bluuebunny/crossref_metadata_2025 huggingface dataset:
GENERAL AND SPECIFIC COMBINING ABILITY IN SEVEN INBRED STRAWBERRY LINES
Authors: Aalders Lewis E. , Craig Donald L.
Published: November 2014

Seedlings of a diallel cross of seven strawberry inbreds omitting reciprocals were fruited in matted rows. Per acre fruit yields were comparable with leading cultivars, but berry appearance and quality of the hybrids were poor. Differences in resistance to powdery mildew reflected the values of the cultivars from which the inbreds were derived.All four characters studied showed significant general combining ability values, and three of the four showed significant specific combining ability values. These results are consistent with previous findings of considerable amounts of non-additive genetic variation in the strawberry.
STRUCTURAL HYBRIDITY IN A TUBEROUS SOLANUM HYBRID
Authors: Marks G. E.
Published: November 2014

A hybrid between S. morelliforme and S. clarum, both distinct diploid (2n = 2x = 24) Solanum species, is shown to be heterozygous for a chromosome interchange and possibly two inversions. This situation, common in some genera, is extremely rare in Solanum. In an F2 progeny of 13 plants 5 were interchange heterozygotes; all but one of the 13 showed failure of chromosome pairing despite having high chiasma frequencies. In three morphological and five biochemical characters scored, there was segregation in four cases, and of these, leaf index and flower number gave clear indications of transgressive segregation. Apart from flower color and an unidentified phenolic compound in the leaves, – both characters derived from S. clarum – all characters showed a dominant effect of S. morelliforme, the female parent.A single case of structural hybridity does not necessarily mean that chromosomal rearrangements have played a part in the differentiation of the parent species. It does, however, illustrate the point that the chromosomal mechanism necessary to reveal gross structural hybridity can exist in diploid Solanum species suggesting therefore that the regularity of chromosome behavior observed in species and in species hybrids does in fact reflect a true absence of gross structural hybridity.
LARVAL AGE AND THE PATTERN OF DNA SYNTHESIS IN POLYTENE CHROMOSOMES
Authors: Nash David , Bell John
Published: November 2014

It has been shown, by autoradiography using H3-thymidine, that the frequency of salivary gland cells where DNA synthesis covers the entire length of a specific polytene chromosomal segment (Chromosome II, 56F-60A, Drosophila melanogaster) drops off some time during the last day of larval life. The frequency of highly discontinuous DNA synthesis over the same region remains at about the same level until a stage closer to puparium formation, when all DNA synthesis stops.If a cycle of DNA synthesis, once initiated, goes to completion, then this finding indicates that the patterns of spatially continuous synthesis tend to occur early in the replicative cycle and that the terminal phases of the cycle involve highly discontinuous patterns of synthesis.
CHROMOSOME ABERRATIONS IN TRYPAN BLUE INDUCED TERATOGENESIS IN MICE
Authors: Joneja M. , Ungthavorn S.
Published: November 2014

Pregnant Swiss mice were injected with trypan blue on the 9th day of gestation. Analyses of anaphase-telophases revealed a high incidence of mitotic irregularities such as chromosome bridges, fragments or both, in the embryos. As a result of chromosomal rearrangements followed by mitotic aberrations, karyotypically abnormal cells were formed in the embryos and they had a relatively higher incidence of such abnormal cells than the untreated controls. This study does not suggest any direct causal relationship between chromosomal lesions induced and the teratogenic effects of trypan blue. However, it is possible that these aberrations are factors affecting the viability and proliferative capacities of the embryonic cells.
EVOLUTIONARY ORIGIN OF POA ANNUA L. IN THE LIGHT OF KARYOTYPIC STUDIES
Authors: Koshy T. K.
Published: November 2014

From a karyotype analysis of Poa annua (2n = 28) two large chromosomes, I and II, and one small chromosome, XIV, as well as three chromosome groups containing two, four and five chromosomes have been identified. From a comparison of the karyotype of Poa annua with that published of Poa exilis (2n = 14) and Poa supina (2n = 14), doubt is cast on the theory that Poa annua is an allotetraploid of the two latter diploid species. The three chromosomes of Poa annua that could be identified with certainty existed in homologous pairs, indicating that the species could have originated from Poa exilis or Poa supina and one other hitherto unidentified species. It is suggested that further work on the karyotype of diploid species might reveal further useful information on the evolutionary history of the species.
CHROMOSOME REARRANGEMENTS AFTER LOW X-RAY DOSES GIVEN TO SPERMATOGONIA OF MICE
Authors: Léonard A. , Deknudt Gh.
Published: November 2014

Male mice from the BALB/c strain were given whole-body irradiation at doses of 25, 50, 75 and 100 R of X-rays. Seventy days after irradiation the mice were killed, the testes removed and meiotic preparations were made using an air-drying method. Translocation configurations involving four chromosomes were the most frequent type recorded. The percentage of translocations increased regularly from 0.42 after 25 R to 1.96 after 100 R. The relationship between the X-ray dose and the rate of abnormal cells appears to be linear with a regression coefficient of b = 0.018960.
CYTOGENETIC, ECOLOGIC AND MORPHOLOGIC STUDIES IN BRAZILIAN FORMS OF PASPALUM DILATATUM
Authors: Moraes Fernandes M. Irene B. De , Barreto I. L. , Salzano F. M.
Published: November 2014

