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1.
R. Garza C. Cardona S. P. Singh 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1996,92(3-4):357-362
The bean-pod weevil (BPW), Apion godmani Wagner, often causes heavy losses in crops of common bean (Phaseolus vulgaris L.). Farmers need resistant bean cultivars to minimize losses, cut production costs, stabilize seed yield, and reduce pesticide use and consequent health hazards. To design effective breeding methods, breeders need new and better sources of resistance and increased knowledge of their modes of inheritance. We therefore: (1) compared sources of resistance to BPW, (2) studied the inheritance of resistance, and (3) determined whether the sources possess similar or different genes for BPW resistance. The following sources of resistance, originating from the Mexican highlands, were evaluated for 3 years at INIFAP-Santa Lucía de Prias, Texcoco, Mexico: Amarillo 153, Amarillo 169, Hidalgo 58, J 117, Pinto Texcoco, Pinto 168, and Puebla 36. All except Puebla 36 were crossed with the susceptible cultivar Jamapa. Amarillo 153 and Puebla 36 were crossed with another susceptible cultivar, Bayo Mex. The parents, F1 hybrids, and F2 populations were evaluated for BPW damage in 1992. Backcrosses of the F1 of Jamapa/Pinto 168 to the respective susceptible and resistant parents were also evaluated in 1992. All seven resistant accessions were crossed in all possible combinations, excluding reciprocals. The resulting 21 F1 hybrids and 21 F2 populations were evaluated for BPW damage in 1994. J 117 had the highest level of resistance to BPW. Pinto Texcoco and Puebla 36 had the highest mean damage score of all seven sources of resistance. The F1 hybrids between susceptible parents and resistant sources were generally intermediate. Two genes segregating independently controlled the BPW resistance in each accession. One gene, Agm, has no effect when present alone, whereas the other gene, Agr, alone conferred intermediate resistance. When both genes were present, resistance to BPW was higher. Based on mean BPW damage scores, all 21 F1 hybrids and their F2 populations, derived from crosses among seven resistant accessions, were resistant. However, data from individual plant damage scores in F2 populations of Amarillo 169/Pinto 168 and Pinto Texcoco/Pinto 168 suggested that at least one gene in each of the three accessions was non-allelic. Data also indicated that Amarillo 169 had a dominant gene that conferred high levels of BPW resistance, irrespective of the alleles at the other locus; and that Pinto Texcoco and Pinto 168 possessed two different genes for intermediate resistance. 相似文献
2.
Using the analysis of the interaction between EEG components [1], the authors studied the regularities of the formation of the EEG wave structure in 36 children aged 4 to 7 months, 2 to 3 years, and 4 to 5 years. The EEG of 4- to 7-month-old children had a relatively organized temporal structure, whose components were connected mainly with those of the slow-wave range. This structure is reproduced in most of the leads and is more stable in the anterior cortical areas than in the posterior ones. The waking 2- to 5-year-old children had two functional nuclei in the relation structure of the EEG components characterized by statistically significant enhancement in the probability of the consecutive appearance of waves of certain ranges. These nuclei include a slow-wave nucleus in the range of the 2–1-frequencies and an alpha-nucleus in the 1- and 2-ranges (2 and 1 2- to 3-year-old children) of the EEG frequencies. The relations between the components of the slow-wave nucleus begin to form in infants, prevail in 2- to 3-year-old children, and weaken by the age of 4 to 5 years. A trend is observed in 2- to 5-year-old children towards an increase in the average frequency of the waves that form the slow-wave nucleus. The temporal (strengthening interaction between the waves) and spatial organization of the interaction between the wave components of the alpha-nucleus is accelerated at the age of 4 to 5 years. The average frequency of the components forming this nucleus gradually increases with the children's age from 4 to 7 months to 4 to 5 years. Competitive relations exist between the two nuclei, characterized by a significant decrease in the probability of transitions between the components of different nuclei. The 2-component may play a special role of the connecting link between the nuclei at the age of 4 to 5 years, the interwave transition from the - to -frequencies and from the latter to the -range being effected by a leaplike rather than smooth frequency increase. The character of local and spatial rearrangements of the EEG temporal structure detected in this study reflects a gradual morphofunctional maturation of the brain as a system that maintains the specific features of self-regulation mechanisms and coordination of the intersystem interactions at various stages of a child's development. 相似文献
3.
