A/California/7/2009与A/California/4/2009病毒感染力比较

目的甲型H1N1流感病毒A/California/7/2009与A/California/4/2009病毒序列比较同源性在99%以上,本实验旨在比较两株病毒感染BALB/c小鼠研究感染力强弱。方法分别将A/California/7/2009（CA7）与A/California/4/2009（CA4）两株病毒分别连续10倍稀释后,对4~6周龄雌性BALB/c小鼠经乙醚麻醉后进行滴鼻攻毒,每个稀释度接种10只实验小鼠,测定CA7 MLD50为101.24/0.05 mL,检测小鼠感染、致病的多项指标,观察期为14 d。结果相同TCID50的CA7和CA4病毒感染小鼠,CA4感染小鼠后14 d内死亡率为20%,而CA7感染小鼠后8 d内死亡率为100%。CA7 106TCID50感染的小鼠病理表现为重度弥漫性间质性肺炎,CA4 106TCID50感染的小鼠病理表现为中度-重度间质性肺炎。结论在相同条件下,CA7感染力明显强于CA4。     

Preparation of copoly (γ-benzyl-l-glutamyl-N5-β-d-glucopyranosyl-l-glutamine) and its interaction with fibroblast cells

Copoly(α-amino acid)s consisting of γ-benzyl-l-glutamate and $\text{N}{}^5\text{-β-}\text{d}\text{-glucopyranosyl-}\text{l}\text{-glutamine}$ were prepared by the reaction of copoly(l-glutamate) containing succinimide ester, which served as active site for the coupling reaction with β-d-glucopyranosylamine. The α-helical conformation of these copolymers became unstable in DMF as the content of glutamine derivative increased. A dry film made from this copolymer could take a full α-helical conformation even at such a high content as 80% of the glutamine derivative, but in a wet film this ordered structure was partially disrupted by hydration. The hydraulic permeability of this copoly(α-amino acid) was clearly dependent on the molar content of glucopyranosyl groups. The attachment of fibroblast cells to these hydrated copolymer films was effectively depressed in the presence of a serum-free medium. The cells attached to the substrate were spherical in shape.     

Metabolism of Δ4-cis-PGF1α in the monkey

This isomer of PGF_2α is relatively resistant to metabolic degradation in the Cynomolgus monkey. Thus, 16–20 per cent of the amount injected was excreted unchanged in the urine. Five metabolites with 20, 18, 16 and 14 carbon atoms in the skeleton were identified. The data are similar to those earlier seen in the rat and further support the idea that this analogue of PGF_2α could have a long half-life time in the mammalian body and thus a long duration of its pharmacological actions.     

Conformational studies on poly(N-δ-trimethyl-l-ornithine)

$\text{Poly}\text{(N-δ-}\text{trimethyl-}\text{l}\text{-ornithine}$), (Me₃Orn)_n, is usually not able to attain the α-helical conformation in aqueous solution independent of its pH value; however, it becomes α-helical at low concentrations of sodium perchlorate over a wide pH range according to the circular dichorism (c.d.) spectra. Cl^?, SO₄^2? and H₂PO₄^? do not induce α-helix formation. One can conclude that a distinct topology of the anions bound by the side chains is responsible for the α-helix-inducing effect of some water-structure-breaking anions such as perchlorate. This means that the anions are inserted between the ?N⁺ of the side groups shielding the positive charges repelling one another. The insertion of the anions requires that the water molecules surrounding the ions can be stripped off, which is easily possible if they are water-structure-breaking ones. At higher perchlorate concentrations, the c.d. spectrum changes. It is characterized by a negative shoulder near 208 nm and a pronounced minimum at ≈ 226 nm. With increasing temperature, the c.d. spectrum of the α-helix occurs. Finally the α-helix undergoes a conformational change to the random coil. The apparent transition enthalpy ΔH_vH is remarkably lower than that of the homologue (Me₃Lys)_n, obviously due to a lower cooperativity of the transition. In contrast to poly(l-ornithine), (Orn)_n, the c.d. spectrum of (Me₃Orn)_n remains almost unchanged after adding anionic surfactants such as sodium octyl sulphate (SOS) or sodium dodecyl sulphate (SDS). In organic solvents like methanol or isopropanol, in contrast to (Orn)_a and (Lys)_n, no α-helix formation occurs. However, in mixtures of these alcohols or dioxane with water, α-helix formation is induced by perchlorate, as in pure water. The thermal stability of the α-helix in these systems is increased.     

