the uterus (Tab. IV). 7.5 per cent of recovered eggs and embryos at the stage of early or compacted morulae were still detected in the oviducts.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1975

Allozymic and chromosomal similarity in two Drosophila species.

D. setosimentum and ochrobasis are a pair of very close, partly sympatric species endemic to Hawaii island. Males of the two species differ strikingly in wing-pattern and there are altitudinal and breeding-site differences. Similarity indices have been calculated for both chromosomal (C) ald allozymic (A) variants. Within the main populations of each species both kinds of data give coefficients above 0.98. Interspecific comparison of the main populations shows 0.66 (C) and 0.79 (A). An isolated population of ochrobasis from Kohala Volcano (Ohu), when compared with setosimentum, shows 0.68 (C) and 0.98 (A). Chromosomes are thus much more sensitive than allozymes in distinguishing these species; the same is true in the case of D. silvestris and heteroneura from the same forests. These morphologically distinct species, when compared, show 0.96 (A). All four species appear to be very new in the historical sense. In one area, about 2% of wild-caught D. setosimentum/ochrobasis are interspecific hybrids although adequate samples indicate that the separate gene pools have not broken down. The specific names should be retained but the two entities are perhaps best described as quite advanced semispecies in which reproductive isolation in nature is now nearly complete.

Animals↗

PubMed2014

Inter-genomic sexual conflict drives antagonistic coevolution in harvester ants.

The reproductive interests of males and females are not always aligned, leading to sexual conflict over parental investment, rate of reproduction and mate choice. Traits that increase the genetic interests of one sex often occur at the expense of the other, selecting for counter-adaptations leading to antagonistic coevolution. Reproductive conflict is not limited to intraspecific interactions; interspecific hybridization can produce pronounced sexual conflict between males and females of different species, but it is unclear whether such conflict can drive sexually antagonistic coevolution between reproductively isolated genomes. We tested for hybridization-driven sexually antagonistic adaptations in queens and males of the socially hybridogenetic 'J' lineages of Pogonomyrmex harvester ants, whose mating system promotes hybridization in queens but selects against it in males. We conducted no-choice mating assays to compare patterns of mating behaviour and sperm transfer between inter- and intra-lineage pairings. There was no evidence for mate discrimination on the basis of pair type, and the total quantity of sperm transferred did not differ between intra- and inter-lineage pairs; however, further dissection of the sperm transfer process into distinct mechanistic components revealed significant, and opposing, cryptic manipulation of copulatory investment by both sexes. Males of both lineages increased their rate of sperm transfer to high-fitness intra-lineage mates, with a stronger response in the rarer lineage for whom mating mistakes are the most likely. By contrast, the total duration of copulation for intra-lineage mating pairs was significantly shorter than for inter-lineage crosses, suggesting that queens respond to prevent excessive sperm loading by prematurely terminating copulation. These findings demonstrate that sexual conflict can lead to antagonistic coevolution in both intra-genomic and inter-genomic contexts. Indeed, the resolution of sexual conflict may be a key determinant of the long-term evolutionary potential of host-dependent reproductive strategies, counteracting the inherent instabilities arising from such systems.

Animals↗

PubMed1990

The genic nature of gamete eliminator in rice.

The two cultivated rice species, Oryza sativa and Oryza glaberrima, are morphologically alike but are reproductively isolated from each other by hybrid sterility. The hybrid is male sterile but partially female fertile. Backcross experiments were conducted to introduce an alien factor controlling hybrid sterility from O. glaberrima (W025) into O. sativa (T65wx) and examine the genetic basis. An extracted sterility factor, closely linked to the wx locus, induced gametic abortion due to allelic interaction and was tentatively designated as S(t). The segregation patterns for infertility was explained by assuming that W025 and T65wx carried S(t) and S(t)a, respectively, and gametes with S(t)a aborted only in the heterozygote (S(t)/S(t)a) although the elimination of female gametes was incomplete. Thus, S(t) seemed to be intermediate between a gamete eliminator and pollen killer. However, S(t) was proven to be likely the same as S1 which was formerly reported as gamete eliminator in a different genetic background of O. sativa. In addition, a chromosomal segment containing S1 (or S(t] caused a marked suppression of crossing over around it, suggesting the presence of an inversion. Further, female transmission of S1a increased as the segment containing S1 became small by recombination. After S1 was further purified by successive backcrosses up to the BC15 generation, it became pollen killer. The present results give evidence that a profound sterility gene such as gamete eliminator can be made from accumulation of pollen killer and its modifier(s) when pollen killer and modifier(s) are linked, they behave as a gene complex in the hybrid.

Alleles↗