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1.
Zusammenfassung Die beste N-Quelle für das Mycelwachstum ist Harnstoff, gefolgt von Alanin, Arginin, Asparagin, Prolin und Phenylalanin.Für die Primordienbildung ist bei N-Applikation im Nährboden kein eindeutiges Resultat zu erhalten. Die Zahl der Anlagen und ihre Anordnung am Mycel variiert sehr stark je nach dem Stamm, der N-Quelle und dem Zeitpunkt, zu dem die Mycelien Fruktifikationsbedingungen bekommen. Werden die Testsubstanzen jedoch in einem Tropfen Pufferlösung zugesetzt, nachdem die Mycelien den optimalen Durchmesser erreicht haben, so ist Asparagin besonders gut. Beim Stamm M7 kann Arginin ebenso gut verwertet werden, aber erst 1,5–2 Tage später. Bei 42×11 ist nur das Asparagin eine adäquate N-Quelle. Alle übrigen Substanzen sind eindeutig schlechter, vor allem Phenylalanin und Prolin.Der optimale Durchmesser ist eine stammspezifische Größe. Er wird weder von der N-Ernährung noch von der Wachstumsgeschwindigkeit, noch dem absoluten Alter des Mycels beeinflußt. Bei ihm erscheinen die Primordien früher als bei kleineren oder größeren Mycelien. Mit der Tropfenmethode ist bei ihm außerdem die Primordienzahl besonders hoch und reproduzierbar.
Effect of some N-compounds on growth of mycelium and formation of primordia in the basidiomycete Pleurotus spec. from Florida
Summary For mycelial growth, the best nitrogen source is urea followed by alanine, arginine, asparagine, proline and phenylalanine.For primordia formation no clear results can be obtained by addition of the nitrogen source in the medium. The number of fruiting body initials, as well as their arrangement on the mycelium varies to a large extent depending upon the particular strain, the N source and the time at which the mycelia have been given fruiting conditions. If, however, the test substances are added in a drop of buffer as soon as the mycelia have reached their optimal diameter, asparagine is most suitable. Strain M7 is able to use arginine to the same extent, although with a lag of 1.5 to 2 days. For 42×11 only asparagine is an adequate N source; all other substances tested are clearly less suitable especially phenylalanine and proline.The optimal diameter is a strain specific figure. It is not influenced by the nitrogen nutrition, the growth intensity or the absolute age of the mycelium. The primordia do develop earlier on mycelia with the optimal diameter than on smaller or larger ones. In addition, the number of primordia is very pronounced with the drop method and reproducible.
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2.
Summary We have mapped and sequenced the globin gene and seven surrounding Alu repeat sequences in the orangutan globin gene cluster and have compared these and other orangutan sequences to orthologously related human sequences. Noncoding flanking and intron sequences, synonymous sites of , , and globin coding regions, and Alu sequences in human and orangutan diverge by 3.2%, 2.7%, and 3.7%, respectively. These values compare to 3.6% from DNA hybridizations and 3.4% from the globin gene region. If as suggested by fossil evidence and molecular clock calculations, human and orangutan lineages diverged about 10–15 MYA, the rate of noncoding DNA evolution in the two species is 1.0–1.5×10–9 substitutions per site per year. We found no evidence for either the addition or deletion of Alu sequences from the globin gene cluster nor is there any evidence for recent concerted evolution among the Alu sequences examined. Both phylogenetic and phenetic distance analyses suggest that Alu sequences within the and globin gene clusters arose close to the time of simian and prosimian primate divergence (about 50–60 MYA). We conclude that Alu sequences have been evolving at the rate typical of noncoding DNA for the majority of primate history.Presented at the FEBS Symposium on Genome Organization and Evolution, held in Crete, Greece, September 1–5, 1986  相似文献   

