摘要:

The chromosomes of theAvenaspecies were studied and their karyotypes established. The karyotype of the diploid species (excludingA. longiglumis) is designated as A.Longiglumishas a different karyotype with at least three chromosomes that have major changes. This karyotype is a modified A, designated as A′. The designation of the tetraploid karyotype is AB, including the basic set of chromosomes A and a second completely different set B. In the hexaploid species the basic set A is present but the B set is not; therefore the proposed designation is ACD. These results indicate an alloploid origin for the polyploid species.

ISSN:0008-4026    

DOI:10.1139/b59-024

出版商:NRC Research Press    

年代:1959

数据来源: NRC

摘要:

Physiological studies of six isolates ofPhialophora fastigiataand two isolates ofP. richardsiaefrom pulp mills have been made to determine conditions for growth. Isolates ofP. fastigiatagrew from at about 3 °C to 30–35 °C, with optimum conditions at 20 to 25 °C and pH 4 to 9. The temperatures forP. richardsiaewere somewhat higher. No vitamins were required byP. fastigiatain a basal glucose mineral medium with ammonium tartrate. Ability to metabolize 11 carbohydrates as monosaccharides and oligosaccharides, but notD-arabinose, has been demonstrated. Likewise 16 sources of nitrogen as ammonia, nitrate, and various amino acids, but not cysteine, were utilized unequally. The differences between isolates ofP. fastigiatafrom the same slime were as great as between isolates from different mills.

ISSN:0008-4026    

DOI:10.1139/b59-025

出版商:NRC Research Press    

年代:1959

数据来源: NRC

摘要:

Distinguished from the rest of the genera of the Scilloideae,Dipcadiis characterized by tuberous scapigerous herbs with racemed flowers, cylindric perianth of six erect segments, the outer recurved from about the middle and the inner at the tips only, included stamens and a short capsule which is broad, tridymous, loculicidal, and many-seeded. The genus is insufficiently known both cytologically and embryologically. The present paper gives an account of micro- and mega-sporogenesis in a plant ofD. serotinum. This taxon, with a diploid chromosome number of eight and with all chromosomes having satellites and all apparently taking part in nucleolar organization, has other features of interest such as meiotic irregularities, abnormal megaspore tetrads, and polyspory. These have been recorded here and explanations are given as far as possible.

ISSN:0008-4026    

DOI:10.1139/b59-026

出版商:NRC Research Press    

年代:1959

数据来源: NRC

摘要:

Aspergillus nidulanswas grown on glucose, fructose, sucrose, or maltose in a high-sugar medium favorable for fat formation. Glucose was more readily metabolized than the other sugars, giving a heavy felt with the highest fat content in a shorter time. Sucrose was inverted before absorption and was more conducive to growth than to fat formation. Maltose was probably absorbed after hydrolysis. It gave a heavy felt and a high fat yield but after a longer period of incubation than with glucose. Maltose metabolism was marked by lower nitrogen utilization. Hence, the maltose-fed mycelial felts had the highest carbohydrate content and the lowest protein content.Growth proceeded as long as there was available sugar in the culture medium. Extracellular nitrogenous compounds appeared in the culture media before the complete exhaustion of the sugar in some cases, providing evidence that this process is not purely autolytic in nature. The early growth phase on the different sugars was characterized by low-fat, high-protein mycelial felts. Active fat formation was found to start after the drop of the nitrogen content of the medium to a very low level. The inverse relationship between fat and protein contents in the mycelium was traced during growth on glucose, sucrose, or maltose at different stages of growth. On fructose, except for the early growth period, fat and protein syntheses proceeded proportionally.

ISSN:0008-4026    

DOI:10.1139/b59-027

出版商:NRC Research Press    

年代:1959

数据来源: NRC

摘要:

Lines of a variety of common wheat, S-615, monosomic for chromosomes III and XVI of homoeologous group 3 had culms less solid in the top internode than normal S-615. Monosomics of homoeologous group 5, namely, V, IX, and XVIII, were less solid in the bottom four internodes than S-615. These five chromosomes carry genes for solid stem in this variety. Monosomics XIX, XX, and XXI, the D-genome chromosomes of homoeologous groups 6, 2, and 7 respectively, were more solid than the normal check in both top and lower internodes, indicating that the missing chromosomes carry genes for hollow stem. Chromosome XIII, a homoeologue of XX, which in Chinese Spring has a gene for hollow stem, does not affect the amount of pith in the culm of S-615.The concept of the culm phenotype in a given environment resulting from an interaction of genes promoting pith development and those opposing it makes it possible to reconcile results of genetic experiments on solid stem in wheat that previously appeared contradictory.