W. J. Schmidt 《Zoomorphology》1967,58(3):273-289
Zusammenfassung Es wird die Schale eines Zwergeies vom Huhn beschrieben. Kalkschale und Schalenmembran sind — an der Größe des Eies gemessen —dicker als gewöhnlich, und dazu erwies sich der Aufbau der mucoidreichen Schalenmembran als ungemein dicht. Bei der Entwicklung des Zwergeies setzte zunächst normale Schalenbildung ein, welche die Eisosphäriten, die Kegel und den unteren Abschnitt der Säulen lieferte. Dann aber kam es, vermutlich durch Pberangebot von Kalk, zur massenhaften Bildung von Calcosphäriten, zur Entstehung der Konglomeratschicht. Weiter verlängern sich Einzelkristalle der Konglomeratschicht unter lateraler Wachstumsbeschränkung zu aufrecht stehenden, dicht aneinanderschließenden Stelen Von den Kegeln bis zur Schalenoberfläche treten in allen Schichten Hyalosphariten auf, die als Anzeichen gestörter Schalenentwicklung gelten dürfen. Die Schale des Zwergeies enthält in allen Schichten des Exosphäriten Protoporphyrin, das sich an seiner typischen Rotfluorescenz zu erkennen gibt; insbesondere häuft es sich in der Konglomeratschicht an, bald in den Kalk aufgenommen, bald in unverkalkte organische Substanz zwischen den Kristallen eingebettet. Die zahlreichen Höckerchen des Zwergeies entstehen teils durch lokale Anhäufung von Hyalosphariten, teils aber als Extrusionen.
Summary The shell of a dwarf-egg from the hen will be described. The calcitic shell and its membrane — in relation to the egg size — are thicker than normally; farther the structure of the shell membrane, reach on mucoid presents an exceeding density. In the development of the dwarf-egg first the normal shell production began, which supplied the eisospherites, the cones and the basal part of the columns. But then, probably effected by an abounded offer of calcite, the formation of numerous calcite spherites began, the conglomerate layer arised. Farther under lateral growth limitation monocrystals of the conglomerate layer lengthened to vertically orientated steles. In all layers of the exospheritic shell hyalospherites appear; they could be concerned as a symptom of disturbed shell formation. The shell of the dwarf-egg contains in all layers of the exospherite protoporphyrin granules, cognoscible by their typical red fluorescence. Especially the porphyrin is accumulated in the conglomerate layer, included in the calcite or embedded in the organic substance between the crystals. The numerous humps of the dwarf-egg arise partly by local aggregation of hyalospherites but partly as extrusions.相似文献
4.
-Crystallin is a common lens protein of most vertebrate eye lenses and the major protein component in lenses of fishes and in many mammalian species during embryonic and neonatal stages. To facilitate the structural characterization of -crystallin possessing extensive charge heterogeneity, a cDNA mixture was constructed from the poly(A)+ mRNA isolated from shark eye lenses, and amplification by polymerase chain reaction (PCR) was carried out to obtain cDNAs encoding multiple shark -crystallins. Sequencing analysis of multiple positive clones containing PCR-amplified inserts revealed the presence of a multiplicity of isoforms in the -crystallin class of this cartilaginous fish. It was of interest to find that two shark cDNA sequences coexist, one encoding -crystallin (M1) of high methionine content (15.5%) and the other encoding one (M2) of low methionine content (5.1%), each corresponding to the major teleostean and mammalian -crystallins, respectively. Comparison of protein sequences encoded by these two shark cDNAs with published sequences of -crystallins from mouse, bovine, human, frog, and carp lenses indicated that there is about 61–80% sequence homology between different species of the piscine class, whereas only 47–66% is found between mammals and shark. A phylogenetic tree constructed on the basis of sequence divergence among various -crystallin cDNAs revealed the close relatedness between shark M2-crystallin and mammalian -crystallins and that between shark M1 and teleostean -crystallins. The results pointed to the fact that ancestral precursors of -crystallins were present in the sharp lens long before the appearance of modern-day mammalian and teleostean -crystallins. 相似文献
5.