3.
A comparison of different habitats, biogas plant, rumen fluid and sewage sludge, for cellulolytic organisms indicated sewage studge was the best source. Enrichment cultura gave a mixed culture which exhibited CMCase activity as well as extracellular Avicelase, xylanase, -glucosidase, -xylosidase activities and cell-bound -glucosidase, and -xylosidase production in a synthetic medium with eleven different cellulosic and lignocellulosic substrates. The activity of extracellular -glucosidase and -xylosidase production was significantly higher than endogenous activities. Hemicellulases were induced better than cellulases. The anzyme system was stable under aerobic conditions. Of the different lignocellulosic substrates, kallar grass was the best inducer of extracellular enzymes.
Résumé La comparaison de différents habitats: digesteur méthanique, fluide du rumen ou boue de station d'épuration, pour leur contenu en organismes cellulolytiques, indiquent que la boue de station d'épuration est la meilleure source. Une culture par enrichissement a produit une culture mixte qui a exhibé aussi bien une activité CMCase que des activitiés extracellulaires avicelasique, xylanasique, -glucosidasique et -xylosidasique et qu'une production de -glucosidase et de -xylosidase liées à la cellule, dans un milieu synthétique et pour onze substrats cellulosiques et lignocellulosiques différents. L'activité de la -glucosidase extracellulaire et la production de -xylosidase sont significativement plus élevées que les activitiés endogènes. Les hemicellulases sont mieux induites que les cellulases. Le système enzymatique est stable dans des conditions aérobies. Parmi les divers substrats lignocellulosiques, l'herbe Kallar est le meilleur inducteur d'enzymes extracellufaires.
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4.
Summary Paraganglion-like structures (PLS) containing chromaffin-positive cells have been reported to be present in the adult human heart. The present work was initiated in order to evaluate the densitity of these structures in the interatrial septum and to study the presence of immunoreactivity of their cells to NSE and PGP 9,5 antibodies, two neuroendocrine markers. Six hundred 6-m paraffin serial sections were obtained from the upper third of the interatrial septum from six adult human hearts. From 2 to 12 paraganglia were found in each case, and their principal cells stained positively with NSE and PGP 9,5 antibodies. Depending on how these PLS related to other cardiac structures, four different types were identified: Type I — True paraganglia (located adjacent to ganglia or nerve fibers); Type II — Free paraganglia (immersed in the interatrial adipose tissue, without evident connection to other structures); Type III — Intraganglionic paraganglia (located within the nervous ganglia); Type IV — Intramyocardic paraganglia (small nests of immunoreactive cells closely related to myocardiocyte bundles). These cardiac paraganglia, which probably belong to the visceral-autonomic group, may have a role in the regulation of the cardiac function and in the adaptive mechanisms of the heart. Its is also possible that they originate functioning and non-functioning tumours.Work supported by grants from FINEP and CNPq (Brazil)  相似文献   

5.
An electron microscope study of the spermatocytes I of Scaptericus borrelli was performed using serial sections and tridimensional reconstruction. The stages examined were: mid-pachytene, early diplotene and the so-called diffuse stage. At mid-pachytene the nucleolus (associated to an autosome) shows a glomerular array formed of supernumerary synaptonemal complexes (extra-complexes, ECs). At early diplotene the autosomes still show remnants of synaptonemal complexes (SC) and the sex chromosome is formed by two substances: one is homogeneous (chromatin-like) the other is granular and dense. A short number of ECs occur in the latter. — At the diffuse stage (lobulated in this paper) the SCs remnants and the ECs have disappeared and the granular material is assembled in a nuclear lobule. This lobule was found associated with one centriole. — A tridimensional model of a diplotene nucleus and models of diplotene bivalents are shown. — The capacity to form repetitive components of the synaptonemal complex type by spermatocytes of the super-Family Grylloidea is discussed.  相似文献   

6.
Summary Sporulation of S. cerevisiae MAT/MATa was accompanied by a novel pattern of protein synthesis as shown by the disappearance of some mitotic polypeptides and by the appearance of a new set of meiotic polypeptides. Inhibition of mitochondrial protein synthesis by erythromycin within the 1st h caused the disappearance of several meiotic polypeptides. These meiotic polypeptides were also sensitive to cycloheximide and were localized in the cytosol, demonstrating that they were not mitochondrial translational products. Since erythromycin affected neither protein synthesis nor sporulation in a mitochondrially inherited er y mutant, we conclude that mitochondrial protein synthesis is needed for the expression of some nuclear genes during sporulation.  相似文献   