Dissimilatory nitrate uptake in Paracoccus denitrificans via a Δ\̃gmH+-dependent system and a nitrate-nitrite antiport system

Respiration-driven proton translocation has been studied with the oxidant pulse method for cells of denitrifying Paracoccus denitrificans oxidizing H₂ during reduction of O₂, NO^?₃, NO^?₂ or N₂O. A simplified scheme of anaerobic electron transport and associated proton translocation is shown that is consistent with the measured $\text{H}{}^{\mathrm{+}}\text{oxidant ratios}$. Furthermore, the kinetics and energetics of NO^?₃ uptake in whole cells of P. denitrificans were studied. For this purpose, we measured H₂ consumption or N₂O production after addition of NO^?₃ to a cell suspension, which indirectly gave information about uptake (and reduction) of NO^?₃. It was found that a lag phase in H₂ consumption or N₂O production appeared whenever the membrane potential was dissipated by addition of thiocyanate, carbonyl cyanide m-chlorophenylhydrazone or triphenyl-methylphosphonium bromide. However, these lag phases were not observed when NO^?₂ was present at the moment of introduction of NO^?₃. On the basis of these findings we conclude that there are two uptake systems for NO^?₃. One system is dependent on the proton-motive force and is probably used for initiation of NO^?₃ uptake. The other is an $\text{NO}{}^{\mathrm{?}}{}_3\text{NO}{}^{\mathrm{?}}{}_2$ antiport and its function is to take over NO^?₃ uptake from the first system.     

Comparison of red cell and kidney (Na+ + K+)-ATPase at 0°C

Human red cell and guinea pig kidney $\text{(}\text{Na}{}^{\mathrm{+}}\text{+}\text{K}{}^{\mathrm{+}}\text{)-}\text{ATPase}$ were phosphorylated at 0°C. Using concentrations of ATP ranging from 10^?6 to 10^?8 M, ATP-dependent regulation of reactivity is observed with red cell but not kidney $\text{(}\text{Na}{}^{\mathrm{+}}\text{+}\text{K}{}^{\mathrm{+}}\text{)-}\text{ATPase}$ at 0°C. In particular, with the red cell enzyme only, the following are observed: (i) the ratio of enzyme-bound ATP (E·ATP, measured by the pulse-chase method of Post, R.L., Kume, S., Tobin, T., Orcutt, B. and Sen, A.K. (1969) J. Gen. Physiol. 54, 306s-326s) to steady-state level of total phosphoenzyme (EP) decreases with decrease in ATP concentration and (ii) the apparent turnover of phosphoenzyme (ratio of Na⁺-stimulated ATP hydrolysis to level of total EP at steady state) also varies as a function of ATP concentration. In addition, when EP is formed at very low ATP (0.02 μM), and then EDTA is added, rapid disappearance of a fraction of EP occurs, presumably due to ATP resynthesis, only with the red cell enzyme. These differences in behaviour of the red cell and kidney enzymes are explained on the basis of the observed predominance of K⁺-insensitive EP in red cell, but K⁺-sensitive EP in kidney $\text{(}\text{Na}{}^{\mathrm{+}}\text{+}\text{K}{}^{\mathrm{+}}\text{)-}\text{ATPase}$ at 0°C.     

Determination of H+e− ratios in chloroplasts with flashing light

Using a rapid pH electrode, measurements were made of the flash-induced proton transport in isolated spinach chloroplasts. To calibrate the system, we assumed that in the presence of ferricyanide and in steady-state flashing light, each flash liberates from water one proton per reaction chain. We concluded that with both ferricyanide and methylviologen as acceptors two protons per electron are translocated by the electron transport chain connecting Photosystem II and I. With methyl viologen but not with ferricyanide as an acceptor, two additional protons per electron are taken up due to Photosystem I activity. One of these latter protons is translocated to the inside of the thylakoid while the other is taken up in H₂O₂ formation. Assuming that the proton released during water splitting remains inside the thylakoid, we compute $\text{H}{}^{\mathrm{+}}\text{e}{}^{\mathrm{?}}$ ratios of 3 and 4 for ferricyanide and methyl viologen, respectively.In continuous light of low intensity, we obtained the same $\text{H}{}^{\mathrm{+}}\text{e}{}^{\mathrm{?}}$ ratios. However, with higher intensities where electron transport becomes rate limited by the internal pH, the $\text{H}{}^{\mathrm{+}}\text{e}{}^{\mathrm{?}}$ ratio approached 2 as a limit for both acceptors.A working model is presented which includes two sites of proton translocation, one between the photoacts, the other connected to Photosystem I, each of which translocates two protons per electron. Each site presents a ≈ 30 ms diffusion barrier to proton passage which can be lowered by uncouplers to 6–10 ms.     

