bluuebunny/crossref_metadata_2025_split huggingface dataset:
A diallel cross in black spruce
Authors: Boyle T. J. B. 
Published: April 2011

A complete 7 × 7 diallel of black spruce (Picea mariana (Mill.) B.S.P.), without selfs, planted in three locations, was measured for height growth at several ages. Analysis using Griffing's method 3, model II, demonstrated that general combining ability (GCA) was the dominant genetic component of variation, although specific combining ability (SCA) appeared to be proportionately increasing in importance with age. When data from all locations were combined, the GCA × environment interaction proved to be highly significant. If the trend of increasing proportional importance of SCA continues, existing improvement strategies exploiting only GCA may need to be radically altered. Greater genetic gain would result from crosses among a few clones of high specific combining ability. Whatever approach is used, it appears likely that genotypes will have to be carefully matched to sites. Imbalance in the data set appeared to invalidate F-tests. As a result of heterozygosity in the parents and the likely presence of epistasis and linkage disequilibrium, the interpretation of GCA and SCA variance components in terms of additive and dominance genetic variance cannot be made. Key words: diallel cross, combining ability, black spruce, forest genetics.
Analysis of karyotypes and Giemsa C-banding patterns in eight species of Arachis
Authors: Cai Q. , Lu S. , Chinnappa C. C. 
Published: April 2011

The karyotypes and Giemsa C-banding patterns of the chromosomes in eight species of Arachis L. have been studied. Six species are diploid with 20 chromosomes and two are tetraploid with 40 chromosomes. One diploid species (A. rigonii Krap. et Greg.) belongs to the sect. Erectoides and the rest belong to the sect. Arachis. Among the diploid species from the sect. Arachis, A. batizocoi Krap. et Greg, has a unique karyotype while others have similar karyotypes. Two tetraploid species, A. monticola Krap. et Greg, and A. hypogaea L., possess the most similar karyotypes. However, the diploid species, A. rigonii, from sect. Erectoides, has a karyotype distinguishable from those in sect. Arachis. The C-banding patterns of the chromosomes have been obtained for all the species. The centromeric bands have been found in all the chromosomes and the intercalary bands can be identified in a varied number of chromosomes among these complements. However, the telomeric bands only exist in one or two chromosomes. The comparison of banding patterns demonstrated that structural differences exist among the chromosomal complements of the species with similar chromosome morphology. The karyotype variation among the different species and interspecific relationship are discussed. It is suggested that all the diploid species with the A genome are closely related. There are close relationships between the tetraploid species and diploid species with the A or B genome within sect. Arachis. Key words: Arachis, cytology, karyotypes, Giemsa C-banding.
The timing of first meiotic prophase in oocytes from female domestic dogs (Canis familiaris)
Authors: Freixa L. , García M. , Egozcue J. 
Published: April 2011

Meiotic studies in 15 female puppies (Canis familiaris) revealed that in this species first meiotic prophase begins postnatally. Leptotene is observed until day 5, zygotene from day 5 to day 15, pachytene from day 10 to day 30, diplotene from day 15 to day 30, and dictyotene appears by day 30. These results are not in agreement with previous reports on the timing of oogenesis in this species. Key words: Canis familiaris, oogenesis.
A comparison of the karyotypes of six species of Charadriiformes
Authors: Bartlett Sylvia E. , Threlfall William 
Published: April 2011

The embryonic tissue of three larid species (Larus argentatus, Larus marinus, Rissa tridactyla) and three species of alcids (Uria aalge, Alca torda, Fraterula arctica) were grown in vitro as primary explants to obtain mitotic chromosomes. Chromosomes that were harvested were stained with the fluorescent dye Atebrin. Partial karyotypes and idiograms of the largest 13 autosomes were made for each species. Based on the p arm to q arm ratios the centromere position for each chromosome was determined. Comparisons were then made between larid and alcid species as well as between groups (larid-alcid) and significant differences were noted. Key words: karyotypes, gulls, auks, Charadriiformes.
Effect of nullisomy for D-genome chromosomes and chromosome 5B on the cytological characteristics of pentaploid Triticum aestivum × T. dicoccoides hybrids
Authors: Ganeva G. , Bochev B. 
Published: April 2011