Gerhard Röbbelen 《Molecular & general genetics : MGG》1962,93(1):25-34
Zusammenfassung Nach Röntgenbestrahlung vonArabidopsis thaliana wurde in der X1-Generation auf Grund einer intraindividuellen Musteranalyse sowie entsprechender Kreuzungen eine gesicherte Erhöhung der Rate von plasmonisch bedingten Blattfarbveränderungen festgestellt. Bei der Mehrzahl dieser X1-Pflanzen waren die mutierten, zumeist weißen Gewebe sektorialchimärisch angeordnet; Schecken, wie sie durch eine zufallsgemäße Entmischung erblich verschiedener Plastiden entstehen, fanden sich nur in 8,3% aller Fälle. Verschiedene der induzierten Formen konnten durch einen cytologischen Nachweis von Plastiden-Mischzellen als Plastom-Mutanten identifiziert werden. Insgesamt stieg die Häufigkeit der sicher erwiesenen Fälle von Plasmonabänderungen im Mittel zweier Versuche von einer Spontanrate um max. 0,07 nach Samenbestrahlung auf 1,95 und nach einer Bestrahlung von Zygoten auf 0,95. Damit wurde erstmalig die Möglichkeit aufgezeigt, auchdie Mutationshäufigkeit extrachromosomaler Erbstrukturen durch eine Röntgenbestrahlung zu erhöhen.Mit 5 TextabbildungenHerrn Professor Dr. A.Scheibe zum 60. Geburtstag gewidmet. 相似文献
6.
Yasuyoshi Yamamoto Karin Backlin Hiroshi Nakagomi Eva Halapi Claes Juhlin Anders Bucht Rolf Kiessling 《Cancer immunology, immunotherapy : CII》1993,37(3):163-168
The cytotoxic activity and T cell receptor (TCR) V repertoire in tumor-infiltrating lymphocytes (TIL) of three primary adrenal cell carcinomas were analyzed. Fresh, non-cultured TIL from two of the three tumors showed low but significant lysis of the autologous tumor, and for one of the patients this activity was strongly enhanced upon culture in interleukin-2. An allogeneic adrenal cell carcinoma line and the K562 or Daudi targets included as controls were not killed. Phenotypic analysis of freshly isolated TIL demonstrated that the cells from the two patients that demonstrated cytolytic capacity mainly consisted of CD45RO+ T cells. In vitro cultured TIL lines from these patients demonstrated a high percentage of CD8+ cells expressing either the V6 gene or the V8 gene product, as measured with a panel of mAb specific for TCR V and V gene products. Analysis of the TCR V gene mRNA expression in freshly isolated non-cultured TIL, using a polymerase-chain-reaction-assisted cDNA-amplification assay, confirmed the strong expression of the genes coding for the TCR V6 or the V8. This assay also demonstrated a more restricted TCR V gene usage in the TIL as compared to peripheral blood lymphocytes from the same patient.This study was supported by the Swedish Cancer Society and by the Cancer Society in Stockholm 相似文献
7.
Summary Five subunits (-, -, -, - and -subunits) of the six -and -subunits) in the F1 portion (F1ATPase) of sweet potato (Ipomoea batatas) mitochondrial adenosine triphosphatase were isolated by an electrophoretic method. The - and -subunits were not distinguishable immunologically but showed completely different tryptic peptide maps, indicating that they were different molecular species. In vitro protein synthesis with isolated sweet potato root mitochondria produced only the -subunit when analyzed with anti-sweet potato F1ATPase antibody reacting with all the subunits except the -subunit. Sweet potato root poly(A)+RNA directed the synthesis of six polypeptides which were immunoprecipitated by the antibody: two of them immunologically related to the -subunit and the others to the - and -subunits. We conclude that the -subunit of the F1ATPase is synthesized only in the mitochondria and the -, - and -subunits are in the cytoplasm. 相似文献
8.
