Resolution of pheromone pulses in receptor cells of Antheraea polyphemus at different temperatures

The ability of pheromone receptor cells of male Antheraea polyphemus (Saturniidae) to resolve stimulus pulses was determined at different temperatures (8°, 18°, 28°C). The cells were stimulated by repeated 20-ms puffs of the pheromone components (E, Z)-6, 11-hexadecadienyl acetate and (E, Z)-6,11-hexadecadienal. At higher temperatures, higher frequencies of stimulus pulses were resolved by the nerve-impulse response: about 1.25 pulses per second at 8°C, 2.5 pulses/s at 18°C and 5 pulses/s at 28°C. The decreased ability of receptor cells to resolve stimulus pulses at low temperatures may reduce the male moth's chance of reaching the pheromone source. The peak nerve-impulse frequency increased whereas the duration of nerve-impulse responses to single stimulus pulses decreased at higher temperatures. At a given temperature and stimulus intensity the peak nerveimpulse frequency decreased with shorter intervals between the stimulus pulses, but the duration of the responses remained almost constant. The time needed for recovery from adaptation caused by a single stimulus pulse was longer at lower temperatures. The aldehyde receptor cell recovered more quickly than the acetate cell. At low stimulus concentration, the resolution ability of the acetate cell was strongly decreased, whereas in the aldehyde cell it was only slightly impaired.     

Conservation of the alternative oxidase and enhancement of cyanide-resistant respiration in suspension-cultured pear fruit cells by inhibitors of macromolecular synthesis

The contribution of the alternative pathway to the respiration of suspension-cultured pear ( Pyrus communis cv. Passa Crasanne) cells was enhanced, often severalfold, within 2 to 4 days following the addition of cycloheximide, actinomycin D, or 2-(4-methyl-2,6-dinitroanalino)- N -methyl propionamide (D-MDMP). Concomitant inhibition of cellular protein synthesis by cycloheximide and actinomycin D was transient and incomplete. However, inhibition by D-MDMP was virtually complete (>97%) and persisted over several days. [³⁵S]-labelling and polyacrylamide gel separation indicated that cycloheximide precluded the appearance of discernable new proteins in mitochondria. Probes with monoclonal antibodies revealed a conservation of alternative oxidase protein levels in the mitochondria of inhibitor-treated cells. The data, appraised within the complexities of cell-culture dynamics, lead to the conclusion that the observed increases in capacity for cyanide-resistant respiration are the consequence, likely indirect, of inhibited protein synthesis with resultant retention and activation of constitutive alternative oxidase.     

Effect of Z-100, an immunomodulator extracted from human type tubercle bacilli,on the pulmonary metastases of lewis lung carcinoma in attempt to regulate suppressor T cells and suppressor factor,IL-4

In the present study, anti-metastatic effect of Z-100 on the spontaneous pulmonary metastases of Lewis lung carcinoma (3LL) was examined in an attempt to regulate suppressor T cells. When Z-100 (10 mg/kg) was daily injected i.p. after 3LL inoculation, survival rate of these mice was increased significantly (p<0.05). In addition, the number of pulmonary metastatic colonies of 3LL in Z-100-treated mice were significantly decreased by 38% at 21 days, as compared with that of control mice (p<0.05). Along with the decrease of pulmonary metastases, suppressor cell activity was also gradually reduced in these mice, as compared with that of control mice. When splenic suppressor cells (5×10⁷ cells) from 3LL-bearing mice were adoptively transferred into normal mice (recipients) just before inoculation of 3LL, the development of pulmonary metastases in recipients was significantly accelerated. However, splenocytes from 3LL-bearing mice treated with Z-100 did not affect the development of pulmonary metastasis. The potential to accelerate the metastasis of splenic mononuclear cells from 3LL-bearing mice was decreased significantly by the treatment with anti-Thy 1.2 monoclonal antibody (mAb), anti-Lyt 2.2 mAb or anti-CD11b mAb followed by complement. IL-4 activity in the sera of 3LL-bearing mice was detected 15 days after tumor inoculation (13 pg/ml) and gradually increased (18 pg/ml) 20 days after tumor inoculation. However, when Z-100 (10 mg/kg) was daily injected i.p., IL-4 activity in sera was decreased significantly, and the IL-4 activity was not detected in these mice on day 20. These results suggest that Z-100 could inhibit the pulmonary metastases in 3LL-bearing mice through the inhibition of suppressor T cell activity and a possible candidate of its effector molecule, IL-4.     

Peroxyoxalate chemiluminescent assay for oxidase activities based on detecting enzymatically formed hydrogen peroxide

A sensitive peroxyoxalate chemiluminescent (PO-CL) assay for activities of oxidases (uricase, choline oxidase, cholesterol oxidase and xanthine oxidase) which catalyse a formation of hydrogen peroxide was developed using 4,4′-oxalyl-bis[(trifluoromethylsulphonyl)imino]trimethylene-bis(4-methylmorpholinium)trifluoromethanesulphonate as a chemiluminogenic reagent and 2,4,6,8-tetramorpholinopyrimido[5,4-d]pyrimidine as a fluorophore. The standard curve for hydrogen peroxide was linear over the range 1 × 10^?7-1 × 10^?4 mol/L. Relative standard deviations for oxidase assays were 5.1–12.7% (n = 10). Detection limits were 1 × 10^?3 U/mL for uricase, 5 × 10^?4 U/mL for choline oxidase, 5 × 10^?3 U/mL for cholesterol oxidase and 5 × 10^?4 U/mL xanthine oxidase (sample to blank ratio, 3).     