7.
Summary The dorsal tegument of the mature cercaria of Notocotylus attenuatus is a syncytial, cytoplasmic layer, containing two types of secretory granule which are identifiable ultrastructurally. The type 1 secretory bodies are electron lucid, whereas most type 2 granules have a banded appearance. The ventral tegument contains granules which are secreted from the type 3 cells; the type 3 granules are membrane bound, electron dense, and consist of both an amorphous and a finely striated zone. The type 4 cells mainly contain cigar-shaped granules consisting of an amorphous core surrounded by concentric striations. The granules exhibit structural variability in shape and content. The type 4 cells undergo a cellular migration to the tegument during encystment. The structure of the posterior-lateral glands and mode of secretion of the granules are described. Possible functions of microtubules are discussed for each cell type. Details of some secretory processes involved in the formation of the hemispherical cyst wall are described. The layers of the cyst wall may be related to the granular contents of the various parenchymal cells of the cercaria. The tegument of the metacercaria originates primarily from the cytoplasm of the type 1, type 2, type 3 and type 4 cells.  相似文献   

8.
InEchinops the flowers are surrounded by several scales and initiated in an acropetal and spiral succession on a cone-like inflorescence axis (Figs. 1–6). The floral organs originate in the following sequence: petals—stamens—carpels—pappus. The petals arise from a meristematic rim and therefore are already interconnected when they arise as primordia. This sympetalous zone remains rather inconspicuous for a long period, but eventually, the elongated corolla tube is formed through intercalary growth in a ring zone. Thereby, the stamens are moved upwards and form ledges on the corolla tube (Fig. 34). In the inferior ovary the usual zones of the typical angiospermous gynoecium can be distinguished, namely a synascidiate, symplicate and hemisymplicate zone. The ovule is borne on carpellary tissue.
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9.
Zusammenfassung Mechanisierte Sprachübersetzung, Speichern von Information und Mustererkennung stellen drei Sonderfälle der allgemeinen Operationen Lernen, Ordnen und Erkennen dar. Die Automatisierung solcher Operationen bildet nicht nur ein an und für sich interessantes Problem, sondern eine dringliche Notwendigkeit, sollen die universellen Gro Brechenanlagen nicht an der Komplexität ihrer inneren Organisation (soft-ware) ersticken. Als vielleicht einfachstes dieser drei — im Grunde nie getrennt auftretenden — Vorgänge, wird das Problem der Wiedererkennung betrachtet, d.h. dasjenige der Abbildung eines kontinuierlichen Ensembles reeller, metrischer Objekte auf eine endliche, diskrete Struktur ohne Metrik, wie sie beispielsweise das Innere einer digitalen Rechenanlage darstellt. Der notwendige Übergang vom heute einzig üblichen Speicher zum eigentlichen Gedächtnis hängt unter anderem von der Lösung dieses Problems ab. Seine Untersuchung hebt die grundsätzliche Bedeutung der Umgebung einzelner Objekte — ihres Kontextes — hervor, welche Umgebung im diskreten Raum das notwendige Äquivalent zum Kontinuum darstellt. Dies führt zu einer neuen Betrachtung des Paradoxon von Brillouin, und zur notwendigen Benützung dynamischer Methoden bei der Verarbeitung von Information, anders gesagt bei ihrer Überführung aus der bildhaft-kontinuierlichen Form in die diskrete, und zurück. Womit zumindest eine mögliche Definition nicht-trivialer Informationsverarbeitung gegeben ist.  相似文献   

