bluuebunny/crossref_metadata_2025 huggingface dataset:
Intra-species DNA polymorphism in the tobacco cyst  nematode complex (Globodera tabacum) using AFLP
Authors: Marché Laurent , Valette Sylvie , Grenier Eric , Mugniéry Didier
Published: April 2011

Amplified fragment length polymorphism (AFLP) was used to obtain information on the within-species genetic variability of the tobacco cyst  nematode (TCN) complex. AFLP was found to be well suited to this type of study. The current classification of TCN was confirmed. Results indicate that the Globodera tabacum solanacearum group, believed to be restricted to the U.S.A., also occurs in Mexico. The within-species variability of TCN is considerable. Populations from Mexico may form a new subgroup. AFLP group-specific markers were identified for two of the TCN subgroups: Globodera tabacum tabacum and Globodera tabacum solanacearum.Key words: Heteroderinae, classification, markers, genetic diversity, geographic distribution.
Cytology, RAPD, and seed colour of progeny plants fromBrassica rapa-alboglabraaneuploids and development of monosomic addition lines
Authors: Heneen W K , Jørgensen R B
Published: April 2011

Progeny plants from Brassica rapa-alboglabra aneuploids were characterized genetically by scoring random amplified polymorphic DNA (RAPD) markers and seed colour and cytologically as to chromosome number and pairing. Sets of RAPD markers specific for each of the encountered eight alien Brassica alboglabra chromosomes were defined. The finding of subsets of markers associated with the presence or absence of alien chromosomes inferred the frequent occurrence of intergenomic genetic recombination and introgression. The chromosome numbers were in the range 2n = 2028, with a maximum of seven alien B. alboglabra chromosomes and one trisomic B. rapa chromosome. Five types of monosomic addition lines were obtained, two of which have not been developed before. Differences in chromatin condensation patterns made it possible to differentiate between the B. rapa and B. alboglabra chromosomes at diakinesis, and to detect intergenomic homoeological pairing. In addition to the frequent formation of trivalents by homoeologous pairing of an alien B. alboglabra chromosome and a background B. rapa pair, occasional heteromorphic intergenomic bivalents and B. rapa univalents were encountered. Homoeological intergenomic pairing occurred between chromosomes with similar centromeric and karyotypic positions. Plants with structurally changed alien chromosomes were found. The RAPD and cytological data substantiated each other. Observations of the colour of sown and harvested seeds indicated that B. alboglabra chromosome 4 carries a gene for brown seed colour. It exerts its control embryonically, and thus it differs from chromosome 1 which controls seed colour maternally.Key words: Brassica rapa-alboglabra, monosomic addition line, chromosome homoeology, RAPD markers, seed colour.
Identification of a major gene and RAPD markers for yellow seed coat colour in Brassica napus
Authors: Somers Daryl J , Rakow Gerhard , Prabhu Vinod K , Friesen Ken RD
Published: April 2011

The development of yellow-seeded Brassica napus for improving the canola-meal quality characteristics of lower fibre content and higher protein content has been restricted because no yellow-seeded forms of B. napus exist, and their conventional development requires interspecific introgression of yellow seed coat colour genes from related species. A doubled-haploid (DH) population derived from the F1 generation of the cross 'Apollo' (black-seeded) × YN90-1016 (yellow-seeded) B. napus was analysed via bulked segregant analysis to identify molecular markers associated with the yellow-seed trait in B. napus for future implementation in marker-assisted breeding. A single major gene (pigment 1) flanked by eight RAPD markers was identified co-segregating with the yellow seed coat colour trait in the population. This gene explained over 72% of the phenotypic variation in seed coat colour. Further analysis of the yellow-seeded portion of this DH population revealed two additional genes favouring 'Apollo' alleles, explaining 11 and 8.5%, respectively, of the yellow seed coat colour variation. The data suggested that there is a dominant, epistatic interaction between the pigment 1 locus and the two additional genes. The potential of the markers to be implemented in plant breeding for the yellow-seed trait in B. napus is discussed.Key words: Brassica napus, yellow seed, RAPD.
Physical mapping of resistant and susceptible soybean genomes near the soybean cyst nematode resistance gene Rhg4
Authors: Lewers K S , Nilmalgoda S D , Warner A L , Knap H T , Matthews B F
Published: April 2011