The somatic number, meiotic behavior, morphology and ecology of five forms of Paspalum dilatatum Poir are reported. The sexual type yellow anther (2n = 40) showed essentially regular meiotic behavior. The common form (2n = 50) presented 20 II and 10 I in about 85% of the cells studied at diakinesis and metaphase I. Pauciciliatum (2n = 40) and Uruguaiana (2n = 60) showed a wide range of chromosome configurations at these stages; finally, Torres presented uniformly 60 univalents. These results are compared with morphologic and ecologic data and some suggestions about the possible mode of origin of these forms are presented.
SPONTANEOUS CHROMOSOME ABERRATIONS INMELANDRIUM
Authors: Choudhuri Hiran C.
Published: November 2014

Chromosome aberrations were observed in root tip cells of Melandrium album. These aberrations were generally in the form of dicentric chromosomes involving bridge formation, ring chromosomes, fragments and elimination of acentric fragments from daughter nuclei. All the aberrations varied from 19.6 to 10.7 per cent in the first and second generation seedlings respectively. The chromosome irregularities and abortion of pollen grains (4.0 to 5.0%) are presumably due to gene mutation which has been enhanced in aged seeds.
THE DEMONSTRATION OF A SEX CHROMATIN BODY IN AMNIOTIC TISSUE OF THE SHEEP
Authors: Bruère A. N.
Published: November 2014

A method is described for the demonstration of a sex chromatin body in cells of the amnio-chorion of the sheep. The observation proved reliable over a trial of 50 preparations. The sex chromatin body was clearly demonstrable in preparations from foetuses weighing 50 grams to 2155 grams. This is the first recorded demonstration of sex dimorphism in tissue other than nerve cells of this species.
THE MEIOTIC BEHAVIOUR OF A NULLI-HAPLOID PLANT IN AVENA SATIVA L.
Authors: Gauthier F. M. , McGinnis R. C.
Published: November 2014

A nulli-haploid plant (2n = 20) was found in the progeny of an induced monosomic line of Avena sativa L. var. Rodney (2n = 6x = 42). At metaphase 1, the number of associations ranged from 1 to 6 with a mean frequency of 3.5. The pairing frequency can best be explained by the absence of a genetic system, similar to that of chromosome 5B in Triticum aestivum, which would control the diploidisation of hexaploid oats.Chromosomes were associated terminally with an occasional interstitial chiasma. Closed bivalents were rare, and the frequency of trivalent associations was low. This meiotic behaviour confirms the genetic evidence as to the homoeology of the three genomes of the hexaploid oats, but seems to indicate a great deal of structural divergence between them.It is suggested that the long sub-terminal chromosome 7 might carry the gene for diploidisation.
MEIOTIC CHROMOSOME ANALYSIS IN THE 42-CHROMOSOME POINSETTIA, EUPHORBIA PULCHERRIMA
Authors: Bempong M. A. , Sink K. C.
Published: November 2014

A meiotic chromosome analysis of the 42- chromosome poinsettia, Euphorbia pulcherrima Willd. ex Klotzsch, by examination of PMC's revealed multivalent types ranging from uni- to quinquevalents. Bi- and trivalents were most prevalent with multivalent associations in typical ring, chain, Y and cross-type configurations. Irregularities in chromosome separation during meiosis were observed for the first time in this species.
SOURCES OF FIELD IMMUNITY TO MILDEW (PODOSPHAERA LEUCOTRICHA) IN APPLE
Authors: Knight R. L. , Alston F. H.
Published: November 2014

The response to mildew of a range of Malus species is tabulated. Crosses of M. robusta and M. zumi with cultivated apple showed clear segregation in 1:1 ratios of field immune: susceptible plants. Crosses of resistant selections of M. platycarpa and M. hupehensis with cultivated apple gave only immune progeny in F1
STUDIES ON THE EFFECTS OF STEROIDS ON DNA SYNTHESIS OF HUMAN CHROMOSOMESIN VITRO
Authors: Kang Yung Sun , Kang Hyen Sam , Park Sang Dai
Published: November 2014

Tritiated thymidine and autoradiographic techniques were used to investigate the sequence and pattern of DNA replication of sex chromosomes in cultured human cells treated with progesterone and testosterone.The average frequencies of progesterone- and testosterone-induced chromatid aberration were 19 and 26% respectively, whereas that of spontaneous aberration was 2.5%. No chromosome aberrations were found in sex chromosomes of either sex. Aberrations were distributed throughout cells in both S and G2stages. The general production of aberrations increased with increases in the time between isotopic labeling and fixation. The mean duration of G2was over 3 hours in the control, over 4.5 hours in the progesterone-treated group and 4.75 hours in the testosterone group. Thus, G2time for human kidney cells treated with steroids was delayed about 1 to 2 hours.Striking asynchrony of DNA duplication in homologous X chromosomes in steroids-treated female cells was also observed at the end of the period. However, even in metaphases that incorporated thymidine-H3at 6 hours before fixation the hot-X was detectable. The Y chromosome in male cells showed a high percentage of labeling intensity with particularly heavy grains, differing from that of G group. Metaphases of female cells labelled at 6 hours before fixation in progesterone had an unlabeled, chromosome in the complement of moderately labeled cells. This unlabeled chromosome was also found in testosterone-treated cells prepared 10 hours after labeling and is presumed to be heteropycnotic X chromosome.
THE CHROMOSOMES OF AVENA MAGNA
Authors: Rajhathy Tibor , Sadasivaiah R. S.
Published: November 2014

The karyotype of the newly discovered tetraploid species A. magna was described and compared with that of the other tetraploid species. While one set of chromosomes of A. magna is very similar to that of the As genome of some of the diploids and to that of the A genome of the other tetraploids, the second set of A. magna is quite different from the second set (B) of the other tetraploids. Preliminary evidence suggests that A. magna is a truly rare species in the Mediterranean region.
MAPPING OF THE TRANSEC WHEAT-RYE TRANSLOCATION
Authors: Driscoll C. J. , Bielig L. M.
Published: November 2014