转录因子cpcR同源基因cpcR-c1和cpcR-t的功能鉴定

苏云金芽胞杆菌（Bacillus thuringiensis,Bt） LM1212菌株与典型的Bt菌株表型不同,可分化形成芽胞、形成细胞和晶体产生细胞。在LM1212菌株中,转录因子CpcR不仅参与了细胞分化过程,而且能够激活晶体蛋白基因cry35-like的启动子(P₃₅)。【目的】筛选cpcR同源基因,验证其生物学功能。【方法】本研究克隆了2个cpcR同源基因,来源于蜡样芽胞杆菌的cpcR-c1和来源于东洋芽胞杆菌的cpcR-t,将cpcR及其同源基因分别构建在pHT304-P₃₅-gfp、pHT304-P₃₅-lacZ报告载体上,获得的重组质粒转入无cpcR基因且无晶体蛋白基因的Bt HD73^–菌株中。利用激光共聚焦显微镜观察重组菌HD^–(cpcR-c1-P₃₅-gfp)和HD^–(cpcR-t-P₃₅-gfp)的细胞表型并进行芽胞计数实验。测定HD^–(cpcR-c1-P_35<...     

Characterization of a β-actinin-like protein in purified non-muscle cell membranes. Its activity on (Na+ + K+)-ATPase

Treatment by EDTA of purified plasma membranes from MF₂S cells (a variant of the murine plasmacytoma MOPC 173) solubilized proteins and increased by a 1000-fold the sensitivity of $\text{(}\text{Na}{}^{\mathrm{+}}\text{+}\text{K}{}^{\mathrm{+}}\text{)-}\text{ATPase}$ to ouabain. When added back with Ca²⁺ to treated plasma membranes, these EDTA-solubilized proteins restored the initial sensitivity of the enzyme to its inhibitor. We report the purification of a protein of $\text{M}{}_{\mathrm{<mtext>r</mtext>}}$ 32 000, isolated from the EDTA-treated membrane supernatant. This protein was purified by a one-step procedure involving a preparative polyacrylamide gel electrophoresis without detergent. In the presence of Ca²⁺ it was able to restore the original sensitivity to ouabain of $\text{(}\text{Na}{}^{\mathrm{+}}\text{+}\text{K}{}^{\mathrm{+}}\text{)-}\text{ATPase}$ from EDTA-treated membrane. This protein was shown to be similar to the β-actinin described by Maruyama by the following criteria: (1) molecular weight and amino acid composition; (2) cross-reactivity with their respective antisera; (3) in the presence of Ca²⁺ the same quantitative biological activity on ouabain sensitivity of the $\text{(}\text{Na}{}^{\mathrm{+}}\text{+}\text{K}{}^{\mathrm{+}}\text{)-}\text{ATPase}$. A possible interaction between β-actinin, calmodulin and membrane-bound $\text{(}\text{Na}{}^{\mathrm{+}}\text{+}\text{K}{}^{\mathrm{+}}\text{)-}\text{ATPase}$ is discussed.     

Investigation of the mechanism of temperature sensitivity of the electroreceptors of ampullae of lorenzini

In experiments on Black Sea skates (Raja clavata), the potential of the receptor epithelium of the ampullae of Lorenzini and spike activity of single nerve fibers connected to them were investigated during electrical and temperature stimulation. Usually the potential within the canal was between 0 and –2 mV, and the input resistance of the ampulla 250–400 k. Heating of the region of the receptor epithelium was accompanied by a negative wave of potential, an increase in input resistance, and inhibition of spike activity. With worsening of the animal's condition the transepithelial potential became positive (up to +10 mV) but the input resistance of the ampulla during stimulation with a positive current was nonlinear in some cases: a regenerative spike of positive polarity appeared in the channel. During heating, the spike response was sometimes reversed in sign. It is suggested that fluctuations of the transepithelial potential and spike responses to temperature stimulation reflect changes in the potential difference on the basal membrane of the receptor cells, which is described by a relationship of the Nernst's or Goldman's equation type.I. P. Pavlov Institute of Physiology, Academy of Sciences of the USSR, Leningrad. I. M. Sechenov, Institute of Evolutionary Physiology and Biochemistry, Academy of Sciences of the USSR, Leningrad. Pacific Institute of Oceanology, Far Eastern Scientific Center, Academy of Sciences of the USSR, Vladivostok. Translated from Neirofiziologiya, Vol. 12, No. 1, pp. 67–74, January–February, 1980.     

Principles of organization and evolution of systems of regulation of functions

Evolution of living organisms is closely connected with evolution of structure of the system of regulations and its mechanisms. The functional ground of regulations is chemical signalization. As early as in unicellular organisms there is a set of signal mechanisms providing their life activity and orientation in space and time. Subsequent evolution of ways of chemical signalization followed the way of development of delivery pathways of chemical signal and development of mechanisms of its regulation. The mechanism of chemical regulation of the signal interaction is discussed by the example of the specialized system of transduction of signal from neuron to neuron, of effect of hormone on the epithelial cell and modulation of this effect. These mechanisms are considered as the most important ways of the fine and precise adaptation of chemical signalization underlying functioning of physiological systems and organs of the living organism