ISSN:0008-4026    

DOI:10.1139/b59-028

出版商:NRC Research Press    

年代:1959

数据来源: NRC

摘要:

Most monosomics of the solid-stemmed variety of common wheat, S-61S, were shorter than normal. Many had thinner culms, but monosomics XIII and XVI had thicker culms. Although the effect of loss of homoeologous chromosomes on culm dimensions was generally similar in S-615 monosomics and Chinese Spring nullisomics, the most extreme member of each group was not always the same in the two varieties. The differences between solid stem in monosomics and normal lines of S-615 were due to loss of the chromosome affecting pith production and not to secondary effects caused by changes in culm dimensions. Nevertheless, within lines of genetically similar plants there was a small but consistent association between short culm and solidness, between thin culm at the tops of internodes I, III, and IV and hollowness, and between thin culm in the center and lower parts of internode I and solidness. This has a bearing on interpretation of data in monosomic analysis of solid stem.

ISSN:0008-4026    

DOI:10.1139/b59-029

出版商:NRC Research Press    

年代:1959

数据来源: NRC

摘要:

When aqueous extracts of hull and caryopsis ofAvena fatuaare chromatographed, two inhibitory regions can be detected. These two inhibitors appear to be present in the hull and caryopsis in approximately equal amounts per unit weight of tissue. Evidence has been brought forward to show that the inhibitory effect of the hull in intact dormant seeds cannot be ascribed solely to the inhibitors present in the hull, nor does interference with gaseous exchange by this tissue account for its effect. Experiments have shown that isolated caryopses from dormant seeds germinate only when in contact with liquid water. Evidence from several experiments indicates that the hull may prevent leaching of inhibitors from the caryopsis which then allows of germination. It has been shown that inhibitors very readily diffuse out of the caryopsis on moist filter paper and that this process is retarded by the hull. Treatment with high oxygen concentrations, which promotes germination of very dormant seeds, appears to result in a reduction of inhibitor level before visible germination. In the induction of secondary dormancy under anaerobic conditions there is a marked increase in the total inhibitor level of the caryopses.

ISSN:0008-4026    

DOI:10.1139/b59-030

出版商:NRC Research Press    

年代:1959

数据来源: NRC

摘要:

After a 12-hour treatment in 10−5 Msolution of 2,4,6-tri(ethyleneimino)-1,3,5-triazine (TEM), up to 29% ofViciaand 31% ofAlliumroot cells in anaphase had bridges or fragments. The most abundant metaphase aberrations were chromosome breaks and chromatid interchanges. Aberrations were more numerous after 6-hour treatment with 2 × 10−5 Mthan after 12-hour treatment with 10−5 Msolution. The peak aberration frequencies were reached at 36 hours after 2 × 10−5 Mtreatments and slightly earlier with weaker solutions. Many chromosomes had incomplete breaks. Sister reunions of chromatids occurred with equal frequency in centric and acentric fragments. Sister reunion was 1.5 times as frequent as chromatid exchange. Along the length of the satellite chromosome, breaks occurred at random except for a slight favoring of the heterochromatic region. Per unit of length the short chromosomes were about 3 times as susceptible to breakage and exchange as satellite chromosomes. TEM introduced through cut stems had no discernible effects onTradescantiamicrospore chromosomes even after 3 to 5 days of treatment.

ISSN:0008-4026    

DOI:10.1139/b59-031

出版商:NRC Research Press    

年代:1959

数据来源: NRC

摘要:

Cytological observations are contained in this report on four dioecious species ofAmaranthns, two of which were formerly included in the genusAcnida. The species studied areA. arenicola, A. palmeri, A. tamariscinus, andA. tuberculatus. Three of these species have a diploid chromosome number of 32, whereasA. palmerihas a somatic chromosome number of 34. A single spontaneous triploid (2n = 48) female plant was found in collections ofA. tamariscinusand a tetraploid (2n = 64) male plant in collections ofA. tuberculatus. A fifth species,A. australis, has previously been reported as having 32 somatic chromosomes. The chromosome numbers for half the dioecious species ofAmaranthushave now been determined. Detailed observations on the dividing chromosomes of these species in mitosis, in meiosis, and in the first division of the nucleus in the pollen grain have been made and have failed to distinguish heteromorphic chromosomes which might be associated with sex determination. The small size of the chromosomes has made detailed morphological studies impractical and there is no marked difference in absolute size of the chromosomes between species. Since haploid numbers of 16 and 17 are found in both monoecious and dioecious species, it would seem that the aneuploid condition inAmaranthusarose early and hybridization within the genus has resulted in promoting the genie condition which has been necessary for the expression of the dioecious condition.

ISSN:0008-4026    

DOI:10.1139/b59-032

出版商:NRC Research Press    

年代:1959

数据来源: NRC

摘要:

A comparative study of specimens in several herbaria has revealed that the species ofLeptothyriumandKabatiaalready reported onLonicerafall naturally into several well-marked varieties, each of which is confined to one or a few hosts. Three new combinations,Leptothyrium periclymenivar.xylostei, Kabatia loniceraevar.americana, andK. loniceraevar.latemarensis, are made and two new varieties,K. loniceraevar.involucrataeandK. mirabilisvar.oblongifoliae, are described.Leptothyrium periclymeniattacks a limited number of hosts, which, however, occur in both subgenera ofLonicerawhereas theKabatiaspecies parasitize hosts belonging to a section of one subgenus.

ISSN:0008-4026    

DOI:10.1139/b59-033

出版商:NRC Research Press    

年代:1959

数据来源: NRC