Lines possessing an isochromosome derived from the Transec translocation chromosome were isolated and crossed to known telocentric 4A stocks. From observations on chromosome pairing behaviours in these crosses it was determined that the left arm of chromosome 4A is involved in the translocation. The rye segment was located one crossover unit from the centromere of chromosome 4A by the telocentric linkage method.
HERITABILITY AND GENETIC CORRELATION OF SOLUBLE SOLIDS, BULB SIZE AND SHAPE IN WHITE SWEET SPANISH ONION
Authors: McCollum Gilbert D.
Published: November 2014

Heritability of size, shape and soluble solids content of bulbs in a White Sweet Spanish onion cultivar (Allium cepa L.) was estimated in two ways: (1) by calculating regressions of half-sib offspring on female parent, and (2) by calculating half-sib family intra-class correlations. Heritabilities of bulb weight and diameter were low (0 and 28%; 0 and 27%); bulb height, intermediate (45 and 48%); shape index and solids, high (89 and 62%; 79 and 82%). Phenotypic correlations among five variables were separated into additive genetic and environmental correlations. The data contain negative genetic correlations between solids and bulb size; if confirmed, such a relationship would be of concern to plant breeders when selecting onions for higher solids content.
CYTOGENETICS OF X-RAY INDUCED ANEUPLOIDS INARACHIS HYPOGAEAL.
Authors: Patil S. H.
Published: November 2014

Four mutant groundnuts, Arachis hypogaea L., carrying aneuploid chromosomes were isolated. Meiotic anomalies such as univalent formation, lagging and abnormal distribution of chromosomes were common to all. Cytomixis was observed in two of the mutants and these were sterile. The meiotic anomalies, however, did not affect the pollen fertility appreciably.The mutants were conspicuous by their large inflorescences. Their reduced vigor suggests that the addition of chromosome (s) exerts a deleterious effect.The extra chromosome in a fertile trisomic mutant carried the mutant characteristic and hence was easily identified in the segregating progenies.
POLYGENIC VARIATION IN THE UTILIZATION OF ARGININE AND LYSINE BY THE CHICK
Authors: Hutt F. B. , Nesheim M. C.
Published: November 2014

In continued tests of two strains of White Leghorns that had been bred for high requirement (HA) or low requirement (LA) of arginine, after 4 weeks on a basal diet containing only 0.9% of that amino acid, HA chicks of the fifth selected generation attained only 27.6% of the average weight of controls given ample arginine, but for chicks of the LA strain the corresponding figure was 83.5%.Reciprocal crosses between these two strains yielded F1generations in which utilization of arginine, (as measured by rates of growth on the test diet) was intermediate between those of the parent lines. Similarly, chicks from reciprocal backcrosses of F1birds to both parental strains were intermediate in performance between the F1and the parental line concerned.These results show that the difference between the HA and LA strains in utilization of arginine is polygenic.Activity of the enzyme arginase in the kidneys of chicks was inversely proportional to the rate of growth, and was about five times as high in the HA strain as in the LA strain. Chicks of the former line also showed higher levels of free lysine, which are believed to be responsible for the excessive activity of arginase in HA chicks. It is concluded that the selection practised differentiated two strains which differ in ability to thrive on a high-lysine, low-arginine diet.
MONOSOMICS OF KANOTA OATS
Authors: Nishiyama I. , Forsberg R. A. , Shands H. L. , Tabata M.
Published: November 2014

Twin seedlings, which often are polyploid or aneuploid, of Avena byzantina C. Koch var. Kanota were successfully used as a source of monosomics. Progenies of monosomic plants were grown in the nursery and were compared for frequencies of 40-, 41-, and 42-chromosome segregates, culm and panicle length, fertility, and certain other discriminating phenotypic characteristics. Monosome length and long-arm ratio, and ratio of 20- to 21-chromosome pollen based on univalent elimination were determined for each line. It is tentatively concluded that at least 12 or 13 different monosomic lines were identified among 17 lines studied. Nullisomics were found only among progenies in line Mk-9, a monosomic fatuoid. Awn development on nulli-, mono-, and disomics in this line suggests that genes in one or more chromosomes, in addition to those in the C chromosome, affect the inhibition of awn development.
METHOD OF SELFING F1CULTURES AND INTERPRETING GENETIC DATA IN RUST FUNGI
Authors: Miah M. A. Jabbar
Published: November 2014

The pooled nectar method of selfing F1rust cultures introduces sampling errors because of limited numbers (a) of pycnia selected, (b) of aecia sampled, (c) of cultures derived per aecium. The reciprocal method of selfing is more reliable. An improved method of calculating genetic ratios from the pooled nectar method of selfing is comparable to backcrossing and offers marked advantages over present methods.
THE HOMOEOLOGY OF AEGILOPS MUTICA CHROMOSOMES
Authors: Jones J. K. , Majisu B. N.
Published: November 2014

