A guinea-pig hereditary cataract contains a splice-site deletion in a crystallin gene

A congenital cataract present in guinea pigs provided a unique opportunity to study a hereditary lens diseases at the molecular level. ζ-crystallin, one of the most abundant guinea pig lens proteins, was found to be altered in the lens of cataractous animals. Several ζ-crystallin cDNA clones were isolated from a cataractous lens library and found to contain a 102-bp deletion towards the 3′ end of the coding region. The deletion does not interfere with the reading frame but results in a protein 34 amino acids shorter. Sequence analysis of a normal genomic ζ-crystallin clone revealed that the missing 102-bp fragment corresponds to an entire exon (exon 7). PCR analysis of the genomic DNA isolated from cataractous animals showed that exon 7, though missing from the mRNA, is intact in the cataractous genome. Further sequence analysis of the α-crystallin gene disclosed a dinucleotide delection of the universal AG at the acceptor splice-site of intron 6 of the mutant gene. The presence of this mutation results in the skipping of exon 7 during the mRNA processing which in turn results in the altered ζ-crystallin protein. This if the first time a genomic mutation in an enzyme/crytallin gene has been directly linked to a congenital cataract.     

血清胃泌素变化与急性胃粘膜病变关系的研究

对大白鼠血清中胃泌素水平的变化与急性胃粘膜病变的关系进行了初步的研究,结果表明以消炎痛为诱因引起的急性胃粘膜病变大白鼠血清胃泌素水平明显增高。而维酶素可以抑制因消炎痛引起的急性胃粘膜病变时血清胃泌素的释放,对胃粘膜具有保护作用。     

六种选矿药剂对藻类的毒性比较

本文评价了六种选矿药剂对藻类的毒性效应,它们对斜生栅藻的毒性大小排列顺序是:二号油>Fu>0145>Yx>MPA>S-808,96h-EC_(50)值分别为41.2,50.1,82.0,177.8,198.2和900ppm。六种选矿药剂对藻类毒性最大的是二号油,毒性最小的是S-808。对藻类细胞形态的观察结果表明,0145对藻类的细胞形态有轻度的致畸效应,在其它五种药剂的培养物中,均未发现畸变细胞。在室温下存放10d后MPA,0145和二号油,毒性明显下降,其下降速率的顺序是:MPA>0145>二号油。藻类对S-808具有净化脱色作用,100ppm浓度的S-808溶液经藻类作用32d后,其色度可减少48％,作用62d和93d,色度分别降低54％和58％。0145抑制藻类的光合放氧,经50,100和200ppm浓度的0145处理4h后,与对照相比,藻类的光合放氧速率分别下降15、34和36％。     

人α1/158Ⅴ型(α1c型)干扰素基因在大肠杆菌中的表达及其产物的初步纯化

采用DNA聚合酶链反应(PCR)技术,将本实验室从中国人胎肝细胞染色体DNA中发现和分离的IFN-α1/158V基因的原始克隆,改造成适于进行非融合蛋白原核表达的结构形式,并在大肠杆菌中获得高效表达。测得重组IFN-α1/158V的抗病毒活性为1.9×10~7单位/升菌液。随后又采用以单克隆抗体亲和层析为主的纯化流程对表达产物进行初步纯化,获得了在SDS-聚丙烯酰胺凝胶电泳上呈现单一条带的纯化产物。     

Mechanisms of embryonic drift in the amphidromous goby,Rhinogobius brunneus

Synopsis We tested the reactions of free embryos of the amphidromous goby, Rhinogobius brunneus, to light under both artificial and ambient conditions along streams in which their downstream migration occurs. The embryos showed a positive phototaxis to 500 1ux light but a negative response to light of more than 5000 lux. They were able to swim at 1.54 cm sec^–1 t in still water and showed positive rheotaxis, but their swimming ability was not sufficient to allow active movement in rapids. Ambient natural light conditions varied among locations in relation to local topographical features. The variation in the diel periodicity of their migration could be explained by the interaction between behavioral reactions of embryos and environmental factors along river courses.     