The soybean cyst nematode (SCN), Heterodera glycines Ichinohe, is the foremost pest of soybean (Glycine max L. Merr.). The rhg1 allele on linkage group (LG) G and the Rhg4 allele on LG A2 are important in conditioning resistance. Markers closely linked to the Rhg4 locus were used previously to screen a library of bacterial artificial chromosome (BAC) clones from susceptible 'Williams 82' and identified a single 150-kb BAC, Gm_ISb001_056_G02 (56G2). End-sequenced subclones positioned onto a restriction map provided landmarks for identifying the corresponding region from a BAC library from accession PI 437654 with broad resistance to SCN. Seventy-three PI 437654 BACs were assigned to contigs based upon HindIII restriction fragment profiles. Four contigs represented the PI 437654 counterpart of the 'Williams 82' BAC, with PCR assays connecting these contigs. Some of the markers on the PI 437654 contigs are separated by a greater physical distance than in the 'Williams 82' BAC and some primers amplify bands from BACs in the mid-portion of the connected PI 437654 BAC contigs that are not amplified from the 'Williams 82' BAC. These observations suggest that there is an insertion in the PI 437654 genome relative to the 'Williams 82' genome in the Rhg4 region.Key words: BAC, deletion, insertion, resistance gene, soybean cyst nematode.
Efficient genetic transformation of Sorghum using a visual screening marker
Authors: Gao Zhensheng , Jayaraj J , Muthukrishnan S , Claflin Larry , Liang G H
Published: April 2011

To transform grain sorghum (Sorghum bicolor (L.) Moench) with a visual reporter gene (gfp) and a target gene (tlp), three genotypes (two inbreds, Tx 430 and C401, and a commercial hybrid, Pioneer 8505) were used. We obtained a total of 1011 fertile transgenic plants from 61 independent callus lines, which were produced from 2463 zygotic immature embryos via Agrobacterium-mediated transformation. The reporter gene, gfp, encoding green fluorescent protein (GFP), was used as a visual screening marker, and the target gene, tlp, encoding thaumatin-like protein (TLP), was chosen for enhancing resistance to fungal diseases and drought. Both genes were under the control of the maize ubi 1 promoter in the binary vector pPZP201. A total of 320 plants showing GFP expression, derived from 45 calli, were selected and analyzed by Southern blot analysis. There was a 100% correlation between the GFP expression and the presence of the target gene, tlp, in these plants. Transgenic plants showing strong TLP expression were confirmed by Western blotting with antiserum specific for TLP. The transgene segregated in various ratios among progeny, which was confirmed by examining seedlings showing GFP fluorescence. The progeny also showed different copy numbers of transgenics. This report describes the successful use of GFP screening for efficient production of stably transformed sorghum plants without using antibiotics or herbicides as selection agents.Key words: Agrobacterium tumefaciens, green fluorescent protein (GFP), sorghum transformation.
Chromosomal localization of rDNA in the Brassicaceae
Authors: Ali Hoda B.M , Lysak Martin A , Schubert Ingo
Published: April 2011

A survey is given about the number and chromosomal position of rDNA loci in 45 Brassicaceae species. For 34 species, 5S and 45S rDNA loci have been localized by two-colour fluorescence in situ hybridization for the first time. These data show the variability of rDNA within karyotypes of the Brassicaceae, provide anchor points for (comparative) genetic maps, and might be important for studies on concerted evolution of internal transcribed sequence types of rDNA in cruciferous plants.Key words: Brassicaceae, 5S and 45S rRNA genes, rDNA, FISH.
Salivary polytene chromosome mapping ofAnopheles(Cellia)subpictusGrassi (Culicidae: Diptera)
Authors: Chaudhry S , Neetu  , Gupta S , Chhilar J S
Published: April 2011