Chromosome pairing in Aegilops squarrosa × Ae. mutica hybrids was almost regular and exceeded the pairing in hybrids between Ae. mutica and Sitopsis species of Aegilops, and between Ae. mutica and diploid Triticum species. The Ae. mutica genome is homoeologous with the A, S(B) and D genomes present in wheat, and the evidence reported and reviewed does not suggest that this genome is homoeologous with the B genome of Triticum aestivum in particular. The chromosomes of Ae. mutica appear to have considerable homoeology with the D genome of Ae. squarrosa, and the general homoeology may indicate that it is an ancestral species in the Triticinae. Analysis of chromosome pairing in triploid hybrids supports the hypothesis that factors in Ae. mutica do not independently produce additional homoeologous pairing other than that permitted by the suppression of regulation.
CHROMOSOME STRUCTURE — A MODEL BASED ON DNA REPLICATION
Authors: Person Clayton , Suzuki David T.
Published: November 2014

A model of chromosome structure is proposed which assumes: (i) that DNA replication is accomplished via right-hand (RH) rotation; and (ii), that where replicating DNA segments arc very long RH-rotation will not proceed with absolute freedom. It is expected that inhibition of rotation in daughter molecules will lead to the formation of left-hand-individual (LH-I) coiling systems in the two daughter molecules. It is also expected that inhibition of rotation in the parental molecule will cause the LH-I coiled daughters to be held together in a right-hand-relational (RH-R) association. The interaction between LH-I and RH-R coiling is expected to cause separation of the daughter molecules. Multistranded DNA-containing structures are expected to show, in addition to the LH-I coiling heirarchies formed within individual strands, an RH-R coiling heirarchy formed by the complex as a whole. An LH-I coiling heirarchy was looked for, and found, in Cleveland's drawings of flagellate chromosomes. Evidence for the existence of RH-R coiling was also found. Results of electron-microscope studies on chromosome structure were briefly examined, as were the structures of lampbrush chromosomes, salivary chromosomes and "normal" chromosomes. These studies provided additional, though less direct, evidence in favor of the replication hypothesis and the predictions developed from it.
TRISOMIC TRANSMISSION INLOTUS PEDUNCULATUS
Authors: Chen Chi-Chang , Grant W. F.
Published: November 2014

Transmission of the extra chromosome was studied for four primary trisomic types of Lotus pedunculatus Cav., named Broad, Pointed, Narrow, and Small (trisomic for chromosomes 3, 4, 5 and 6, respectively). Despite the low frequency of transmission (average 9.2%), parental trisomics were recovered in all of the four trisomic types. No significant difference was found between pollen and ovule transmission. It was suggested that either there is no difference in germination and tube growth between the n and n + 1 pollen grains, or selection against the n + 1 male gametes in pollen germination and tube growth is balanced by the mechanism (s) selecting against the n + 1 female gametes. Although there were variations in transmission rate within the same trisomic types, the shorter extra chromosomes tended to be transmitted more frequently than the longer ones. This was interpreted as reflecting the degree of genic unbalance created by the extra chromosome in gametes and zygotes. The longer the extra chromosome, the greater would be the unbalance, and hence the less chance there would be for the n + 1 gametes and 2n + 1 zygotes to be viable. The trisomic types Small and Narrow produced a few unrelated trisomics in their progenies. It was considered that meiotic irregularities in these trisomic types could account for the production of such unrelated trisomics.
GENOME RELATIONSHIPS IN TETRAPLOID AVENA
Authors: Sadasivaiah R. S. , Rajhathy Tibor
Published: November 2014

Relationships between the A and B genomes of the tetraploid Avena species (A. magna excluded) and between these and the AS genome of the diploid A. hirtula and strigosa were studied in triploid (ASAB) and tetraploid (ASASAB) hybrids. Chromosome affinities were estimated on the basis of the karyotypes and the pairing behaviour of the chromosomes.The main findings were:1. The AS karyotype of the 2x and the A of the 4x species were identical and the chromosomes of the genomes A and B were similar. No difference was noticeable in the karyotypes of the 4x species studied. A nucleolar chromosome appeared from the B set in the 3x hybrids. It was concluded that the B genome is probably a modified form of A.2. All the chromosomes were capable of pairing in the ASAB and ASASAB hybrids. High degree of homology between the AS and A genomes was indicated by the high frequency of ring bivalents and ring-rod trivalents. The synaptic success of the B genome chromosomes (up to six trivalents) was interpreted as homoeology between the A and B genome chromosomes. The long chains (up to XII) suggested heterozygosity for numerous large segments.3. Attempting to resolve the conflict between homoeology and bivalent pairing in the 4x species, a diploidizing gene system, effective only in the homozygous condition, was assumed.4. The effect of multiple differences for large segments in the evolution of alloploids was briefly discussed.
CYTOLOGICAL STUDIES ON THE ORIGIN OF JOHNSON GRASS
Authors: Mouftah Samir P. , Smith J. D.
Published: November 2014

Observations were made at diakinesis and metaphase I of the frequencies of the various types of chromosomal associations in advanced generation allotetraploids of Sorghum vulgare × S. virgatum and in tri-species hybrids of (S. vulgare × S. virgatum)2 × S. halepense. The most frequent configurations were bivalents and quadrivalents, although all combinations from univalent to hexavalent were seen. Statistical analysis of the data failed to differentiate between the chomosomal behavior of the allotetraploids and that of the tri-species hybrids. This supports the hypothesis that S. vulgare and S. virgatum are the diploid progenitors of S. halepense.
INHERITANCE OF PALE COTYLEDON (PC) IN SWEETCLOVER
Authors: Goplen B. P.
Published: November 2014

A genetic analysis of P1, F1, F2 and BC1 in Melilotus alba revealed that the pale cotyledon trait was controlled by a single recessive gene, designated pc. This trait is characterized by chlorophyll-deficient cotyledons and normal green unifoliolate and subsequent trifoliolate leaves. Mature plants are indistinguishable from normal green sibs. The consistent deficiency of recessive F2 segregates was attributed to reduced vigor and differential seedling survival of the pale cotyledon segregates.
NATURAL SELECTION IN A COMPOSITE CROSS OF BARLEY
Authors: Singh L. N. , Johnson L. P. V.
Published: November 2014