Sperm-oocyte membrane fusion in the human during monospermic fertilization

Sperm-oocyte membrane fusion has been observed during monospermic fertilization of a human oocyte in vitro. Women were stimulated with both clomiphene citrate and human menopausal gonadotropin and were given human chorionic gonadotropin before a LH-surge. Twelve oocytes, collected at laparoscopy from six women who became pregnant by IVF, were allowed to mature for 7–14 hours in vitro and inseminated with preincubated sperm, fixed between 1–3 hours after insemination, and examined by transmission electron microscopy. Membrane fusion had occurred in one ovum 2 hours after insemination, and the oocyte had resumed maturation and was at anaphase II of meiosis. Cortical granules had been exocytosed, and some of their contents were visible at the surface close to the oolemma all around the oocyte. The sperm that fused with this oocyte was acrosome-reacted and had been partly incorporated into the ooplasm, while the anterior two-thirds of its head was phagocytosed by a tongue of cortical ooplasm. Membrane fusion had occurred between the oolemma and the plasma membrane overlying the postacrosomal segment of the sperm head, posterior to the equatorial vestige. Sperm chromatin had not decondensed, and serial sections revealed a midpiece attached to the basal plate and a tail located deeper in the ooplasm, all devoid of plasma membrane. Supplementary sperm penetrating the inner zona, approaching the perivitelline space, had undergone the acrosome reaction but had a persistent vestige of the equatorial segment of the acrosome with intact plasma membrane. Evidence of sperm chromatin decondensation was seen in other oocytes, 3 hours after insemination, which were at telophase II of meiosis. Eight oocytes penetrated by sperm were monospermic, while four were unfertilized. The general pattern of sperm fusion and incorporation appears to conform to that seen in most other mammals. The study also reveals that sperm have to complete the acrosome reaction before fusing with the egg.     

Effect of Ca2+ channel antagonists on the acrosome reaction of guinea pig and golden hamster spermatozoa

The effects of Ca²⁺ channel antagonists on the motility and acrosome reaction of guinea pig spermatozoa were examined by incubating the spermatozoa continuously in Ca²⁺-containing capacitating media with 10^?6 M to 10^?4 M antagonist. Antagonists tested were four voltage-gated Ca²⁺ channel antagonists (verapamil, nifedipine, nimodipine, and FR–34235) and two ligand-gated channel antagonists (NaNO₂ and Na-nitroprusside). None of these antagonists could block the acrosome reaction. Instead, three antagonists (verapamil, nimodipine, and FR-34235, each at 10^?4 M) accelerated the onset of the acrosome reaction with a subsequent decrease in sperm motility. Nifedipine and Na-nitroprusside at the same concentration caused a complete loss of sperm motility by 4 hr of incubation with no substantial effect on the rate of acrosome reaction. The detrimental effect of antagonists on the motility of spermatozoa appears to be due to a direct, Ca²⁺-independent, membrane-perturbing action of the reagents. The acrosome reaction was not inhibited when guinea pig spermatozoa were precapacitated in Ca²⁺-free medium (with a low concentration of lysolecithin) in the continuous presence of antagonists. An acceleration of the onset of the acrosome reaction by verapamil (10^?4 M) was also demonstrated in the golden hamster. These results may be interpreted as indicating that the entry of extracellular Ca²⁺ into spermatozoa, which triggers the acrosome reaction of guinea pig and hamster spermatozoa, is not mediated by Ca²⁺ channels. This is in marked contrast with the case reported in invertebrate spermatozoa. Possible mechanisms by which some of the antagonists stimulate the acrosome reaction and affect the motility of mammalian spermatozoa are discussed.     

A minimum mechanism for Na+−Ca++ exchange: Net and unidirectional Ca++ fluxes as functions of ion composition and membrane potential

Summary Both simultaneous and consecutive mechanisms for Na⁺–Ca⁺⁺ exchange are formulated and the associated systems of steady-state equations are solved numerically, and the net and unidirectional Ca⁺⁺ fluxes computed for a variety of ionic and electrical boundary conditions. A simultaneous mechanism is shown to be consistent with a broad range of experimental data from the squid giant axon, cardiac muscle and isolated sarcolemmal vesicles. In this mechanism, random binding of three Na⁺ ions and one Ca⁺⁺ on apposing sides of a membrane are required before a conformational change can occur, translocating the binding sites to the opposite sides of the membranes. A similar (return) translocation step is also permitted if all the sites are empty. None of the other states of binding can undergo such translocating conformational changes. The resulting reaction scheme has 22 reaction steps involving 16 ion-binding intermediates. The voltage dependence of the equilibrium constant for the overall reaction, required by the 31 Na⁺Ca⁺⁺ stoichiometry was obtained by multiplying and dividing, respectively, the forward and reverse rate constants of one of the translocational steps by exp(–FV/2RT). With reasonable values for the membrane density of the enzyme (120 sites m²) and an upper limit for the rate constants of both translocational steps of 10⁵·sec^–1, satisfactory behavior was obtainable with identical binding constants for Ca⁺⁺ on the two sides of the membrane (10⁶ m ^–1), similar symmetry also being assumed for the Na⁺ binding constant (12 to 60m ^–1). Introduction of order into the ion-binding process eliminates behavior that is consistent with experimental findings.     