C. S. Spyropoulos 《The Journal of membrane biology》1979,47(3):195-238
Summary A previous method of measuring the swelling pressure (
g
) of the cytoplasmic gel of the giant axon ofLoligo vulgaris was refined. The estimates of
g
made with the improved method were consistent with those made with the earlier method. In these methods the activity of the solvent in the gel is measured by increasing the activity of the solvent in the internal phase of the gel by application of hydrostatic pressure to the gel directly. Comparable values for the activity of the solvent in the gel were obtained also by an alternate method, in which the deswelling of the gel is measured upon decreasing the activity of the solvent in the external phase by addition of a nonpenetrating high mol wt polymer (i.e., Ficoll).Additional support was obtained for the earlier suggestion that
g
contributes to the swelling and shrinkage pattern of the whole axon. In part, the new evidence involved two consecutivedirect measurements of intraxonal pressure. The first measurement was that of a mixed pressure composed of
g
and
m
(
m
being the effective osmotic pressure due to the intra-extraxonal gradient in the activity of mobile solutes). The subsequent measurement was that of
g
alone. The latter measurement was made feasible by destroying the axolemma, thereby eliminating the contribution of
m
. An estimate of
m
was obtained by subtracting
g
from the total pressure measured initially. The
m
determined by the above method was two orders of magnitude smaller than the theoretical osmotic pressure. This is consistent with the
m
determined previously, where osmotic intra-extraxonal filtration coefficients were compared to the hydrostatic. The mixed pressure experiments lend credence to the idea that the substantial contribution of
g
to the water relations of the whole axon is due to
g
being of the same order of magnitude as
m
.The degree of free swelling of axoplasmic gels was studied as a function of pH, salt concentration, and hydration radius of the anion of the salt used. The swelling increased with an increase in the reciprocal of the hydration radius, a decrease in salt concentration, and at pH below or above 4.5.The nature of the constraints to the free swelling of axoplasm in axons immersed in seawater was studied. With the seawater employed, these constraints appeared to be due more to the retractive forces of the sheath than to
m
. 相似文献
9.
Donor tissue and culture condition effects on mesophyll protoplasts of Medicago sativa 总被引:6,自引:0,他引:6
Mesophyll protoplasts were produced from clones of two cultivars of Medicago sativa, Rangelander and Regen S. Protoplasts from the Regen S clone generally gave rise to calli while those from the Rangelander clone would undergo direct embryogenesis. Effects of plant growth conditions, donor tissue pretreatment and protoplast culture conditions on mesophyll protoplast production and subsequent development patterns were investigated. The major factor determining whether or not mesophyll protoplasts would be produced from either of the clones was the pretreatment in water of shoots excised from the donor plants. Pretreatment in water containing growth regulators did not alter protoplast production or development in the Regen S clone. Pretreatment of the Rangelander clone shoots with abscisic acid or naphthaleneacetic acid was slightly beneficial to embryo production while pretreatment with benzylaminopurine was detrimental. Altered leaf morphology induced by growth condition changes did not affect mesophyll protoplast production or subsequent development patterns when shoots were pretreated in water. Culture of protoplasts in liquid droplets or solid agar medium increased low density protoplast survival and subsequent embryo production in the Rangelander clone. 相似文献
10.
In washed cells of cadmium-sensitive Staphylococcus aureus 17810S oxidizing glutamate, initial Cd2+++ influx via the Mn2+ porter down membrane potential () was fast due to involvement of energy generated by two proton pumps—the respiratory chain and the ATP synthetase complex working in the hydrolytic direction. Such an unusual energy drain for rapid initial Cd2+ influx is suggested to be due to a series of toxic events elicited by Cd2+ accumulation down generated via the redox proton pump: (i) strong inhibition of glutamate oxidation accompanied by a decrease of electrochemical proton gradient (
H
+) formation via the respiratory chain, (ii) automatic reversal of ATP synthetase from biosynthetic to hydrolytic mode, which was monitored by a decrease of
H
+-dependent ATP synthesis, (iii) acceleration of the initial Cd2+ influx down generated the reversed ATP synthetase, the alternative proton pump hydrolyzing endogenous ATP. The primary, cadmium-sensitive targets in strain 17810S seem to be dithiols located in the cytoplasmic glutamate oxidizing system, prior to the membrane-embedded NADH oxidation system. Inhibition by Cd2+ of
H
+-dependent ATP synthesis and of pH gradient (pH)-linked [14C]glutamate transport is a secondary effect due to cadmium-mediated inhibition of
H
+ generation at the cytoplasmic level. In washed cells of cadmium-resistant S. aureus 17810R oxidizing glutamate, Cd2+ accumulation was prevented due to activity of the plasmid-coded Cd2+ efflux system. Consequently,
H
+-producing and -requiring processes were not affected by Cd2+. 相似文献
11.