With the introduction of molecular taxonomy of mosquitoes, polytene chromosome maps have become indispensable as standard references for locating genes, puffs, and inversion breakpoints of unique DNA sequences. We present a line map and a photomap of the salivary polytene chromosomes of Anopheles (Cellia) subpictus Grassi, an important emerging vector of malaria in India. In addition, we discuss the nature of this species complex consisting of sibling species A, B, C, and D. The comparative study is in relevance to the X chromosome heterozygous inversion differences between 2 allopatric populations of the species and the recognition of 4 X-chromosome inversion genotypes viz: species A–X+a+b, B–Xab, C–Xa+band D–X+ab.Key words: Anopheles subpictus, polytene chromosome map.
Simple sequence in brain and nervous system specific proteins
Authors: Huntley Melanie A , Mahmood Sanaa , Golding G Brian
Published: April 2011

We examined sequences expressed in the brain and nervous system using EST data. A previous study including sequences thought to have neurological function found a deficiency of simple sequence within such sequences. This was despite many examples of neurodegenerative diseases, such as Huntington disease, which are thought to be caused by expansions of polyglutamine tracts within associated protein sequences. It may be that many of the sequences thought to have neurological function have other additional, non-neurological roles. For this reason, we examined sequences with specific expression in the brain and nervous system, using EST expression data to determine if they too are deficient of simple, repetitive sequences. Indeed, we find this class of sequences to be deficient. Unexpectedly, however, we find sequences expressed in the brain and nervous system to be consistently enriched for histidine-enriched simple sequence. Determining the function of these histidine-rich regions within brain-specific proteins requires more experimental data.Key words: amino acid repeats, homopeptides, simple sequence, triplet repeat diseases, nervous system proteins, brain-specific proteins.
Genome size is not related to life-history traits in primates
Authors: Morand Serge , Ricklefs Robert E
Published: April 2011

Genome size (C value, the haploid DNA content of the nucleus) varies widely among eukaryotes, increasing through duplication or insertion of transposable elements and decreasing through deletions. Here, we investigate relationships between genome size and life-history attributes potentially related to fitness, including body mass, brain mass, gestation time, age at sexual maturity, and longevity, in 42 species of primates. Using multivariate and phylogenetically informed analyses, we show that genome size is unrelated to any of these traits. Genome size exhibits little variation within primates and its evolution does not appear to be correlated with changes in life-history traits. This further indicates that the phenotypic consequences of variation in genome size are dependent on the particular biology of the group in question.Key words: age at maturity, body size, brain mass, C value, genome size, gestation time, life history, primate.
Transcriptome comparison of winter and spring wheat responding to low temperature
Authors: Gulick Patrick J , Drouin Simon , Yu Zhihua , Danyluk Jean , Poisson Guylaine , Monroy Antonio F , Sarhan Fathey
Published: April 2011