10.
Analysis of chromatin-associated fiber arrays   总被引:7,自引:2,他引:5  
The distribution of constitutive heterochromatin has been investigated in four chromosomal races of the grasshopper Caledia captiva (2n= 23 /24 ) by the C-banding technique. Each of the four races was found to have a distinctive banding pattern which is associated with the inter-racial differences in chromosomal rearrangements. — The Ancestral race has a telocentric chromosome complement with large procentric C-bands which are structurally double on six pairs of chromosomes. The centromeres are unstained. — The General Purpose race has a C-banding pattern very similar to that seen in other Acridine grasshoppers with the majority of its chromosomes showing a centromeric localisation of the bands. — The two southern races, which show a complex polymorphism for presumed pericentric inversions on all twelve chromosomes, also show an unusually high level of interstitial and terminal C-bands. The different locations and numbers of these bands allow unambiguous identification of all the chromosome pairs within the complement. — In two cases, there is good evidence to indicate that a C-band redistribution between acrocentric and metacentric chromosomes has occurred by pericentric inversion. Furthermore, C-band variation on the long arm of the metacentric X-chromosome indicates the presence of a large paracentric inversion. This double inversion system has involved over 95% of the X-chromosome. — The interstitial and terminal C-bands probably have not resulted from heterochromatin movement within the complement but, more likely, have arisen by saltatory duplication of pre-existing sequences on the chromosome. — A new nomenclature system for banded chromosomes is proposed which allows most kinds of chromosomal restructuring and rearrangement to be adequately enumerated.  相似文献   

11.
R. H. Post 《Human genetics》1971,13(4):253-284
Summary Genetic traits which are disadvantageous or deleterious in primitive cultures, of hunters and food gatherers, have very low frequencies in almost all cases. There are a few special exceptions, such as the sickle cell trait. Some deleterious traits under genetic control are rare in primitive populations but have fairly high frequencies in populations with long histories or prehistories of civilization, such as Chinese, Japanese or European populations. The Darwinist might suggest that these traits have less selective disadvantage, that is, lower rates of selective elimination, in civilized habitats; i.e. that the various changes in habitat accompanying civilization have caused the rigor of natural selection to relax, in part or perhaps completely.Several cases are discussed of traits under genetic control or genetic influence which demonstrate this phenomenal contrast, between low frequencies among primitive populations and high frequencies among civilized populations. Population data are presented for 4 such cases: colorblindness, myopia, abnormality of the nasal septum and abnormally small external opening of the tear duct.
Zusammenfassung Mit einigen bekannten Ausnahmen, z. B. Sichelzellanämie, kommen genetische Merkmale, die bei den Urvölkern von Jägern und Sammlern ungünstig oder sogar schädlich wirkten, mit niedriger Häufigkeit vor. Genetisch bedingte schädliche Merkmale, die selten unter Urvölkern gefunden werden, kommen jedoch häufiger vor bei Bevölkerungen, die eine lange Geschichte bzw. Vorgeschichte der Zivilisation besitzen, wie z. B. in China, Japan oder Europa. Ein Darwinist würde behaupten, daß bei zivilisierten Wohnorten solche Merkmale selektiv weniger nachteilig wirken, d. h., daß die selektive Ausscheidung langsamer vorgeht. Anders gesagt: der mit der Zivilisation verbundene Wechsel des Wohnortes bildet einen Grund für eine Milderung der Strenge der natürlichen Auslese.Es werden einige genetisch bestimmte oder genetisch beeinflußte Merkmale besprochen, die den Unterschied zwischen den Häufigkeiten (niedrig bei Urvölkern, hoch bei zivilisierten Völkern) aufzeigen,. Für 4 solcher Fälle: Farbensinnstörungen, Kurzsichtigkeit, Nasenscheidenwand-Deformitäten und anomale kleine Außenöffnungen der Tränenwege werden die Befunde aus den Bevölkerungen dargestellt.
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12.
The degree of synchrony in the course of the interphase periods G1, S and G2 and in the initiation of mitosis in the several nuclei of each cell of a polynucleate population induced by treatment with 0.1% caffeine, in root meristems of Allium cepa, through inhibition of cytokinesis in two successive cell divisions is analysed by means of labelling with 3H-thymidine.—The S period is initiated simultaneously in all the nuclei of each polynucleate cell, which supports the hypothesis of a factor present in the cytoplasm that is responsible for inducing DNA synthesis.—However, all the nuclei in a polynucleate cell do not pass from the S period to the G2 period simultaneously, those surrounded by the greatest amount of cytoplasm, generally the outer nuclei, being the first to complete the S period (early nuclei) and beginning the prophase before their fellow-nuclei in the same cell (late nuclei).—From the metaphase onwards, however, all the nuclei in a polynucleate cell continue to develop synchronously. The synchronizing mechanism has a twofold aspect: the shortening of the G2 period in the late nuclei and the lengthening of it in the early ones and, on the other hand, an arrest of prophase in the early nuclei until the late ones have caught up, which suggests the existence of an inhibiting factor produced by the late nuclei capable of acting upon the early ones through the cytoplasm.  相似文献   