A composite of 105 crosses involving 15 parental barley varieties was grown for 5 years at nine stations of widely different latitudes in Canada, U.S.A. and Norway. A resulting sample of seed was recovered from each station and grown with original seed in comparative studies at Edmonton. Significant differences were observed among plants from different stations for heading date, maturity period, yield, spike type, and awn type. Little difference was observed for plant height and seed size. There was little or no effect on collar type, neck shape, neck length, leaf width or shape of basal rachis internode. Natural selection acted strongly against black kernel, the elimination of which was probably due to genetic linkage with a character of low competitive capacity. In general, the shift in the gene pool was consistent with plant breeding objectives.
COCCIDIOIDES IMMITIS: CYTOLOGICAL STUDY ON THE FORMATION OF THE ARTHROSPORES
Authors: Kwon-Ciiung Kyung Joo
Published: November 2014

Somatic nuclear division and the manner of arthrospore formation in saprophytic phase of Coccidioides immitis have been studied. Two distinct nuclear cycles, one occurring during the active growth in young hyphae and another occurring in old thin hyphae or during arthrospore formation, were observed. The first cycle consisted of several stages starting from round resting nuclei → ring stage → V stage → and filaments which divide longitudinally. The two daughter nuclear filaments reorganize into round nuclei. The second cycle is more simple than the first. The round resting nuclei become elongated and constricted at the middle, dividing vertically. The chromosome number appears to be 3. The metaphase plares or spindle apparatus were not seen.The fertile hyphae develop septa not basipetally but synchronously. Alternate cells, after being thus delimited, increase in size and in thickness of wall becoming spores while the intervening cells gradually lose cytoplasm. The nuclei remain, without cytoplasm, in the intervening cells until the adjacent spores are completely matured. The spores are released by fragmentation of the walls of the sterile segments. The relationship of C. immitis to the members of Gymnoascaceae has been discussed.
MORPHOLOGICAL AND MEIOTIC CHARACTERISTICS OF THE EXTRACTED AABB TETRAPLOID COMPONENT OF THREE VARIETIES OF COMMON WHEAT
Authors: Kaltsikes P. J. , Evans L. E. , Larter E. N.
Published: November 2014

The extracted AABB component of three varieties of common wheat (Triticum aestivum L. em. Thell.) did not resemble presently grown varieties of durum wheat (T. turdigum var. durum). Relative to their corresponding hexaploid, the extracted AABB tetraploids exhibited reduced vigour, finer leaves, smaller and denser spikes, almost identical seed color, shorter stature, delayed maturity, and, with one exception, produced fewer tillers per plant. The three extracted tetraploids exhibited normal meiotic behaviour and pollen fertility.
THE CYTOGENETIC STATUS OF AVENA MAGNA
Authors: Rajhathy Tibor , Sadasivaiah R. S.
Published: November 2014

The corresponding pairing behaviour of the chromosomes of A. magna and A. abyssinica was determined in triploid and pentaploid hybrids. Much higher overall pairing was found in the A. abyssinica than in the A. magna triploids indicating reduced homology between the A genomes of the diploids and A. magna and the absence of homoeology between the A genome and the second genome of A. magna. In contrast, pairing was much higher in the A. magna pentaploid than that of A. abyssinica. It was concluded that the second genome of A. magna is closely related to one genome other than the A of the hexaploids. On the ground of morphology, cross-compatibility and the pairing behaviour of chromosomes it was proposed that A. magna has the genomes AADD and that it is the putative ancestral tetraploid of the hexaploid species. This hypothesis can be tested by a synthetic allohexaploid derived from A. ventricosa and A. magna.
DURATION OF MITOTIC CYCLE AND REGULATION OF DNA REPLICATION INNICOTIANA PLUMBAGINIFOLIAAND A HYBRID DERIVATIVE OFN.TABACUMSHOWING CHROMOSOME INSTABILITY
Authors: Gupta S. B.
Published: November 2014

The duration of the mitotic cycle with its component phases in Nicotiana plumbaginifolia (pbg, 2n = 20) and a hybrid derivative of N. tabacum (tbc, 2n = 48 and N. plumbaginifolia was determined from the root tips. A 30 minute pulse label of H3-thymidine was employed for the autoradiographic detection of the labeled prophases.The time intervals, for the total generation time (T), postsynthetic phase (G2), prophase, synthetic phase (S), and the combined presynthetic phase, metaphase, anaphase, telophase (G1 + M + A + T) in N. plumbaginifolia were estimated as 11.0, 3.4, 1.3, 5.7 and 0 6 hours, respectively. In the hybrid derivative the corresponding estimates were 9.0, 1.4, 0.8, 3.8 and 3.0 hours.The G1, S and G2periods of N. plumbaginifolia were found significantly different from those of the hybrid derivative, but the duration of the mitotic cycle did not show a significant difference. On the basis of the distribution of heterochromatin and its late replication in N. plumbaginifolia chromosomes, possible causes of instability of alien pbg chromosomes in N. tabacum nuclei are discussed.
HERITABILITY ESTIMATES AND INTERRELATIONSHIPS AMONG AGRONOMIC TRAITS IN GRAIN SORGHUM, SORGHUM BICOLOR (L.) MOENCH
Authors: Liang George H. L. , Walter T. L. , Nickell C. D. , Koh Y. O.
Published: November 2014