Freezing tolerance in plants is a complex trait that occurs in many plant species during growth at low, nonfreezing temperatures, a process known as cold acclimation. This process is regulated by a multigenic system expressing broad variation in the degree of freezing tolerance among wheat cultivars. Microarray analysis is a powerful and rapid approach to gene discovery. In species such as wheat, for which large scale mutant screening and transgenic studies are not currently practical, genotype comparison by this methodology represents an essential approach to identifying key genes in the acquisition of freezing tolerance. A microarray was constructed with PCR amplified cDNA inserts from 1184 wheat expressed sequence tags (ESTs) that represent 947 genes. Gene expression during cold acclimation was compared in 2 cultivars with marked differences in freezing tolerance. Transcript levels of more than 300 genes were altered by cold. Among these, 65 genes were regulated differently between the 2 cultivars for at least 1 time point. These include genes that encode potential regulatory proteins and proteins that act in plant metabolism, including protein kinases, putative transcription factors, Ca2+ binding proteins, a Golgi localized protein, an inorganic pyrophosphatase, a cell wall associated hydrolase, and proteins involved in photosynthesis.Key words: wheat microarray, expression profile, plant transcription, cold-regulated genes, freezing tolerance, cold acclimation, winter hardiness, stress genes, gene regulation, wheat transcriptome.
Heteroplasmy and paternally oriented shift of the organellar DNA composition in barley–wheat hybrids during backcrosses with wheat parents
Authors: Aksyonova Elena , Sinyavskaya Marina , Danilenko Nina , Pershina Lidia , Nakamura Chiharu , Davydenko Oleg
Published: April 2011

Mitochondrial (mt) and chloroplast (ct) genome inheritance was studied in barley–wheat hybrids, as were their progenies obtained from backcrosses with different common wheat cultivars, by monitoring the composition of 4 mtDNA (coxI, a 5′-flanking region of cob, nad3-orf156, and 5′-upstream region of 18S/5S) and 2 ctDNA (simple-sequence repeat locus downstream of trnS and a 3′-flanking region of rbcL) loci. In male sterile F1and BC1plants, maternal barley mtDNA fragments were mainly detected and very low levels of paternal wheat fragments were occasionally detected by PCR in coxI, a 5′-flanking region of cob and nad3-orf156, whereas a 5′-upstream region of 18S/5S showed clear heteroplasmy, containing both maternal and paternal copies, with maternal copies prevailing. Plants showing such heteroplasmic mtDNA composition remained either semisterile or became completely sterile in the later backcross generations. Only maternal ctDNA copies were detected in these plants. In 3 stable, self-fertile, and vigourous lines obtained in the advanced backcross generations and possessing recombinant wheat nuclear genome, however, only mt- and ctDNA copies of wheat parents were detected; thus, the original alloplasmic condition appeared to be lost. Our results suggest that transmission followed by selective replication of the paternal wheat organellar DNA leads to a paternally oriented shift of the organellar DNA composition in barley–wheat hybrids, which correlates with the restoration of fertility and plant vigour. These 2 processes seem to be related to nucleocytoplasmic compatibility and to be under the control of the nuclear genome composition.Key words: barley–wheat hybrids, ctDNA, mtDNA, nucleoytoplasmic compatibility, organelle DNA inheritance.
Molecular and cytological characterization of genomic variability in hexaploid wheat 'Lindström'
Authors: Costa-Nunes Pedro , Ribeiro Teresa , Delgado Margarida , Morais-Cecílio Leonor , Jones Neil , Viegas Wanda
Published: April 2011

'Lindström' wheat (AABBDD + rye B chromosomes) was used to study the effects of alien chromatin introgressed into a wheat genetic background, subjecting the wheat genome to a new and transient allopolyploidisation episode. Using this experimental material, we have previously demonstrated that no large-scale chromosomal translocations occurred as a result of the genomic constitution of the addition line. However, we have shown that the presence of a number of rye B chromosomes is associated with changes in the interphase organization and expression patterns of wheat rDNA loci. We have now extended our studies to focus on a further characterization of 'Lindström' 5S rDNA loci and also on high molecular weight glutenin subunit (HMW-GS) patterns. In the process, we have uncovered an unusually large variant of the 5S rDNA locus on wheat chromosome 1B (not to be confused with rye B chromosomes) and 2 novel HMW glutenin y-type alleles. These changes are not directly related to variation in rye B chromosome number in the present material, but the fact that a new, and still segregating, 1Dy HMW-GS gene was identified indicates a recent timescale for its origin. Strikingly, the 'Lindström' 5S rDNA 1B locus integrates a unit sharing 94% homology with a rye 5S rDNA sequence, suggesting the possibility that the wheat locus was colonized by highly homologous rye sequences during the breeding of 'Lindström', when the rye and wheat genomes were together, albeit briefly, in the same nucleus.Key words: Triticum aestivum 'Lindström', allopolyploidisation, 5S rDNA, NTS, high molecular weight glutenin (HMW-GS).
Mapping quantitative trait loci controlling agronomic traits in the spring wheat cross RL4452 × 'AC Domain'
Authors: McCartney C A , Somers D J , Humphreys D G , Lukow O , Ames N , Noll J , Cloutier S , McCallum B D
Published: April 2011