Summary A method for estimating CH-CH coupling constants from the shape and fine structure of NH-CH fingerprint-region cross peaks of COSY spectra is presented. Spectral simulations have been used to analyse the effect of variations in 3JNH-CH, 3JCH-CH, linewidths and digital resolution on the appearance of NH-CH COSY cross peaks. On the basis of these simulations a set of rules for broadly categorising experimental NH-CH cross peaks according to CH-CH coupling constants has been devised. The method has been applied to the analysis of NH-CH cross peaks of hen lysozyme. The results are compared to previous measurements of CH-CH coupling constants using E.COSY techniques. 相似文献
12.
Bernard Malaurie Jean-Claude Thouvenel Okito Pungu 《Plant Cell, Tissue and Organ Culture》1995,42(2):215-218
In vitro morphological development of meristem-tips, excised from microshoots, is reported for one clone Grosse Caille of D. cayenensis-D. rotundata complex and for one clone of D. praehensilis. The effects of size and location of meristem-tip on viability and morphological development after 3, 8 and 11 months in vitro culture were studied. The larger size of meristem-tip gave the best rooting and plantlet formation while the smaller size gave the best bud production. Axillary buds were more reactive than apical meristem-tips in callusing and rooting when small-sized meristems of the Grosse Caille clone were used; the use of larger meristem-tips did not induce more differences between apical and axillary buds. The production of plantlets was successful, after 11 months of culture, with a score of 82 and 39 % survivors, for Grosse Caille clone and D. praehensilis genotype, respectively.Abbreviations Ap
apical meristem-tips
- ApLS
large-sized apical meristem-tips
- Ax
axillary meristem-tips
- AxLS
large-sized axillary meristem-tips
- BA
6-benzyladenine
- cv
cultivar
- LS
large-sized meristem-tip
- NAA
naphthalenacetic acid
- SS
small-sized meristem-tip 相似文献
13.
Inka Brockhausen Folkert Reck William Kuhns Shaheer Khan Khushi L. Matta Ernst Meinjohanns Hans Paulsen Rajan N. Shah Michael A. Baker Harry Schachter 《Glycoconjugate journal》1995,12(3):371-379
UDP-GlcNAc:GlcNAc 1-2Man1-6R (GlcNAc to Man) 1,6-N-acetylglucosaminyltransferase V (GlcNAc-T V) adds a GlcNAc1-6 branch to bi- and triantennaryN-glycans. An increase in this activity has been associated with cellular transformation, metastasis and differentiation. We have used synthetic substrate analogues to study the substrate specificity and inhibition of the partially purified enzyme from hamster kidney and of extracts from hen oviduct membranes and acute myeloid leukaemia leukocytes. All compounds with the minimum structure GlcNAc1-2Man1-6Glc/Man-R were good substrates for GlcNAc-T V. The presence of structural elements other than the minimum trisaccharide structure affected GlcNAc-T V activity without being an absolute requirement for activity. Substrates with a biantennary structure were preferred over linear fragments of biantennary structures. Kinetic analysis showed that the 3-hydroxyl of the Man1-3 residue and the 4-hydroxyl of the Man- residue of the Man1-6(Man1-3)Man-RN-glycan core are not essential for catalysis but influence substrate binding. GlcNAc1-2(4,6-di-O-methyl-)Man1-6Glc-pnp was found to be an inhibitor of GlcNAc-T V from hamster kidney, hen oviduct microsomes and acute and chronic myeloid leukaemia leukocytes.Abbreviations all
allyl
- AML
acute myeloid leukaemia
- BSA
bovine serum albumin
- CML
chronic myelogenous leukaemia
- Gal
G,d-galactose
- Glc
d-glucose
- GlcNAc
Gn,N-acetyl-d-glucosamine
- HPLC
high performance liquid chromatography
- Man
M,d-mannose
- mco
8-methoxycarbonyl-octyl, (CH2)8COOCH3
- Me
methyl
- MES
2-(N-morpholino)ethanesulfonate
- oct
octyl
- pnp
p-nitrophenyl
- T
transferase 相似文献
14.
