DQ α and β RFLP reveals the composition of the DQ molecule recognized by T-cell clones

Pst I RFLP, revealed with DQ and DQ probes, was compared with Taq I RFLP using a panel of DR-homozygous cell lines and HLA-typed family members. Taq I patterns, characteristic for each DR-associated DQ and allelic forms, were recognized in the homozygous state and then proven to segregate in the heterozygous members of informative families. The presence of both specific and chains was found to be necessary to form the type of DQ molecule specifically recognized by two alloreactive T-cell clones. Particular and associations also seem to be responsible for some Dw splits of the DRw6-positive cells. Taq I RFLP analysis may be more complex than the Pst I analysis, but is certainly more informative and complete, considering the type of information we were seeking by performing these types of experiments.Abbreviations used in this paper BSA bovine serum albumin - GLO glyoxalase - kb kilobase(s) - LCL lymphoblastoid cell line - MHC major histocompatibility complex - PBL peripheral blood lymphocyte - PLT primed lymphocyte test - RFLP restriction fragment length polymorphism - SDS sodium dodecyl sulfate - SSC standard sodium citrate - SSCP sodium, sodium citrate, sodium phosphate - TBE Tris-borate, boric acid, ethylenediaminetetraacetate (EDTA) - TCGF T-cell growth factor     

Antral gastrin- and somatostatin-producing cells and intraluminal peptide secretion in normal subjects and duodenal ulcer patients with and without vagotomy

The behaviour of gastrin (G) cells and somatostatin (D) cells in endoscopic antral biopsies and that of intraluminal gastrin (ILG) and somatostatin (ILS) release in the gastric juice were investigated in three groups of patients: control subjects, duodenal ulcer (DU) patients and DU patients treated by a superselective vagotomy (SSV). G and D cell densities were correlated in the three groups of subjects. The G/D cell ratio was significantly increased in SSV patients (P less than 0.001) as compared to control and DU patients. No correlation was found between gastrin or somatostatin cell densities and basal intraluminal levels of the two peptides. ILG output was significantly higher in DU patients than in control or SSV patients (P less than 0.001). ILS output was also higher in DU patients than in controls (P less than 0.001) and in SSV patients (P less than 0.05). It was also significantly augmented in SSV (P less than 0.001) as compared to control patients. ILG and ILS concentrations were only correlated in controls. Within each of the three groups of subjects, ILG and ILS release varied in function of the gastric juice pH. Our results emphasize the necessity to consider the intragastric pH as well as the physiological or pathological state to study intraluminal peptides in man.     

水蒸汽蒸馏巴柑檬叶和果皮精油化学成分的研究

巴柑檬是我们第一次从国外引种成功的一种名贵香料植物。用色谱-质谱-计算机联用技术、毛细管气相色谱保留指数法和标准品叠加法分析了水蒸汽蒸馏巴柑檬叶和果皮精油的化学成分。从叶和果皮精油分离出来的220个和200个成分中,分别鉴定出48个和57个成分。鉴定组分的含量分别占叶和果皮精油的99.80％和98.54％。叶精油与果皮精油在化学成分方面的主要区别是叶油中萜烃化合物含量较低,而萜醇类化合物含量较高。     

云南壮异蝽属及娇异蝽属新种记述(半翅目:异蝽科)

云南地区的壮异蝽属(Urochela Dallas)和娇异蝽属(Hrostylis Westwood)截止到目前共记录23种。本文记述了在该省西部地区发现的5新种,现描述如下。模式标本保存于天津南开大学生物系。 钩壮异蝽Urochela hamata,新种(图1,2) 体黄褐色,具黑褐色花斑及黑色刻点。触角第4节中部及第5节基半部为淡黄色;     

Establishment of mutant murine mammary carcinoma FM3A cell strains transformed with the herpes simplex virus type 2 thymidine kinase gene

To establish cell systems appropriate for investigating the mode of action of antiherpetic nucleoside analogues, mutant cell strains were constructed from murine mammary carcinoma FM3A cells, which were deficient in TK, but were transformed with a recombinant plasmid DNA containing the HSV-2 TK gene. The transformed cells incorporated the viral DNA, expressed viral TK activity and showed unusually high sensitivity to the cytostatic action of the antiherpetic nucleoside analogues ACV and IVDU, both of which were only weakly inhibitory to the growth of the parent cells. Curiously, the FM3A cell strains transformed with HSV-2 TK gene showed a higher sensitivity to ACV and IVDU than the previously established cell line transformed with HSV-1 TK gene. This contrasts with the inhibitory effects of ACV and IVDU on acute HSV infection, since HSV-2 infection is slightly or considerably less susceptible than HSV-1 infection to inhibition by ACV or IVDU, respectively.     