Heritability was estimated for 12 agronomic traits in two segregating grain sorghum populations in F3 and F4 generations by parent-offspring regression, parent-offspring correlation, and variance component methods. Half bloom, leaf number, and plant height were most heritable in both populations; head number was least heritable. Grain yield, head weight, kernel number, peduncle diameter, germination percentage, and threshing percentage had medium heritability values. Kernel weight and protein percentage were highly heritable in one population but less heritable in the other.Estimates of genetic correlations showed grain yield positively and strongly correlated with head weight, kernel number, half bloom, leaf number, and plant height, but negatively correlated with germination and protein percentages.Selection indexes constructed using various combinations demonstrated that selecting for yield could be more efficient if combinations other than or in addition to yield were utilized. Selection indexes were less effective in selecting for protein when protein was not included in the index.
THE SOMATIC KARYOTYPES OF AMERICAN BISON AND DOMESTIC CATTLE
Authors: Bhambhani R. , Kuspira J.
Published: November 2014

Established karyotypes for bovines are generally lacking and therefore necessitate at least a preliminary arbitrary system of nomenclature. The somatic karyotypes of two bovines (American bison and domestic cattle) were determined utilising a peripheral-blood culture technique. On the basis of a karyotype comparison, the cytotaxonomic relationship between the bison and the domestic cattle is stressed. A preliminary arbitrary system of nomenclature for bovine chromosomes has been suggested. It is hoped that further similar investigations will enable the establishment of a uniform system of nomenclature for bovine chromosomes.
STUDIES OF NATURAL POPULATIONS OFMUS. V. A SURVEY OF NINE LOCI FOR POLYMORPHISMS
Authors: Petras M. L. , Reimer J. D. , Biddle F. G. , Martin J. E. , Linton R. S.
Published: November 2014

An examination of house mice (Mus musculus) from a number of sites in southwestern Ontario revealed six loci (Hbb, Es-2, Es-3, Es-5, Ldr-1 and A) to be polymorphic and three (Es-1, Pro-1 and Trf-1) to be monomorphic. A comparison of the Ontario samples with samples from southeastern Michigan suggests that the polymorphisms detected are common to Mus populations in both regions and are relatively stable. Data reported by other investigators suggest that some of these polymorphisms have a broad geographic distribution. Also discussed are findings of loci described elsewhere. Two of these T and Ea-1, are polymorphic in some of the populations under consideration. General conclusions include: (1) that polymorphic loci are probably as frequent in mouse populations as in Drosophila and man; (2) that the polymorphisms observed are relatively stable and widespread; (3) that some of the alleles responsible for the polymorphisms observed are not neutral; and (4) that additional data are necessary to elucidate the mechanisms responsible for the polymorphisms observed.
MEIOSIS IN HYBRIDS BETWEEN BETA VULGARIS AND BETA COROLLIFLORA AND TRANSMISSION OF RESISTANCE TO CURLY TOP VIRUS
Authors: Savitsky Helen
Published: November 2014

An F1 tetraploid hybrid between 4n sugarbeet and 4n B. corolliflora, highly resistant or immune to curly top virus, was obtained by V. Savitsky. The b1 and b2 hybrid generations were produced by pollinating with diploid sugarbeets. The b1 plants were triploid or triploid-ancuploid. Sufficient fertility in the vulgaris-corolliflora hybrids was obtained by the introduction of a complete diploid set of B. vulgaris chromosomes into the F1 and b1 generations.These vulgaris-corolliflora hybrids are amphidiploids, i.e., pairing of chromosomes, as a rule, is autosyndetic between identical genomes (genomes belonging to the same species). In meiosis of 3n b1 hybrids, nine B. vulgaris bivalents and nine B. corolliflora univalents were formed. Occasionally, one or two trivalents were observed. Meiosis was quite regular; many univalents were transferred to the poles and included in the interkinetic nuclei.First and second backcross hybrids were inoculated with the curly top virus and selected for resistance. Highly resistant and apparently immune b2 hybrids were selected. They had two to seven B. corolliflora chromosomes in addition to the diploid set of B. vulgaris chromosomes. Resistance was due to genes on the B. corolliflora univalents.
POST-TREATMENT TEMPERATURE EFFECTS ON MUTATION FREQUENCY IN EMS-TREATED BARLEY
Authors: Satpathy D. , Arnason T. J.
Published: November 2014

Mutations continued to be induced in barley seeds for some hours after the seeds were transferred from EMS solution to water. Evidence for this was obtained by determining mutation frequencies in plants grown from different batches of seeds that had been treated in identical fashion except that they were subjected to different temperatures during a 12- or 24-hour washing period. Chlorophyll mutation frequencies were lowest after washing at 10 °C. With each 10 °C step up (to a maximum of 40 °C) mutation frequencies increased by 1.4-2.5 × provided that the mutation frequency after 10 °C post-treatment was well below the maximum obtainable with EMS. The effects of temperature during the treatment and post-treatment periods on mutation rate are similar in direction and in amounts. During the post-treatment period mutations probably continue to be induced for more than 12 hours since the frequencies were affected more by a 24-hour than by a 12-hour post-treatment temperature exposure. The effects are probably produced by altered rates of alkylation of DNA by EMS at different temperatures.
GENETIC CONTROL OF FLANKING MARKER BEHAVIOUR IN AN ALLELIC CROSS OF NEUROSPORA CRASSA
Authors: Thomas P. L. , Catcheside D. G.
Published: November 2014