The effect of nullisomy for D-genome chromosomes and chromosome 5B on the meiotic behaviour of pollen mother cell chromosomes of pentaploid F1 hybrids of Triticum aestivum (cv. Bezostaya 1) × T. dicoccoides (Körn) was studied. The functional ability of female gametes with diverse chromosome constitution and the frequency of their inheritance in BC1 was assessed. Absence of individual T. aestivum D-genome chromosomes had a specific effect on meiotic chromosome pairing. The genetic systems involving chromosome 5B of the two species did not have the same effect on homologous and homoeologous chromosome pairing. Chromosome 5B of T. dicoccoides reduced bivalent pairing and increased multivalent associations. In BC1 the frequency of female gametes with n = 16–18 chromosomes was highest. Key words: nullisomy, chromosome pairing, Triticum, pentaploid hybrids.
Expression, inheritance, and linkage relationships among eight enzyme genes in Dermacentor albipictus (Packard) (Acarina: Ixodidae)
Authors: Hilburn Larry R. , Castillo Claudio 
Published: April 2011

Starch gel electrophoresis was used to examine the inheritance, expression, and linkage relationships among eight enzyme genes in the winter tick, Dermacentor albipictus. A fructose-specific hexokinase (FHK), adenylate kinase (ADK), and two forms of aconitase (ACON-A, ACON-C) appeared to have monomeric quaternary structures. A glycylleucine peptidase (PEP), isocitrate dehydrogenase (IDH), and anodally migrating malate dehydrogenase (MDH-A) were apparently dimers. The quaternary structure of glucose phosphate isomerase (GPI) could not be determined because of the similarity in relative mobility of the two available electromorphs. The genes for GPI, FHK, and ADK are located on the X chromosome in the following order: Adk – 37.4 – Gpi – 24.6 – Fhk, with Adk – Fhk being 46.5 map units apart. The remaining five genes were autosomally inherited. Of the 10 possible paired combinations of these genes, only the data for two pairs, Idh–Mdh (44.5% recombinants) and Acon-A–Acon-C (46.4% recombinants), suggested statistically significant linkage. Key words: enzymes, electrophoresis, Mendelian genetics, Dermacentor albipictus, tick.
Population cytogenetics of Chorthippus vagans. II. Reduced meiotic transmission but increased fertilization by males possessing a supernumerary chromosome
Authors: Cabrero Josefa , Camacho Juan Pedro M. 
Published: April 2011

A submetacentric B chromosome was present at a low frequency (ca. 4%) in a natural population of the grasshopper Chorthippus vagans. Its heterochromatic nature is shown by its positive heteropycnosis during first meiotic prophase and by its response to C-banding. As its C-banding pattern and the meiotic autopairing of its two arms both demonstrate, it appears to have been derived from a metacentric iso-B chromosome by means of a pericentric inversion. The frequencies of equational division of the B univalents and the formation of abnormal gametes were significantly different between the 2 one B males found. A causal relationship is demonstrated between the equational division of the B at anaphase I and the formation of spermatid micronuclei, which can be assumed to contain B chromosomes that are being eliminated. Such B elimination was higher in male no. 2 than in male no. 37. The estimated B-transmission frequency was 0.28 for male no. 2 and 0.46 for male no. 37. The presence in the same population of polymorphisms for the M4 and M7 autosomes made it possible to determine the specific parents for four egg pods containing the B chromosome produced in a mass culture using wild-caught individuals. From this we calculate the actual transmission of the B by the one B males to be 0.27 for male no. 2 and 0.44 for male no. 37, which agrees with their respective estimated transmission frequencies. The relative fitness of zero B and one B males was calculated in terms of their viability and fertility components. While viability was lower for one B individuals, their fertility was much higher than that of zero B males. Indeed, sexual selection in favour of one B males was sufficiently high to counteract both the reduced transmission of the B by one B males and the phenotypic selection against one B zygotes. Key words: Chorthippus, meiotic drag, supernumerary chromosome, B chromosome, sexual selection.
Variation in sex-linked interchange heterozygosity in the termite Incisitermes schwarzi Banks (Insecta: Isoptera) on the island of Jamaica
Authors: Luykx Peter 
Published: April 2011

Collections of colonies of the termite Incisitermes schwarzi from mangroves around the coast of Jamaica revealed six chromosomal types, all involving variations or rearrangements of the sex chromosomes. One of the types had a heteromorphic sex bivalent in which the Y chromosome was larger than the X. The other five races had complex interchange multiples: a chain of 11, a chain of 12, a ring of 12, a ring of 14, and a ring of 18 chromosomes. The situation is similar to that described previously for Kalotermes approximatus, another member of the family Kalotermitidae, in the southeastern United States. The different chromosomal types can be arranged in an evolutionary series, each step requiring an interchange or fusion between an autosome and a previously existing sex chromosome. Such polymorphic chromosome systems, containing Y-segregating elements of different evolutionary ages, may offer an unusual opportunity for studying the sequence of changes accompanying the evolution of Y chromosomes. Key words: termite, Incisitermes, sex-linkage, translocation, interchange, Jamaica.
Allozyme variability in natural populations of green alder (Alnus crispa) in Quebec
Authors: Bousquet J. , Cheliak W. M. , Lalonde M. 
Published: April 2011