13.
C. Lee  X. Li  E. W. Jabs  D. Court  C. C. Lin 《Chromosoma》1995,104(2):103-112
The cosmid clone, CX16-2D12, was previously localized to the centromeric region of the human X chromosome and shown to lack human X-specific satellite DNA. A 1.2 kb EcoRI fragment was subcloned from the CX16-2D12 cosmid and was named 2D12/E2. DNA sequencing revealed that this 1,205 bp fragment consisted of approximately five tandemly repeated DNA monomers of 220 bp. DNA sequence homology between the monomers of 2D12/E2 ranged from 72.8% to 78.6%. Interestingly, DNA sequence analysis of the 2D12/E2 clone displayed a change in monomer unit orientation between nucleotide positions 585–586 from a tail-to-head arrangement to a head-to-tail configuration. This may reflect the existence of at least one inversion within this repetitive DNA array in the centromeric region of the human X chromosome. The DNA consensus sequence derived from a compilation of these 220 bp monomers had approximately 62% DNA sequence similarity to the previously determined 8 satellite DNA consensus sequence. Comparison of the 2D12/E2 and 8 consensus sequences revealed a 20 bp DNA sequence that was well conserved in both DNA consensus sequences. Slot-blot analysis revealed that this repetitive DNA sequence comprises approximately 0.015% of the human genome, similar to that found with 8 satellite DNA. These observations suggest that this satellite DNA clone is derived from a subfamily of satellite DNA and is thus designated X satellite DNA. When genomic DNA from six unrelated males and two unrelated females was cut with SstI or HpaI and separated by pulsed-field gel electrophoresis, no restriction fragment length polymorphisms were observed for either X (2D12/E2) or 8 (50E4) probes. Fluorescence in situ hybridization localized the 2D12/E2 clone to the lateral sides of the primary constriction specifically on the human X chromosome.  相似文献   

14.
Node explants collected from flowering plants of Vanda spathulata, an endemic and exquisite orchid of Peninsular India and Sri Lanka, were cultured in Mitra medium with combinations of 4.4–88.8 m 6-benzyl adenine (BA) and 0.0–114.2 m indole-3-acetic acid (IAA). Combinations of 44.4 m BA with 17.1 or 28.5 m IAA and 66.6 mM BA with 28.5 or 40.0 m IAA induced maximum formation of 12.6 and 12.1 shoots / node, respectively, in a 6-month period. Subcultured nodal explants produced maximum of 6.1 shoots at combinations of 22.2–44.4 m 21 BA and 5.7–28.5 m IAA. Rooting of shoots occurred in medium containing 75 g l–1 banana pulp and 5.7 m IAA within 3–9 weeks. Plantlets of 2–5 cm length possessing two to five roots established easily in community pots at 80–90% rates without hardening. Community potted plants introduced into forest segments at Ponmudi and Palode in Southern Western Ghats of India established at a rate of 50–70%.  相似文献   