Gleichgewichtsbewegungen von Blättern als Reaktion auf asymmetrische Belastung — Isoklinotropismus nach Härdtl (1927) — und ihre Beziehung zum Gravitropismus

1. Die anscheinend in Vergessenheit geratenen älteren Angaben von HÄRDTL (1927 und spärer) und PRINGSHEIM (1931), nach denen einseitig belastete Blätter Gleichgewichtsbewegungen ausführen können (Isoklinotropismus nach HÄRDTL), wurden an mehreren Arten (Chelidonium majus, Aegopodium podagra ria, Ranunculus repens, Sambucus nigra, Coleus blumei und Hibiscus rosa sinensis) bestätigt,— Die einseitige Belastung erfolgte durch Einstecken von Nadeln in die eine Hälfte der Blattspreite bzw. in eine Blattfieder. 2. Bei Blättern, die in Spreite oder Stiel epinastisch gekrtimmt sind (die überwiegende Mehrzahl) oder auch durch die Belastung abwärts gebogen sind, kommt es dabei zu zwei verschiedenen Reaktionen: a) zu einer sofort eintretenden rein physikalischen reversiblen Reaktion, da die einseitige Last eine Torsion der Spreite bewirkt, die die Spreitenspitze nach der der Last gegenüberliegenden Seite [führt, und b) zu einer spärer eintretenden physiologischen Reaktion durch eine Wachstumskrümmung nach derselben Seite, - Beide Komponenten der Bewegung ftihren zu einer Verringerung oder einem Ausgleich des Ungleichgewichtes. 3. Die physiologische Reaktion war meist nach einem oder einigen Tagen erkennbar, bei Chelidonium mitunter schon nach einigen Stunden, bei Hibiscus gelegentlich erst nach etwa einer Woche. Mitunter blieb die Reaktion auch aus. Bei den gefiederten Blattern erfolgte sie in der Rhachis, ober- und unterhalb der belasteten Fieder, mitunter auch im Blattstiel, bei Coleus im Spreitengrund und im Blattstiel, bei Hibiscus im oberen Gelenkpolster (“Sekundargelenk”) des Blattstiels. Auch ältere Blätter reagierten oft noch überraschend gut. Vielfach führte die physiologische Reaktion zu einer vollständigen Ausbalancierung der einseitig belasteten Blattspreite. Auf nachtragliche Entfernung der eingesteckten Nadeln gingen auch die Krtimmungen in 2–3 Tagen wieder weitgehend zurück. 4. Als Ursache ftir die Gleichgewichtsbewegungen der Blätter kommen zwei verschiedene Mechanismen in Betracht: a) Infolge der durch die einseitige Belastung hervorgerufenen Schräglage der Blattspreite sammelt sich das Auxin auf der tiefer liegenden Flanke von Mittelnerv bzw. Rhachis und Blattstiel an, was zu einem stärkeren Wachstum dieser Seite und einer Gleichgewichtskrümmung führen muß. Nach dieser Auffassung ordnet sich der Isoklinotropismus dem Gravitropismus ein. b) Die nach der Belastung sofort eintretende auf der Torsionsspannung beruhende rein physikalische und zunächst reversible Gleichgewichtsreaktion des Blattes wird nach einigen Stunden oder Tagen teilweise irreversibel. (Für die spannungsfreien Abschnitte der Rhachis eines gefiederten Blattes oberhalb der Belastung kann diese Erklärung natürlich nicht gelten). Vermutlich sind beide Mechanismen, vor allern wohl der erstgenannte, bei den einzelnen Arten in verschiedenem Maße, als Ursache der Gleichgewichtsbewegungen wirksam. 5. Der biologische Sinn der Ausbalancierung eines (größeren) Blattes (PRINGSHELM 1931, HÄRDTL 1927, 1937 a) liegt darin, daß a) ein ausbalanciertes Blatt den geringsten Aufwand an mechanischen Elementen erfordert, und b) Photo- und Gravitropismus nur ein ausbalanciertes Blatt ohne Komplikationen in die angestrebte Lage fuhren konnen.     

一种快速、灵敏的血小板释放功能检测方法及其在抗血小板药物研究中的应用

本文报道了一种快速、灵敏的血小板释放功能检测方法:利用荧光素-荧光素酶在有ATP、Mg~(2+)、O_2存在时产生的生物发光素测定血小板ATP的释放量,以反映血小板的释放功能;研究了ADP、AA、胶原、凝血酶等四种诱导剂对血小板释放功能的作用,发现ADP的诱导释放能力较其他三者为弱;观察在不同剂量ADP和AA的诱导下,血小板聚集强度和释放能力之间的关系,研究了血小板数等因素对ATP释放功能测定的影响。应用该方法研究了Aspirin及活血化淤药物川芎嗪,毛冬青甲素对血小板释放功能的影响,发现Aspirin对AA诱导的释放反应有强烈的抑制作用。在以ADP诱导的释放反应中,川芎嗪的抑制作用较毛冬青甲素更为强烈。