Vegetative and sexual tissues from 22 populations of Alnus crispa (Ait.) Pursh (green alder, Betulaceae) in Quebec were analyzed for electrophoretically demonstrable diversity of 11 enzymes encoded by 16 structural loci in sexually mature populations. Of these 16 loci, 9 were found polymorphic. A total of 28 different alleles were detected with no more than three alleles per locus. No two-locus linkage disequilibrium was observed between eight polymorphic loci analyzed. Assuming a diploid model, average level of expected heterozygosity was 0.14 in the mature generation, with nearly all populations in Hardy–Weinberg equilibrium for the set of polymorphic loci investigated. Mean outcrossing rate was 0.95. Fixation indices revealed low inbreeding with no specific subpopulation structure. Hence, an important level of gene flow would exist within the populations. Without any strong evidence for polyploidy, and in the light of results obtained, the species could be classified equally well as a diploid or a diploidized allotetraploid. Key words: actinorhizal plant, alder, allozymes, Alnus, fixation indices, heterozygosity, outcrossing rate, polyploidy.
Segregation distortion of X-linked marker genes in interspecific crosses between Mus musculus and M. spretus
Authors: Biddle Fred G. 
Published: April 2011

An interspecific cross was made between females of the C3H/HeHa.Pgk-1a inbred laboratory strain of Mus musculus and males of the separate species Mus spretus. The F1 males are sterile but the F1 females are fertile and they were backcrossed to both C3H and spretus males. Evidence is presented from the segregation of X-linked marker genes that the interspecific F1female has a genetically deleterious effect on the C3H X chromosome that is expressed as a male-lethal effect with the spretus Y chromosome but not with the musculus Y chromosome of C3H. Key words: interspecific crosses, mouse, segregation distortion.
Production and cytogenetic analysis of hybrids between Triticum aestivum and some caespitose Agropyron species
Authors: Mujeeb-Kazi Abdul , Roldan Silverio , Suh D. Y. , Sitch Lesley A. , Farooq Shafqat 
Published: April 2011

Intergeneric hybrids between Triticum aestivum L. cultivars and 12 traditional Agropyron species were produced in variable frequencies, lowest being 0.35% for A. stipaefolium to a high of 41.98% for A. varnense. The crossing success of T. aestivum cultivars ranged from 'Chinese Spring' > 'Pavon-76' = 'Nacozari-75' > 'Fielder' = 'Fremont' > 'Glennson-81'. All F1 hybrids were somatically stable. The new combinations were with A. curvifolium (Thinopyrum curvifolium), A. rechingeri (T. sartorii = rechingeri), A. scythicum (T. scythicum), and A. stipaefolium (Pseudoroegeneria stipaefolia). All hybrids were perennial and possessed a modified phenotype that was intermediate between the parents involved in the hybrid combinations with major variation in spike morphology (elongated spikes with lax internodes). High-pairing hybrids, presumably owing to suppression of the Ph locus were of T. aestivum - A. scythicum (15.31 I + 2.25 II rings + 6.92 II rods + 0.32 III) and T. aestivum - A. stipaefolium (10.6 I + 7.08 II rings + 4.41 II rods + 0.54 III). In the other combinations, the pairing was either low or high, and if high, pairing was attributed to autosyndetic association of the alien genome chromosomes. Based on the meiotic pairing data, alien species that were segmental allotetraploids or partial autopolyploids, or segmental allohexaploids or autoallohexaploids, may be advantageous in developing backcross derivatives with synthetic genomes. Production of fertile amphiploids was restricted to T. aestivum - A. rechingeri. Key words: Triticum aestivum, Agropyron species, Pseudoroegeneria species, Thinopyrum species, intergeneric hybrids, crossability, wide crosses.
Chromosome pairing and aneuploidy in tetraploid triticale. I. Stabilized karyotypes
Authors: Lukaszewski Adam J. , Apolinarska Barbara , Gustafson J. Perry , Krolow K.-D. 
Published: April 2011