15.
Zusammenfassung Eine speziell für die Verwendung in strömenden Körperflüssigkeiten konstruierte Caissonelektrode ermöglichte an dem zum Abduktor des Scherenfingers ziehenden Paar motorischer Axone die oszillographische Analyse der bei Reflexvorgängen eintretenden peripheren Interferenz von erregenden und hemmenden Impulsen. Werden mit dem Fingerglied der festgeklemmten Schere entsprechende kurze Bewegungen vorgenommen, so treten myotatische Reflexe auf, und die Aktionen der erwähnten 2 motorischen Ganglienzellen entsprechen dabei formell sehr weitgehend jenem Schema Sherringtons, durch welches für das spinale Säugerpräparat die — dortselbst intrazentral erfolgende — Umschaltung solcher Reflexvorgänge auf die gemeinsame Endstrecke aufgehellt wurde: Wir registrierten einerseits autogene, auf der Seite des gedehnten Muskels selbst eintretende Effekte (nämlich eine Streuentladung erregender Impulse, welche von einer kürzer dauernden, inversen Hemmeraktivierung begleitet ist) und anderseits die durch Dehnung des Antagonisten auszulösende reziproke Reaktion, welche aus einer Streuentladung von Hemmerimpulsen samt schwächerer inverser Aktivierung des Erregerneurons besteht. Für die am häufigsten auftretende Form der reflektorischen Antwort — die Streuentladung — darf als charakteristisch gelten, daß die Impulsfrequenz der im betreffenden Versuchstypus dominierenden, also eigentlich myotatischen Reaktion beinahe übergangslos auf durchschnittlieh 70 Hz emporstieg, um nach einem oder zwei entsprechend kurzen Intervallen (von z. B. 17 msec) zunächst auf mäßige Werte wie etwa 10–15 Hz abzusinken und dann früher oder später zu erlöschen.  相似文献   

16.
Weed assemblages from late medieval cornfields have been studied for the first time in northern Switzerland. Eleven samples from at least two different grain stores were investigated. The samples were collected from the carbonised remains of six wooden houses built in the late 13th century A.D. and which burnt down in the middle of the 15th century. The weed floras found in the spelt (Triticum spelta) and oats (Avena sativa) indicate a high botanical diversity in the cornfields at harvest time. Although oats are normally a summer crop and spelt a winter crop, both summer and winter crop weeds (as well as many different present-day grassland taxa) were found in each type of grain. Most of the weeds found were perennial plants, which was interpreted as an indication of both extensive tillage of the arable land and application of the three-field rotation system (Dreifelderwirtschaft). The spectra of the two palaeophytocoenoses (assemblages of ancient plant remains) studied suggest that the phytosociological method may not be reliable for classification of the late medieval remains into summer and winter crop weed communities. These findings should provide a better understanding of the development of anthropogenic plant communities, and in particular, the development of crop weed communities.  相似文献   

17.
Summary Effects of cycloheximide (CHM) on preprophase bands (PPBs) of microtubules (MTs) and on prophase spindle MTs in root tip cells of onion (Allium cepa L.) were examined. When root tip cells were treated with 36 M CHM for 0.5–4 h, the population of cells with a PPB did not decrease markedly although the population of mitotic cells and that of prophase cells with a PPB gradually decreased to half of the control root tips. In prophase cells treated with 11 and 36 M CHM for 2 h, the width of the PPB was 1.4 times broader than that in the prophase PPB without CHM. Electron microscopic observation on the cross section of the PPB showed that the number of MTs and the distance between adjacent MTs in prophase PPBs treated with CHM were similar to those in the early developmental stage of PPBs without CHM. The bipolar spindle, that appeared in late prophase was not seen in prophase cells treated with 11 M or higher concentrations of CHM for 2 h. In order to examine differences of perinuclear MT arrangement between CHM treated and non-treated prophase cells, arrangement of perinuclear MTs was examined by confocal laser scanning microscopy. In control cells without CHM, MTs appeared on the nuclear surface with several branched or cross over type MT foci in the cytoplasm when broad PPB formation started. These MT foci were replaced by the aster type MT foci, from which several MTs radiated along the nuclear surface. The aster type MT foci gradually gathered to form a bipolar spindle. MTs connecting the spindle pole region and the PPB were seen in late prophase. In CHM-treated cells (11-360 M for 2 h), branched and cross over type MT foci were prominent, even in prophase cells with well condensed chromosomes. Neither linkages of MTs between the spindle pole region and the PPB nor aster type MT foci were seen. These observations showed that CHM prevents the bundling of MTs in the PPB and also inhibits the formation of aster type MT foci that is essential for bipolar spindle development.  相似文献   

