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1.
High level of divergence of male-reproductive-tract proteins, between Drosophila melanogaster and its sibling species, D. simulans 总被引:1,自引:0,他引:1
We compared male-reproductive-tract polypeptides of Drosophila melanogaster
and D. simulans by using two-dimensional gel electrophoresis. Approximately
64% of male-reproductive-tract polypeptides were identical between two
randomly chosen isofemale lines from these two species, compared with 83%
identity for third-instar imaginal wing-disc polypeptides. Qualitatively
similar differences were found between reproductive tracts and imaginal
discs when D. sechellia was compared with D. melanogaster and with D.
simulans. When genic polymorphism was taken into account, approximately 10%
of male- reproductive-tract polypeptides were apparently fixed for
different alleles between D. melanogaster and D. simulans; this proportion
is the same as that found for soluble enzymes by one-dimensional gel
electrophoresis. Strikingly, approximately 20% of male-reproductive- tract
polypeptides of either D. melanogaster or D. simulans had no detectable
homologue in the other species. We propose that proteins of the Drosophila
male reproductive tract may have diverged more extensively between species
than have other types of proteins and that much of this divergence may
involve large changes in levels of polypeptide expression.
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Steady flow of a viscous fluid through a network of tubes with applications to the human arterial system 总被引:1,自引:0,他引:1
The paper presents a finite-element model for the analysis of steady flow of a viscous fluid through a connected system of elastic tubes with the aim of simulating the conditions of blood flow through the human arterial system. The governing equations of the model are non-linear in character and are solved through an iterative computational procedure. This model is capable of incorporating the effects of stenosis on flow and pressure. Typical results are presented and discussed. Quantitative results have been obtained on blood flow through a model of the human arterial system corresponding to the sets of prescribed conditions at the terminations. Also computational results on the effect of stenosis in typical arteries of the system are presented. 相似文献
4.
Homozygous tyrosinase gene mutation in an American black with tyrosinase-negative (type IA) oculocutaneous albinism 总被引:5,自引:2,他引:3 下载免费PDF全文
R A Spritz K M Strunk C L Hsieh G S Sekhon U Francke 《American journal of human genetics》1991,48(2):318-324
We have identified a tyrosinase gene mutation in an American black with classic, tyrosinase-negative oculocutaneous albinism. This mutation results in an amino acid substitution (Cys----Arg) at codon 89 of the tyrosinase polypeptide. The proband is homozygous for the substitution, suggesting that this mutation may be frequently associated with tyrosinase-negative oculocutaneous albinism in blacks. 相似文献
5.
Summary Seven sites in two long-term fertility experiments progressing at PAU Farm Ludhiana were selected on the basis of fertilizer treatments they were receiving. Soil samples were obtained upto 225 cm depth at 15 cm interval and nitrate was estimated from them by phenol disulphonic acid method. In the first experiment, to each of the three sites, equal amount of N was applied. When phosphorus and potassium were added at the rate of 26.2 kg P/ha and 24.9 kg K/ha, there was little NO3
--N left in the profile for leaching, and where no P and K was added, lot of NO3
- was left in the profile unutilized. Graphs for P13K25 treatment were in between the two extremes. Perhaps by balanced fertilization roots become proportionately efficient absorbers and little amount of nutrients is left, which is not absorbed. In the second experiment, supply of NPK to all the three treatments was increased or decreased from the recommended dose in a proportionate manner. This resulted in a nitrate distribution pattern similar to that of control treatment where no N was applied and thus strengthened the case for balanced fertilization. 相似文献
6.
Zusammenfassung Extrakte 26 Tage alter Kulturen der (+)- und (–),Stämme vonArthroderma benhamiae (UAMH 2822, 2823) und ihre befruchtete Kreuzung (2822 x 2823) wurden mittels der Polyacrylamide-Gel Elektrophorese Methode auf ihre Proteine, Phosphatasen und Peroxidasen untersucht. Sowohl die (+)- wie auch die (–)-Stämme zeigten 8 Proteinbande, aber die mit Gymnothecien gekreuzten Kulturen zeigten nur 6 Bande. Wenn jedoch die Proteinprofile dieser zwei entgegengesetzten Paarungstypen und befruchteten Gymnothecien miteinander verglichen wurden, wurden Unterschiede in der Lage und Färbungsintensität einiger Bande beobachtet. Die säurehaltigen und alkalischen Phosphatasemuster der (+)- und (–)-Stämme waren ziemlich ähnlich, aber unterschieden sich von den Mustern gekreuzter, befruchteter Gymnothecienkulturen. Peroxidase Isozyme wurden in keinen der beiden Paarungstypen oder in den gekreuzten Gymnothecienkulturen entdeckt. 相似文献
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Pingfang Song Stephen S. Rekow Corey‐Ayne Singleton Harmanjatinder S. Sekhon Gregory A. Dissen Minerva Zhou Barbara Campling Jon Lindstrom Eliot R. Spindel 《Journal of neurochemistry》2013,126(4):451-461
Synthesis of acetylcholine (ACh) by non‐neuronal cells is now well established and plays diverse physiologic roles. In neurons, the Na+‐dependent, high affinity choline transporter (CHT1) is absolutely required for ACh synthesis. In contrast, some non‐neuronal cells synthesize ACh in the absence of CHT1 indicating a fundamental difference in ACh synthesis compared to neurons. The aim of this study was to identify choline transporters, other than CHT1, that play a role in non‐neuronal ACh synthesis. ACh synthesis was studied in lung and colon cancer cell lines focusing on the choline transporter‐like proteins, a five gene family choline‐transporter like protein (CTL)1–5. Supporting a role for CTLs in choline transport in lung cancer cells, choline transport was Na+‐independent and CTL1–5 were expressed in all cells examined. CTL1, 2, and 5 were expressed at highest levels and knockdown of CTL1, 2, and 5 decreased choline transport in H82 lung cancer cells. Knockdowns of CTL1, 2, 3, and 5 had no effect on ACh synthesis in H82 cells. In contrast, knockdown of CTL4 significantly decreased ACh secretion by both lung and colon cancer cells. Conversely, increasing expression of CTL4 increased ACh secretion. These results indicate that CTL4 mediates ACh synthesis in non‐neuronal cell lines and presents a mechanism to target non‐neuronal ACh synthesis without affecting neuronal ACh synthesis. 相似文献
10.
Patients with systemic autoimmune diseases usually produce high levels of antibodies to self-antigens (autoantigens). The
repertoire of common autoantigens is remarkably limited, yet no readily understandable shared thread links these apparently
diverse proteins. Using computer prediction algorithms, we have found that most nuclear systemic autoantigens are predicted
to contain long regions of extreme structural disorder. Such disordered regions would generally make poor B cell epitopes
and are predicted to be under-represented as potential T cell epitopes. Consideration of the potential role of protein disorder
may give novel insights into the possible role of molecular mimicry in the pathogenesis of autoimmunity. The recognition of
extreme autoantigen protein disorder has led us to an explicit model of epitope spreading that explains many of the paradoxical
aspects of autoimmunity – in particular, the difficulty in identifying autoantigen-specific helper T cells that might collaborate
with the B cells activated in systemic autoimmunity. The model also explains the experimentally observed breakdown of major
histocompatibility complex (MHC) class specificity in peptides associated with the MHC II proteins of activated autoimmune
B cells, and sheds light on the selection of particular T cell epitopes in autoimmunity. Finally, the model helps to rationalize
the relative rarity of clinically significant autoimmunity despite the prevalence of low specificity/low avidity autoantibodies
in normal individuals. 相似文献