Alicia Mimbrera Luis Rivas Faustino Mollinedo Emilio Muñoz Vicente Larraga 《Molecular and cellular biochemistry》1983,56(1):73-80
Summary The combined use of proteolytic digestion and lactoperoxidase catalyzed labelling with [125I] applied to membrane-bound or soluble pure F1-ATPase from Micrococcus lysodeikticus has allowed us to establish the topography of its , , and subunits within the protein molecule and with respect to the plane of the membrane.The subunit is most externally located to the membrane bilayer looking towards the cytoplasmic face, a position consistent with its proposed catalytic role. The and subunits lie in an intermediate layer between the subunits and the membrane, in which the subunit occupies a central position within the F1-ATPase molecule in contact with the subunit. The subunit appears to be tightly bound to the F0 component of the ATPase complex, probably buried in the membrane bilayer. A molecular arrangement of M. lysodeikticus ATPase is proposed that, taking into account the subunit stoichiometry 3 3 2 2 (MW 420 000), accommodates the role assigned to each subunit and most, if not all, the known properties of this bacterial energy-transducing protein. 相似文献
15.
The activity of -carboline-2-N-methyltransferase results in the formation of neurotoxic N-methylated -carbolinium compounds. We have hypothesized that these N-methylated -carbolinium cations may contribute to the development of idiopathic Parkinson's disease. This report describes experiments undertaken to optimize assay conditions for bovine brain -carboline-2-N-methyltransferase activity. The activity of -carboline-2-N-methyltransferase is primarily localized in the cytosol, has a pH optimum of 8.5–9, and obeys Michaelis-Menten kinetics with respect to its substrates, 9-methylnorharman (9-MeNH) and S-adenosyl-L-methionine (SAM). Kinetic constants, KM and Vmax, with respect to 9-MeNH, are 75 M and 48 pmol/h/mg protein, respectively. The KM for SAM is 81 M and the Vmax is 53 pmol/h/mg protein. In addition, enzyme activity is inhibited by S-adenosyl-L-homocysteine (SAH) or zinc, and is increased 2-fold in the presence of iron or manganese. Enzyme characterization is a prerequisite to the purification of this N-methyltransferase from bovine brain as well as comparison of its activity in human brain from control and Parkinson's disease individuals. 相似文献
16.
Crude extracts or supernatants of broken cells of Clostridium formicoaceticum reduce unbranched, branched, saturated and unsaturated carboxylates at the expense of carbon monoxide to the corresponding alcohols. The presence of viologens with redox potentials varying from E
0=-295 to-650 mV decreased the rate of propionate reduction. The more the propionate reduction was diminished the more formate was formed from carbon monoxide. The lowest propionate reduction and highest formate formation was observed with methylviologen. The carbon-carbon double bond of E-2-methyl-butenoate was only hydrogenated when a viologen was present. Formate as electron donor led only in the presence of viologens to the formation of propanol from propionate. The reduction of propionate at the expense of a reduced viologen can be followed in cuvettes. With respect to propionate Michaelis Menten behavior was observed. Experiments are described which lead to the assumption that the carboxylates are reduced in a non-activated form. That would be new type of biological reduction.Non-standard abbreviations glc
Gas liquid chromatography
- HPLC
high performance liquid chromatography
- RP
reverse phase; Mediators (the figures in parenthesis of the mediators are redox potentials E
0 in mV)
- CAV2+
carbamoylmethylviologen, 1,1-carbamoyl-4,4-dipyridinium dication (E
0=-296 mV)
- BV2+
benzylviologen, 1,1-dibenzyl-4,4-dipyridinium dication (E
0=-360 mV)
- MV
methylviologen, 1,1-dimethyl-4,4-dipyridinium-dication (E
0=-444 mV)
- DMDQ2+
dimethyldiquat, 4,4-dimethyl-2,2-dipyridino-1,1-ethylendication (E
0=-514 mV)
- TMV2+
tetramethylviologen, 1,1,4,4-tetramethyl-4,4-dipyridinium dication (E
0=-550 mV)
- PDQ2+
propyldiquat, 2,2-dipyridino-1,1-propenyl dication (E
0=-550 mV)
- DMPDQ2+
dimethylpropyldiquat, 4,4-dimethyl-2,2-dipyridino-1,1-propenyl dication (E
0=-656 mV)
- PN
productivity number=mmol product (obtained by the uptake of one pair of electrons) x (biocatalyst (dry weight) kg)-1×h-1 相似文献
17.