18.
Dinitroaniline herbicides are antimicrotubule drugs that bind to tubulins and inhibit polymerization. As a result of repeated application of dinitroaniline herbicides, resistant biotypes of goosegrass (Eleusine indica) developed in previously susceptible wild-type populations. We have previously reported that -tubulin missense mutations correlate with dinitroaniline response phenotypes (Drp) (Plant Cell 10: 297–308, 1998). In order to ascertain associations of other tubulins with dinitroaniline resistance, four -tubulin cDNA classes (designated TUB1, TUB2, TUB3, and TUB4) were isolated from dinitroaniline-susceptible and -resistant biotypes. Sequence analysis of the four -tubulin cDNA classes identified no missense mutations. Identified nucleotide substitutions did not result in amino acid replacements. These results suggest that the molecular basis of dinitroaniline resistance in goosegrass differs from those of colchicine/dinitroaniline cross-resistant Chlamydomonas reinhardtii and benzimidazole-resistant fungi and yeast. Expression of the four -tubulins was highest in inflorescences. This is in contrast to -tubulin TUA1 that is expressed predominantly in roots. Collectively, these results imply that -tubulin genes are not associated with dinitroaniline resistance in goosegrass. Phylogenetic analysis of the four -tubulins, together with three -tubulins, suggests that the resistant biotype developed independently in multiple locations rather than spreading from one location.  相似文献   

19.
Ueda T  Naoi H  Arai R 《Genetica》2001,111(1-3):423-432
In bitterlings (Acheilognathinae) C- and Ag-banding karyotypes of 6 species-subspecies collected in China and South Korea were analyzed. The chromosomal constitution of 2n=46 (4SM+42ST) in Rhodeus atremius fangi was quite different from that of 2n=48 (8M+20SM+20ST) in other species-subspecies in Rhodeus. It was concluded from the analysis of banded chromosomes that the increase in number of ST during the karyotype change from 2n=48 to 2n=46 was achieved by a series of pericentric inversions from 24 M-SM to 24 ST, and the decrease in the diploid number was caused by an additional tandem fusion of 4 ST chromosomes, forming a new ST pair in the 2n=46 karyotype. The karyotype of Tanakia koreensis, T. signifer, and Acheilognathus macropterus is 2n=48 (8M+20SM+20ST), 2n=48 (8M+20SM+14–16ST+4–6 A), 2n=44 (14M+16SM+14ST), respectively. In R. ocellatus ocellatus, T. koreensis, T. signifer and A. macropterus, karyotype changes from 2n=48 to 2n=44 due to centric fusion and inversion have also been estimated. It was suggested that C-banding heterochromatin was greatly concerned with the karyotype evolution in bitterlings.  相似文献   

20.
Life-history characteristics of the double-ended pipefish, Syngnathoides biaculeatus (Bloch), were investigated to determine growth rate, degree of sexual dimorphism, size at maturity, and reproductive biology. Growth rates of wild juveniles and adults calculated from monthly progression of length-frequency modes ranged from 0.8mmd–1 (fish lengths 120–145mm standard length (SL)) in summer to 0.2mmd–1 in winter (185–200mm SL). Growth of laboratory-reared juveniles up to 63d old was greater, ranging from 0.8 to 2.3mmd-1. The von Bertalanffy growth constant K was estimated at 0.0076d- 1, or 2.8year–1. Morphological differentiation between the sexes based upon abdominal pattern was possible for fish larger than 120mm SL, with females possessing a zigzag pattern on the abdomen. The association between this pattern and sex was confirmed by histological gonad analysis. Males were significantly longer than females during four of seven seasons examined, and a 1:1 sex ratio was determined for all seasons except autumn when the ratio was female biased. The breeding season was marked by the appearance of pregnant males between October and April, and during courtship both species exhibited increased pigmentation. The minimum paternal size at maturity was 185mm, the maximum length recorded 260mm. Clutch size ranged between 60 and 200 eggs, with a mean of 153. Ovaries had a sequential pattern of egg development, resulting in egg batches that approximated the number of eggs carried by brooding males. Additionally, all eggs in a brood were at the same developmental stage. This suggests that one female provides all of the eggs for one male per breeding event in a monogamous mating system.  相似文献   

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