Among 38 lines of tetraploid triticale analyzed at meiosis, the number of paired arms per rye chromosome ranged from 1.14 to 1.76 and from 1.46 to 1.96 per wheat chromosome. The frequency of cells without univalents ranged from 22 to 90%. Pairing frequencies within rye and wheat genomes were correlated in all groups of lines. Lines without wheat chromosome 3B showed reduced pairing in both genomes, while lines with an additional pair of 5R chromosomes substituted for group-5 wheat chromosomes showed improved pairing of the rye genome but not of the wheat genome. In the rye genome, the chromosome arms that carry major blocks of telomeric heterochromatin paired with an average of 25.1% lower frequency than the arms without the telomeric heterochromatin, the difference being attributed to the difference in arm length and not to the presence of heterochromatic blocks. In the wheat genome, chromosome arms IBS, 5AS, and 5BS and chromosomes 4A and 7B paired with significantly lower frequency than the remaining arms of wheat chromosomes. Average aneuploid frequency in a sample of 1383 plants was 4.55%, with the mean value of 5.77% in lines with 14 wheat and 14 rye chromosomes, and 2.01% in lines with an extra pair of 5R chromosomes. The results indicate that while the meiotic pairing is poorer and aneuploid frequency is higher than previously believed, tetraploid triticales are nevertheless chromosomally much more stable than hexaploid or octoploid triticales. Key words: C-banding, heterochromatin, paired arms, chromosome substitution.
Interstitial chiasmata and centromere orientation in heterozygotes for a translocation in rye
Authors: Goicoechea P. G. , Roca A. , Naranjo T. , Giraldez R. 
Published: April 2011

The meiotic behaviour of plants heterozygous for translocation T242W of rye (involving 2RL and 6RL) and an interstitial C-band in 2RL has been analyzed. Chain and frying pan quadrivalents predominate. The following results have further been obtained: (i) double chiasmata occur in the interstitial segment carrying the C-band; (ii) from the frequency of being bound at metaphase I and the frequency of recombinant chromosomes at anaphase I, estimates of chiasma frequencies (and chiasma interference) in interstitial segments have been derived; (iii) estimates of the recombination fraction between the interstitial C-band and the translocation breakpoint have been obtained from offspring analysis; (iv) there is a difference in the frequency of alternate orientation between configurations with and without interstitial chiasmata (adjacent-2 has not been observed and a small but significant excess of alternate vs. adjacent-1 coorientation appears). Without intersitial chiasmata, alternate orientation predominates. The possible reasons for these differences are discussed. Key words: Secale cereale, translocations, chiasma frequency, centromere orientation.
Effect of Ph2 mutants promoting homoeologous pairing on spindle sensitivity to colchicine in common wheat
Authors: Ceoloni Carla , Feldman Moshe 
Published: April 2011

Two lines of common wheat cv. Chinese Spring carrying mutant alleles for the Ph2 homoeologous pairing-suppressor gene on chromosome arm 3DS promoting homoeologous pairing in wheat interspecific and intergeneric hybrids have been tested for their mitotic sensitivity to colchicine. Both the ph2a mutation, which corresponds to a fairly long deletion of 3DS, and ph2b, which is either an intragenic change or a very small deletion, as well as the ph2a/ph2b heteroallelic combination and the deficiency for the entire 3DS arm (ditelo 3DL), conditioned a significantly lower sensitivity to colchicine than that determined by the wild-type allele Ph2 (euploid and ditelo 3DS). Observation of both metaphase and anaphse root-tip cell populations, treated with various colchicine concentrations, provided similar results. The degree of spindle disruption in 2 × 10−4 M colchicine, as measured by the percentage of fully affected metaphases (C type), was significantly reduced in ph2 and Ph2− genotypes and, consequently, a larger proportion of cells could proceed toward anaphase and also had a regular segregation pattern at this stage. The differential sensitivity of ph2 genotypes to colchicine is in the opposite direction to that previously found for ph1 genotypes, lacking the homoeologous pairing suppressor on chromosome arm 5BL. The ph2 mutation, while promoting homoeologous pairing as ph1 does, decreases spindle sensitivity to colchicine with respect to the wild-type (ph2) allele rather than increasing it, as ph1 does. The observed alteration of spindle sensitivity to colchicine that mutants for structurally unrelated but functionally related genes (Ph1 and Ph2) condition is interpreted as a highly probable coincidence in their cellular target. It is assumed therefore that these loci affect the equilibrium between tubulin and microtubules. Through this effect they presumably determine chromosome positioning in somatic and premeiotic stages, leading to different pairing patterns at meiosis. Key words: Triticum aestivum, tubulin, pairing suppressors, somatic association.
The meiotic stage of preovulatory oocytes in mares
Authors: King W. Allan , Bezard Jacqueline , Bousquet Daniel , Palmer Eric , Betteridge Keith J. 
Published: April 2011