Summary Southern blotting and DNA sequencing after polymerase chain reaction (PCR) amplification provide evidence for the frequent occurrence (in 7 out of 24 chromosomes) of a short conversion GA in the 3 end of the human fetal A globin gene. This short conversion is characterized by the presence, 3 nucleotides downstream from the termination codon of the A gene, of the TCAC sequence that is normally present at the equivalent position at the 3 end of the G gene; it is therefore identical to a conversion already described. Interestingly, we have found that this conversion is associated with the presence of theHindIII polymorphic restriction site in the A IVS2, occuppying an equivalent position in both the G and A genes. Our observations strengthen the hypothesis that the presence of the HindIII polymorphic restriction site in A IVS2 and the presence of the sequence TCAC at the 3 end of the A gene might be the result of a single conversion event. 相似文献
18.
E. Buchner 《Biological cybernetics》1976,24(2):85-101
In the theoretical part of the present work the input-output relation for a multi-input system is developed into a functional power series. This is formally equivalent to a decomposition of the system into a sum of all possible combinations of 1-, 2-, 3-... input subsystems. The average response of the system to a uniformly moving patern is known to be a Fourier series with respect to spatial frequency. The coefficients of the series are linear combinations of the weights by which different subsystems contribute to the total reaction. If a system can be shown to have essential nonlinearities of no higher than second order it is possible to calculate, from a Fourier analysis of the average movement response, the weight by which the nonlinear interaction between any two input elements contributes to the total reaction. This interaction is termed elementary movement detector. By the analysis presented here the arrangement of the elementary movement detectors may be determined for a two-dimensional array of input elements and the strength of their contributions to the total movement reaction may be calculated. Special experimental methods have been developed which allow one to apply this analysis to the visual system of the fruitfly Drosophila. The preliminary data presented show that the direction sensitive optomotor response of Drosophila can be attributed predominantly to the contributions from two elementary movement detectors which interconnect neighbouring visual elements. The detectors are oriented in the hexagonal array of the compound eye at +30° and at-30° with respect to the horizontal line of symmetry. A weak contribution from a detector between neighbouring elements along the horizontal line of symmetry is suggested by the present data. In the course of the analysis the contrast transfer properties of the compound eye are characterized. 相似文献
19.
A yeast-mycelium (Y-M) transition in Candida albicans was induced by exogenous yeast extract, adenosine, adenosine 5-monophosphate (AMP), adenosine 5-diphosphate (ADP), adenosine 35 cyclic monophosphate (cAMP) and its analogue N6, O2-dibutyryl adenosine 35-cyclic monophosphate (dbcAMP) in defined liquid medium at 25°C. Adenosine 5-triphosphate (ATP) was found to delay germ tube formation in yeast cells, whereas the cAMP phosphodiesterase inhibitors, theophylline and caffeine, induced a Y-M transition. Intracellular and extracellular cyclic AMP levels increased during the yeast-mycelium transition and maximum levels of intracellular cyclic AMP coincided with maximum germ tube formation. Of the many inducers and inhibitors of germ tube and mycelium formation in C. albicans tested, including incubation at 37°C or in the presence of 1.5mM CaCl2, the calmodulin inhibitor calmidazolium (R24571) added together with CaCl2 induced the highest intra- and extracellular cyclic AMP levels. These results confirm the involvement of cyclic AMP in the yeast-mycelium transition of C. albicans. 相似文献
20.
Carla Marchetti Carolina Amico Daniela Podestà Mauro Robello 《European biophysics journal : EBJ》1994,23(1):51-58
We have studied the mechanism of Ca current inactivation in the -cell line HIT-T15 by conventional and perforated patch recording techniques, using two pulse voltage protocols and a combination of current and tail current measurements. In 5 mM Ca, from a holding potential of - 80 mV, the maximum current showed a complex time course of inactivation: a relatively fast, double exponential inactivation (h1 12 ms and h2 60 ms) and a very slowly inactivating component ( > 1 s). The faster component (h1) was due to the voltage-dependent inactivation of a low-threshold-activated (LVA), T-type current, which deactivates more slowly ( 3–5 ms) than the other components ( 0.2–0.3 ms). The intermediate component (h2) was due to the Ca-dependent inactivation of a portion of the high-threshold-activated (HVA) current. A saturating dose of the dihydropyridine (DHP) nifedipine (10 M) did not affect the LVA current, but inhibited by 68 ± 5% the transient, Ca-sensitive portion of the HVA current and by 33 ± 12% the long lasting component. We suggest that three components of the calcium current can be resolved in HIT cells and the main target of DHPs is a HVA current, which inactivates faster than the DHP-resistant HVA component and does so primarily through calcium influx.
Correspondence to: C. Marchetti 相似文献