Oxidation-reduction properties of the electron acceptors of Photosystem II I. Redox titration of the flash-induced carotenoid band shift,of C550 and of the variable fluorescence yield in spinach chloroplasts

Redox titration of the electrochromic carotenoid band shift, detected at 50 μs after a saturating actinic flash, in spinach chloroplasts, shows that only one electron acceptor in Photosystem II participates in a transmembrane primary electron transfer. This species, the primary quinone acceptor, Q, shows only one midpoint potential (E_m,7.5) of approx. 0 V and is undoubtedly equivalent to the fluorescence quencher, Q_H. A second titration wave is observed at low potential ($\text{E}{}_{\mathrm{<mtext>m</mtext><mtext>,7.5</mtext>}}\text{? ? 240}\text{mV}$) and at greater than 3 ms after a saturating actinic flash. This wave has an action spectrum different from that of Photosystem II centers containing Q and could arise from a secondary but not primary electron transfer. A low-potential fluorescence quencher is observed in chloroplasts which largely disappears in a single saturating flash at ? 185 mV and which does not participate in a transmembrane electron transfer. This low-potential quencher (probably equivalent to fluorescence quencher, Q_L) and Q are altogether different species. Redox titration of C550 shows that if electron acceptor Q_β is indeed characterized by an E_m,7 of + 120 mV, then this acceptor does not give rise to a C550 signal upon reduction and does not participate in a transmembrane electron transfer. This titration also shows that C550 is not associated with Q_L.     

Oxidation-reduction properties of the electron acceptors of Photosystem II. II. Redox titration at various pH values of the flash-induced formation of C550 in Chlamydomonas Photosystem II particles lacking the secondary quinone electron acceptor

Redox titrations of the flash-induced formation of C550 (a linear indicator of Q^?) were performed between pH 5.9 and 8.3 in Chlamydomonas Photosystem II particles lacking the secondary electron acceptor, B. One-third of the reaction centers show a pH-dependent midpoint potential (E_m,7.5) = ? 30 mV) for redox couple $\text{Q}\text{Q}{}^{\mathrm{?}}$, which varies by ?60 mV/pH unit. Two-thirds of the centers show a pH-independent midpoint potential (E_mm = + 10 mV) for this couple. The elevated pH-independent E_m suggests that in the latter centers the environment of Q has been modified such as to stabilize the semiquinone anion, Q^?. The midpoint potentials of the centers having a pH-dependent E_m are within 20 mV of those observed in chloroplasts having a secondary electron acceptor. It appears therefore that the secondary electron acceptor exerts little influence on the E_m of $\text{Q}\text{Q}{}^{\mathrm{?}}$. An EPR signal at g 1.82 has recently been attributed to a semiquinone-iron complex which comprises Q^?. The similar redox behavior reported here for C550 and reported by others (Evans, M.C.W., Nugent, J.H.A., Tilling, L.A. and Atkinson, Y.E. (1982) FEBS Lett. 145, 176–178) for the g 1.82 signal in similar Photosystem II particles confirm the assignment of this EPR signal to Q^?. At below ?200 mV, illumination of the Photosystem II particles produces an accumulation of reduced pheophytin (Ph^?). At ?420 mV Ph^? appears with a quantum yield of 0.006–0.01 which in this material implies a lifetime of 30–100 ns for the radical pair P-680⁺Ph^?.     

Activity of central neurons of the electroreceptor system ofGlyptosternum reticulatum

Two types of electroreceptive neurons — tonic and phasic — were found in acute experiments with extracellular recording of unit activity from the lateral lobes of the medulla in the Turkestan catfishGlyptosternum reticulatum. Tonic neurons were more sensitive to the potential gradient in water (the threshold for most neurons was 1–6 µV/cm) than phasic neurons, they possessed spontaneous activity (mean frequency 4–10 spikes/sec), and their response characteristics depended significantly on the intensity and duration of stimulation. Phasic neurons had no spontaneous activity; their sensitivity was about one order of magnitude lower than that of the tonic neurons, and the response was independent of the parameters of the stimuli. The probable mechanisms of differentiation of neurons into two types, with a possible link with the characteristics of the receptor formations or with the functional organization of the corresponding brain centers, are discussed.     

Kinetics of the sodium current through EDTA-modified calcium channels of the molluscan neuron somatic membrane

The kinetics of the slow current carried by sodium ions through potential-dependent calcium channels after addition of EDTA to calcium-free external solution was investigated in experiments by the intracellular dialysis method on isolatedHelix pomatia neurons. The activation kinetics of this current was similar to that of the calcium current and could be described by the use of the square of the activation variable m in Hodgkin-Huxley equations. The decay (inactivation) kinetics of the induced sodium current during prolonged depolarization is biexponential in character. It is suggested that decay of the sodium currents takes place as a result of two independent processes: potential-dependent inactivation with a time constant τ_h～1 sec, taking place as far as a certain steady-state level h_∞, and a decrease in current connected with Na⁺ accumulation inside the cell during passage of the current and a consequent change in the sodium electrochemical potential (τ_c～10 sec). It is concluded that modification of the calcium channels, so that they acquire the ability to conduct sodium, has no significant effect on the gating mechanisms responsible for opening and closing of the channels.