Histidine-1 prototrophs of Neurospora crassa obtained from crosses between the alleles K83 and K625 were classified for combinations of the flanking markers inositol and amination-1. Comparison of the results from rec-1 × rec-1 and rec-1 × rec-1+ crosses shows that there is a marked change in the proportions of the two parental classes, from 1.51:1 to 0.55:1, but none in the proportions of the two recombinant classes. Analysis of 69 progeny of a rec-1 × rec-1+ cross failed to show segregation of the rec-1 locus from any factor affecting the distribution of flanking markers among his-1 prototrophs. The rec-1 genes are presumed to influence the point of origin, with respect to the his-1 locus, of hybrid DNA.
NUCLEOPROTEIN SYNTHESIS IN THE MITOCHONDRION
Authors: Lindegren Carl C. , Zink John M.
Published: November 2014

Lipolated (fat-filled) mitochondria in Saccharomyces have been observed both by light-microscopy and by electron-microscopy. Previous workers have shown, by ultraviolet-microscopy and by fat stains, using the light-microscope, that the lipolated mitochondria contain both lipids and ribonucleotides. The lipolated mitochondria are in close contact with the vacuolar membrane and presumably mediate the transfer of ribonucleotides from the nucleolus to the cytoplasm while fat supplies the energy for the synthesis of ribonucleoprotein in the mitochondrion.
INHERITANCE OF RESISTANCE TO NET BLOTCH IN BARLEY. I. FACTORS AFFECTING THE PENETRANCE AND EXPRESSIVITY OF GENE(S) CONDITIONING HOST RESISTANCE
Authors: Khan T. N.
Published: November 2014

Variability in the host-reaction of barley to infection by Drechslera teres was examined in the parents and progeny of selected crosses under different environmental conditions of testing.The Ethiopian variety C.I. 5791 exhibits a consistently high level of resistance under a range of environmental conditions, which is in contrast to the Manchurian variety C.I. 2330. The sensitivity of the genes for resistance possessed by these varieties to environmental modifications is considered to depend upon their respective genetic backgrounds. Furthermore, variability of host reaction in the progeny of these resistant varieties was shown to be influenced by the genetic background of the susceptible parent used.The implications of these findings in the conduct and interpretation of genetic studies and in backcross breeding programs is discussed.
'SNORTER' DWARFISM IN THE BOVINE
Authors: Benjamin B. R. , Stringam E. W.
Published: November 2014

An examination of the karyotypes of female homozygous normals, homozygous dwarfs of the 'snorter' type, and heterozygotes in Hereford cattle, using the leucocyte culturing technique, revealed no differences between the three. The karyotypes of an unclassified group of phenotypically normal males were similar except for the male determining chromosome. The latter was clearly shown in the karyotypes to be of the submetacentric X type and about [Formula: see text] the size of the larger X type chromosomes.
CYTOGENETIC EFFECT OF CHEMOSTERILANTS IN HOUSE FLY SPERM: INCIDENCE OF POLYSPERMY AND EXPRESSION OF DOMINANT LETHAL MUTATIONS IN EARLY CLEAVAGE DIVISIONS
Authors: LaChance Leo E. , Leopold Roger A.
Published: November 2014

The treatment of male house fles with sterilizing doses of tepa, hempa, or several intermediate analogs before mating with untreated females did not greatly reduce the number of eggs that were fertilized. However, in comparison with the controls the number of sperm entering the egg was significantly different in eggs fertilized with sperm from males treated with tepa, hempa, and three analogs. Because of the normal occurrence of polyspermy, the possible inactivation of sperm by the chemosterilants would not be as evident in a polyspermic insect as in a monospermic species.The cytological examination of the embryonic chromosome abnormalities produced by the chemicals revealed that all test chemicals resulted in the formation of chromosome bridges and fragments during early embryogenesis. These genetic abnormalities led to other developmental abnormalities and caused cessation of embryonic development. Although the chemicals differ structurally, all eventually produced similar cytogenetic damage, but there was evidence of some variation in the time of expression and distribution of the various kinds of cytogenetic aberrations produced by the various chemicals.
INTERACTING EFFECTS OF SODIUM MONOHYDROGENARSENATE AND SELENOCYSTINE ON CROSSING OVER IN DROSOPHILA MELANOGASTER
Authors: Walker G. W. R. , Bradley Amelia M.
Published: November 2014

Drosophila melanogaster females of X chromosome genotype y cυ υ f/++++ were reared as larvae on 16-treatment media, representing the various combinations of four concentrations each of sodium monohydrogen arsenate and selenocystine (concentrations were 0, 2, 10 and 50 μM). The fourfold replication of selenocystine curves at four arsenate levels confirmed the existence of a selenocystine effect indicated earlier (Ting and Walker, 1969), as well as the segmental differences in and reversibility of the effect. A marked "sink" in crossing over was found both in total single exchange chromosomes and total double exchange chromosomes at 10 μM selenocystine and peaks in single exchange for segment 1 and for the whole chromosome and for double exchange for segments 1 and 2 at 2 μM were noted. In addition, arsenate was shown to exert a marked effect in the selenocystine-concentration region 0-10 μM; crossover frequencies were quite consistently increased by arsenate treatment at zero selenocystine, and considerable differences were introduced into the initial region (0-2 μM) of selenocystine segmental curves by arsenate treatment, with resultant increases in total single exchange and double exchange curves. In addition, the general effect was noted in arsenate-concentration curves, at 2 and 10 μM As: a drop in double exchange and an increase in single exchanges. Hypotheses are presented relating these effects to possibilities regarding the incorporation of selenocystine and arsenate into chromosomal protein and DNA respectively.
A REGULATORY SYSTEM CONTROLLING INHIBITION IN THE SEXUAL CYCLE OFNEUROSPORA
Authors: Howe Jr. H. Branch , Prakash V.
Published: November 2014