Confusion exists as to whether the oocytes of the domestic horse are ovulated at the first meiotic metaphase (MI) or the second (MII). In this study eight oocytes were collected from the preovulatory follicles of 16 mares 36 h after human chorionic gonadotropin CG treatment. Six of the eight oocytes were judged to be at MII by the presence of the first polar body and this judgement was confirmed by semithin sectioning in one. Of the two that had no polar body, one was found to be at MII after fixation for chromosomal analysis and the meiotic stage of the other remained undetermined. Since all seven oocytes yielding conclusive evidence were at MII, it was concluded that horse oocytes, like those of most mammals studied, are ovulated after completion of the first meiotic division and formation of the first polar body. Key words: horse, oocytes, ovulation, meiosis, chromosome.
Polyploidy in a natural population of mussel, Mytilus trossulus
Authors: González-Tizón A , Martínez-Lage A , Ausio J , Méndez J 
Published: April 2011

We have analyzed natural polyploidy in a population of Mytilus trossulus from Vancouver Island (British Columbia, Canada) by means of cytogenetic techniques. Results obtained are the first reporting on this type of numerical chromosome aberrations in mussels. Key words: mussel, Mytilus trossulus, polyploidy, chromosome.
Acute effects of methoxamine on left ventricular-arterial coupling in streptozotocin-diabetic rats: a pressure-volume analysis
Authors: Peng Ying-I , Chang Kuo-Chu 
Published: April 2011

We determined the acute effects of methoxamine, a specific alpha1-selective adrenoceptor agonist, on the left ventricular-arterial coupling in streptozotocin (STZ)-diabetic rats, using the end-systolic pressure-stroke volume relationships. Rats given STZ 65 mg·kg-1 iv (n = 8) were compared with untreated age-matched controls (n = 8). A high-fidelity pressure sensor and an electromagnetic flow probe measured left ventricular (LV) pressure and ascending aortic flow, respectively. Both LV end-systolic elastance ELV,ES and effective arterial elastance Ea were estimated from the pressure-ejected volume loop. The optimal afterload Qload determined by the ratio of Ea to ELV,ES was used to measure the optimality of energy transmission from the left ventricle to the arterial system. In comparison with controls, diabetic rats had decreased LV end-systolic elastance ELV,ES, at 513 ± 30 vs. 613 ± 29 mmHg·mL-1, decreased effective arterial elastance Ea, at 296 ± 20 vs. 572 ± 48 mmHg·mL-1, and decreased optimal afterload Qload, at 0.938 ± 0.007 vs. 0.985 ± 0.009. Methoxamine administration to STZ-diabetic rats significantly increased LV end-systolic elastance ELV,ES, from 513 ± 30 to 602 ± 38 mmHg·mL-1, and effective arterial elastance Ea, from 296 ± 20 to 371 ± 28 mmHg·mL-1, but did not change optimal afterload Qload. We conclude that diabetes worsens not only the contractile function of the left ventricle, but also the matching condition for the left ventricular-arterial coupling. In STZ-diabetic rats, administration of methoxamine improves the contractile status of the ventricle and arteries, but not the optimality of energy transmission from the left ventricle to the arterial system. Key words: streptozotocin-diabetic rats, left ventricular-arterial coupling, left ventricular end-systolic elastance, effective arterial elastance, optimal afterload.
HAEMOCYTES OF THE PACIFIC BEETLE COCKROACH, DIPLOPTERA PUNCTATA
Authors: Arnold J. W. 
Published: April 2011

AbstractHaemocytes of the Pacific beetle cockroach, Diploptera punctata (Esch.), are described and figured as they appear in vivo and in stained blood films. Although the haemocyte complex in this species is comprised of the same main categories as found commonly in other cockroaches, it is somewhat unusual due to morphological specialization among one category, the granular haemocytes. Most of the cells in this category are similar to those in other species, but some contain distinctive vesicles of mainly proteinaceous material, some are ovoid and contain spherule-size granules, and some are large, fusiform cells that are actively amoeboid in vivo. The other main categories, prohaemocytes, plasmatocytes, and spherule cells are fairly typical.