Relatively little is known about the genetic control of agronomic traits in common wheat (Triticum aestivum L.) compared with traits that follow Mendelian segregation patterns. A doubled-haploid population was generated from the cross RL4452 × 'AC Domain' to study the inheritance of the agronomic traits: plant height, time to maturity, lodging, grain yield, test weight, and 1000-grain weight. This cross includes the genetics of 2 western Canadian wheat marketing classes. Composite interval mapping was conducted with a microsatellite linkage map, incorporating 369 loci, and phenotypic data from multiple Manitoba environments. The plant height quantitative trait loci (QTLs), QHt.crc-4B and QHt.crc-4D, mapped to the expected locations of Rht-B1 and Rht-D1. These QTLs were responsible for most of the variation in plant height and were associated with other agronomic traits. An additional 25 agronomic QTLs were detected in the RL4452 × 'AC Domain' population beyond those associated with QHt.crc-4B and QHt.crc-4D. 'AC Domain' contributed 4 alleles for early maturity, including a major time to maturity QTL on 7D. RL4452 contributed 2 major alleles for increased grain yield at QYld.crc-2B and QYld.crc-4A, which are potential targets for marker-assisted selection. A key test weight QTL was detected on 3B and prominent 1000-grain weight QTLs were identified on 3D and 4A.Key words: height, lodging, mapping, maturity, microsatellite markers, test weight, 1000-grain weight, Triticum aestivum, wheat, yield.
RAPD markers encoding retrotransposable elements are linked to the male sex in Cannabis sativa L.
Authors: Sakamoto Koichi , Abe Tomoko , Matsuyama Tomoki , Yoshida Shigeo , Ohmido Nobuko , Fukui Kiichi , Satoh Shinobu
Published: April 2011

Male-associated DNA sequences were analyzed in Cannabis sativa L. (hemp), a dioecious plant with heteromorphic sex chromosomes. DNA was isolated from male and female plants and subjected to random amplified polymorphic DNA analysis. Of 120 primers, 17 yielded 400 to 1500-bp fragments detectable in male, but not female, plants. These fragments were cloned and used as probes in gel-blot analysis of genomic DNA. When male and female DNA was hybridized with 2 of these male-specific fragments, MADC(male-associated DNA sequences in C. sativa)3 and MADC4, particularly intense bands specific to male plants were detected in addition to bands common to both sexes. The MADC3 and MADC4 sequences were shown to encode gag/pol polyproteins of copia-like retrotransposons. Fluorescence in situ hybridization with MADC3 and MADC4 as probes revealed a number of intense signals on the Y chromosome as well as dispersed signals on all chromosomes. The gel-blot analysis and fluorescence in situ hybridization results presented here support the hypothesis that accumulation of retrotransposable elements on the Y chromosome might be 1 cause of heteromorphism of sex chromosomes.Key words: Cannabis sativa, FISH, RAPD, retrotransposon, sex chromosome.
Heterosis and genetic distance in rapeseed (Brassica napus L.): use of kinship coefficient
Authors: Lefort-Buson M. , Dattee Y. , Guillot-Lemoine B.
Published: April 2011

Different agronomic characters have been measured on F1 rapeseeds from inbred lines that are more or less related and on their parents, in Rennes (France). Two different experiments were conducted over a 2-year period. A study of the relationship between heterosis and genetic distance, measured here by a function of kinship coefficient (1–ψ), was carried out in two steps. First, four classes of increasing 1–ψ values were defined and related to heterosis value and F1 performance. The results point out a significant effect of the class, whatever the character and the year. Moreover, the best heterotic hybrids were always obtained with lines unrelated and coming from two different geographic pools. Then, the efficiency of 1–ψ for predicting heterosis or cross values was tested: it varies with year and character. For example, in the first experiment average relationship between lines was high, about 50% of seed yield variation owing to mean parent heterosis was explained with the 1–ψ distance.