一种“无血清”培养基对肿瘤细胞生长的支持

本文报告一种为适于杂交瘤细胞生长“无血清”培养基－适量的成牛血清低分子成分超滤液、１０ｍｇ／Ｌ转铁蛋白（Ｔ）、１０ｍｇ／Ｌ胰岛素（Ｉ）、２０μｍｏｌ／Ｌ乙醇胺（Ｅ）、４０ｎｍｏｌ／Ｌ硒酸钠（Ｓ）等诸补充成分替代胎牛血清加到基础液中－也完全适用于培养肿瘤细胞,且观察到与之相似的规律性结果,癌细胞在本“无血清”培养若的生长水平达到在含胎牛血清培养基中生长的水平。对于癌细胞的生长,ＬＭＷ－ＣＳ与Ｔ、Ｉ、     

Comparative studies on the dynamics of crosslinked insulin

Molecular dynamics simulations were carried out on an insulin crosslinked between the N-terminal A chain and the C-terminal B chain to form a so-called mini-proinsulin: N -^A1-N -^B29-diaminosuberoyl insulin (DASI). To investigate the influence of crosslinking on the dynamics of the insulin moiety, the bridge was removed from a transient DASI structure and simulation was carried on independently with the then unlinked (ULKI) as well as with the crosslinked species. The effects of crystal packing and quaternary interactions were checked by simulating both types of monomers and dimers known from the hexamer structure. All simulations were compared to previous ones of native insulin. DASI shows general similarity to the native simulations in most parts of the structure. Deviations are visible in the segments to which the bridge is directly connected, i.e. their flexibility is reduced. Upon removal of the bridge the ULKI simulations reapproach those of native insulin. The influence of the bridge spreads over the whole molecule, but all of its main structural features remain intact. The simulations suggest that the displacement of the C-terminal B chain of native insulin, considered important for receptor interaction, is prevented by the bridge, which also partially shields some binding residues. This is in accordance with the poor biological potency of A1-B29-crosslinked insulins.Abbreviations DASI-insulin(DASI) bovineN -^A1-N -^B29-di-aminosuberoyl insulin - ULK-insulin (ULKI) Native beef insulin with the bridge of DASI removed     

Inhibition of the mitochondrial Ca2+ uniporter by pure and impure ruthenium red

Commercial ruthenium red is often purified by a single recrystallization as described by Luft, J.H. (1971) Anat Rec 171, 347–368, which yields small amounts of material having an apparent molar extinction coefficient of 67,400 at 533 nm. A simple modification to the procedure dramatically improves the yield, allowing crystallization to be repeated. Three times recrystallized ruthenium red has an apparent extinction coefficient of 85,900, the highest value reported to date. Both crude and highly purified ruthenium red can be shown to inhibit reverse activity of the mitochondrial Ca²⁺ uniporter (uncoupled mitochondria), provided that care is taken to minimize and account for Ca²⁺ release through the permeability transition pore. Crude ruthenium red is 7–10 fold more potent than the highly purified material in this regard, on an actual ruthenium red concentration basis. The same relative potency is seen against forward uniport (coupled mitochondria), however, the I₅₀ values are 10 fold lower for both the crude and purified preparations. These data demonstrate unambiguously that the energy state of mitochondria affects the sensitivity of the Ca²⁺ uniporter to ruthenium red preparations, and that both the forward and reverse reactions are subject to complete inhibition. The data suggest, however, that the active inhibitor may not be ruthenium redper se, but one or more of the other ruthenium complexes which are present in ruthenium red preparations.Abbreviations CCP carbonyl cyanide p-chlorophenylhydrazone - CSA cyclosporin A - Hepes 4-(2-hydroxyethyl)-1-piperazine ethanesulfonic acid     

A comparative study of the glomerular peripolar cell and the renin-secreting cell in twelve mammalian species

The peripolar cell is a glomerular epithelial cell situated within Bowman's capsule at its vascular pole. It is believed to be a secretory cell which forms part of the juxtaglomerular apparatus. Scanning electron microscopy was used to perform a comparative study of the morphology and number of peripolar cells in twelve mammalian species. The number of renin-secreting cells in kidney sections stained by renin antibodies and immunocytochemistry was counted. There was a marked inter-species variation in the number, size and appearance of peripolar cells. They were largest and most abundant in sheep and goat and fewest in dog, cow and human. There was no correlation between the numbers of peripolar cells and renin-secreting cells. This does not support the view that the peripolar cell is part of the juxtaglomerular apparatus.     

Loss of intracellular glycerol from Dunaliella by electroporation at constant osmotic pressure: subsequent restoration of glycerol content and associated volume changes

The effect of electroporation on Dunaliella tertiolecta at constant osmotic pressure (or water activity) was investigated. The following metabolic and physiological parameters were determined: extracellular and intracellular glycerol content, soluble protein content, photosynthetic oxygen evolution, mitochondrial oxygen uptake, cell volume and cell density. Electroporation conditions are described that released about 10% of intracellular glycerol to the external medium with minimal apparent effects on metabolism. Glycerol release originated from most cells rather than by total rupture of a small proportion of cells. Cell volume, measured on motile cells by video microscopy, reduced by 23% immediately after electroporation. Cell density did not increase. The uptake of mannitol, the major solute in the electroporation medium, was less than 20% of glycerol release. Following electroporation, the intracellular glycerol content and the cell volume both returned to pre-electroporation values after about 30min. Because the cells were maintained at constant external osmotic pressure throughout the procedure, it is concluded that the regulatory mechanism responsible for setting the intracellular glycerol content does not sense external osmotic pressure per se. These findings are consistent with a mechanism that senses a parameter linked directly to cell volume to set the intracellular glycerol content.