A cross made by adding conidia to protoperithecia on a mycelium of opposite mating type inhibits a subsequent cross on the same mycelium, or on an adjacent mycelium connected either by hyphae or medium. The inhibitory activity reaches a steady rate of movement through the area of the second cross from the area of the first cross and brings about either total or partial inhibition of the second cross, depending upon certain controllable variables; translocation of the activity occurs primarily through the hyphae but to a lesser degree through the medium as well. Total inhibition is not a result of modification of the medium by the first cross, such as depletion of nutrients or change in pH. An uncrossed mycelium which received activity from a crossed mycelium becomes inhibited either irreversibly or, to a certain extent, reversibly, depending upon the degree of activity received; in either event, transmission of this passive activity may occur from this mycelium to an outgrowing mycelium on fresh medium. The experiments reported here were done primarily with N. tetrasperma, in which the inhibitory effect was first found, but the effect has also been observed in N. crassa.
GENETIC AND CYTOLOGICAL EFFECTS OF THREE DESYNAPTIC GENES IN THE TOMATO
Authors: Moens Peter B.
Published: November 2014

In the normal tomato the genetic distance between d and aw is 12, between aw-wv 16, and between wv-centromere 38. In plants homozygous for the desynaptic gene as1, the percentage recombinants among the offspring is near normal. In as4plants the distance d-aw is 31 and aw-wv 39, a 2.4-fold increase for both map segments. In asbthe distance d-aw is 18, the distance aw-wv is 36 and the distance wv centromere is 50.Cytology of the desynaptics indicates that initial pachytene pairing is normal, as judged from light and electron microscope observations. At later stages of pachytene, pairing is variable and at diakinesis there is a high frequency of univalents and a low frequency of chiasmata. The meiotic divisions are defective and fertility is low. Gametes from cells with high levels of crossing over may have a selective advantage in the desynaptic plants, so that as a result the frequency of recombinants is high among the progeny. However, in the case of as4and asb, it would seem more likely that the process of genetic exchange itself is interfered with.
INHERITANCE OF RADIATION-INDUCED SPINAL CURVATURES IN THE GUPPY LEBISTES RETICULATUS
Authors: Schröder Johannes Horst
Published: November 2014

Hereditary changes in the shape of the vertebral column in Lebistes reticulatus appeared after ancestral irradiation of immature germ cells with 500 or 1000 R of X-rays. Although the mutant to wild-type ratios in the F2 generation after outcrossing fitted a digenic and a trigenic segregation ratio, respectively, the quantitative characters in question are assumed to be caused by recessive mutations of polygenes which are highly mutable.
INHERITANCE OF PROTEIN CONTENT AND SEDIMENTATION VALUE IN DIALLEL CROSSES OF SPRING WHEAT (TRITICUM AESTIVUM)
Authors: Hsu C. S. , Sosulski F. W.
Published: November 2014

The inheritance of flour protein content and sedimentation value was investigated in diallel crosses among four hard red spring wheat varieties. Variances for the space-planted parental and F2populations were relatively high. Broad sense heritability values for each trait averaged 55% in the six crosses. Use of purified lines as parents in a 3-selection diallel did not alter the heritability of protein content but the estimates for sedimentation value were substantially improved.Phenotypic correlations in the F2populations indicated the two quality traits had no consistent relationship, positive or negative depending on the cross. The negative association of protein content with grain yield was significant in nearly all crosses.The diallel cross analysis showed that each quality factor was controlled primarily by intragenic allele systems. Sedimentation value showed partial dominance, with dominant genes contributing to high measurement. Over-dominance in slight magnitude was indicated for protein content, with both dominant and recessive genes contributing to the high expression of this character.
NUCLEAR SEX DIMORPHISM IN THE MONGOLIAN GERBIL
Authors: Garner James G. , Meskill Victor P. , Hanan Frank
Published: November 2014

Sectioned material from male and female gerbils, Meriones unguiculatus, was stained with the Biebrich scarlet-fast green FCF procedure for sex chromatin and the Feulgen technique for DNA. There was a significant sex difference among the nuclei of male and female cerebral cortex neurons, kidney cuboidal epithelium, intestinal columnar epithelium, liver parenchymal cells and skeletal muscle nuclei.
MATERNAL EFFECTS ON LITTER SIZE IN MICE
Authors: Eisen E. J.
Published: November 2014

An extensive set of data from a selection experiment for 12-day litter weight in mice was analyzed to determine whether standardizing litter size to a constant number at 5 days of age removed the negative environmental maternal effect (acting through adult body weight of the daughter) on litter size. The regression of daughters' litter size on dams' litter size was 0.070 ± 0.013 (d.f. = 851), which was partitioned into a relatively large direct additive genetic effect (0.067) and a negligible environmental maternal effect (0.003). Evidence is also presented that a positive genetic maternal effect influences litter size, which is probably mediated through adult body weight.
CYTOGENETIC STUDIES INARABIDOPSIS THALIANA
Authors: Sears Lotti M. S. , Lee-Chen Suzanne
Published: November 2014

The five primary trisomics and one telotrisomic of Arabidopsis have been established and identified with respect to known linkage groups. From diplotene preparations the chromosome complement was seen to comprise one long, three medium, and one short chromosome. All the trisomics except Fragilis were transmitted through the male (in frequencies up to 22%). There appears to be some selection against disomic eggs, only 21-30% recovery being observed from selfed trisomics. No tetrasomics were found.