Key words: heterosis, cross prediction, genetic distance, kinship coefficient, Brassica napus L.
Linkage studies in Tribolium castaneum (Herbst). XII. A revision of linkage group II
Authors: Sokoloff Alexander , Ferrone Robert F. , Chaney John D. , Braden Jerry , Muñoz Ricardo J.
Published: April 2011

Data are presented to show the linkage relationships of a number of genes in linkage group II of Tribolium castaneum and a revised map of this linkage group is presented bearing eight well-established points. Some of these points were establishable with the aid of an accidental inversion induced by gamma irradiation. Five additional mutants are also in this linkage group as a result of the revision, but their relative position needs to be established through additional linkage studies. The linkage map suggests the presence of two gene clusters, one affecting the eye color and morphology and the other including homeotic mutants that affect the morphology of the maxillary and labial palps, the thorax, and the abdominal sternites. Data are presented to show that the frequency of recombination for a number of segments in linkage group II is not equal in the two sexes. The literature bearing on the evolution of the karyotype in Tribolium is reviewed, and it is concluded, on the basis of the present evidence, that it is linkage group II and not linkage group IX that became translocated to the X and Y chromosome in a T. castaneum like ancestor to produce the much larger neo-X and neo-Y chromosomes of T. confusum.

Key words: Tribolium, linkage, gamma irradiation.
Cytogenetic study of three closely related species of Hawaiian Drosophila
Authors: Ahearn Jayne N. , Baimai Visut
Published: April 2011

Three allopatric species from the Hawaiian islands, Drosophila bostrycha (Molokai), D. affinidisjuncta (West Maui), and D. disjuncta (East Maui), are extremely similar in morphology but differ in metaphase chromosomes by the amount and distribution of heterochromatin. Their polytene chromosomes are virtually homosequential with only slight differences at the tip of the microchromosome. Each is polymorphic for one or more inversions, especially in chromsome 4. Salivary gland chromosomes of F1 larvae reared either from wild-caught females or wild-caught males mated to standard laboratory stocks were examined for gene arrangements. Drosophila bostrycha and D. affinidisjuncta share a polymorphism for inversion 4v, which is much more frequent in the latter than in the former. In D. disjuncta 4v has been found only joined in a haplotype with three other inversions (g2 h2 i2) at a low frequency at Kipahulu Valley. Drosophila disjuncta is unique in having another fourth chromosome inversion, 4k, which is highest in frequency at Waikamoi. A new inversion, 2s, was discovered at Uluini Stream. Interspecific hybridizations were carried out in small mass matings. Backcrosses and dissections demonstrated that all F1 females were fertile. All F1 males were sterile in either of two categories with reciprocal hybrids uniformly manifesting one or the other type. Attempts to model the sterility mechanism suggest that more than chromosomal sterility is involved. Our results are discussed in relation to other closely related clusters of species having heterochromatin-based karyotype variations.

Key words: heterochromatin, hybrid sterility, inversion, polymorphism, species divergence.
An autotetraploid model for genetic analysis of ozone tolerance in potato, Solanum tuberosum L.
Authors: Dragoescu N. , Hill Jr. R. R. , Pell E. J.
Published: April 2011

A genetic model for the analysis of descendants of two autotetraploid parents was developed and applied to genetic analysis of ozone tolerance in the potato (Solanum tuberosum L.). The model was developed for two alleles with chromosome segregation at a single locus and contained 13 parameters. Assumptions about the genotype of the parents were not required. A multiple regression approach was used to derive sums of squares associated with the different parameters. Additive genetic effects for ozone resistance were more important than nonadditive genetic effects in the descendants of two sets of crosses. Deviations from the genetic model were not significant in either cross. Digenic effects and parameters associated with a disequilibrium constant were the only other significant effects, but sums of squares owing to these effects were much smaller than those for additive effects. Generation means derived from the crosses indicated that part of the nonadditive effects may have been caused by inbreeding depression. An alternative model with only additive genetic effects and a parameter with the coefficient of inbreeding as the coefficient was evaluated. The alternative model did not fit the observed data as well as the original model.

Key words: ozone tolerance, potato, Solanum.
Chromosomal sex determination in aphids controlled by juvenile hormone
Authors: Hales Dinah F. , Mittler Thomas E.
Published: April 2011

Parthenogenetically reproducing aphids give birth to males in response to low temperatures and short photoperiods. Since female aphids are XX and males are XO, the apomictic production of male eggs requires the elimination of one of the X chromosomes. Our previous experiments had suggested that male eggs were produced when the concentration of juvenile hormone was low; we now confirm this by showing that the juvenile hormone analogue kinoprene prevents ovulation of male eggs in aphids whose corpus allatum has been destroyed by precocene. Juvenile hormone concentration thus influences the behaviour of the X chromosomes during the maturation division of the eggs, a high titre resulting in the retention of both X chromosomes and a low titre in the elimination of one of them.

Key words: sex determination, aphids, juvenile hormone, precocene, parthenogenesis.
Chromosome pairing at five ploidy levels in Elymus trachycaulus
Authors: Aung Taing , Walton P. D.
Published: April 2011

An autoallooctaploid (2n = 56) form of Elymus trachycaulus (Link) Gould ex Shinners (previously Agropyron trachycaulum (Link) Malte ex H. F. Lewis) was induced by treating allotetraploid shoots with 0.2% colchicine. Successive backcrossing to tetraploid pollen parents was successful and yielded five hexaploid (2n = 42), one pentaploid (2n = 35), and three hyperploid (2n = 31, 32, 33) plants. Metaphase I of the tetraploids was normal and 14 II chromosomes were observed, almost all of which were ring bivalents. Chromosome pairing in one octaploid, four hexploids, and one pentaploid were 4.38 IV + 0.65 III + 17.84 II + 0.85 I, 13.16 III + 0.84 II + 0.84 I, and 5.82 III + 8.18 II + 1.18 I, respectively. Efficiency of chromsome pairing (chiasmata per chromsome) was highest in tetraploids (1.29), lowest in hexaploids (0.75), and intermediate in both octaploid (0.95) and pentaploid (0.93) plants. The octaploid produced longer and broader leaves than the tetraploid, although the total dry matter produced was 14.3% lower. Total dry matter yield of the hexaploid was on an average 30.04% higher than the tetraploid and the leaves were significantly larger. The hexaploid plants were taller than both the tetraploid and the octaploid plants. Metaphase I pairing in hyperploid 1 (2n = 33) was 4.34 III + 9.66 II + 0.66 I, hyperploid 2 (2n = 32) was 2.98 III 11.03 II + 1.00 I; hyperploid 3 (2n = 30 + 1 t) was 1.97 III + 12.05 II + 0.66 I + 0.33 t. The pattern of chromosome pairing in these hyperploids suggest that they are a quintupal trisomic, a quadrupal trisomic, and a triple trisomic respectively. Backcrossing these hyperploids to euploid pollen parents was successful. Backosses and their progeny should result in a series of primary trisomiclines and some monosomic plants, which would be useful for gene mapping.

Key words: octaploid, hexaploid (double triploid), pentaploid, tetraploid, hyperploid, trisomic monosomic, Agropyron.
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.