Cytoplasmic Alkalization and Cytoplasmic Streaming Induced by Light and Histidine in Leaf Cells of Egeria densa: in vivo 31P-NMR study

Rotational streaming of the cytoplasm including chloroplastswas induced by L-histidine, as well as by light, on the anticlinalface of leaf cells of Egeria densa. In the case of treatmentwith L-histidine some of the chloroplasts remained stationaryon the periclinal face of cells after rotational cytoplasmicstreaming was initiated. However, these chloroplasts were easilydislodged and translocated to the centrifugal end of the histidine-treatedcells by application of a centrifugal force that barely affectedthe location of chloroplasts in cells incubated in the darkwithout L-histidine. This result indicates that the anchoringof chloroplasts was weakened by L-histidine. Thus only the releaseof chloroplasts from anchoring was not enough for initiationof their streaming. The cytoplasmic pH (pH_c) and vacuolar pH(pH_v) were noninvasively monitored by in vivo ³¹P-nuclear magneticresonance (NMR) spectroscopy. Compared with the dark controlvalue, both illumination and treatment with L-histidine increasedthe pH_c by 0.3 units. In contrast, pH_v changed only a littlewith both illumination and treatment with L-histidine. Releaseof chloroplasts from anchoring and initiation of cytoplasmicstreaming are discussed in relation to the increase in pH_c inducedby both light and L-histidine. ⁴ Present address: Department of Cell Biology, National Instituteof Agrobiological Resources, Kannondai, Tsukuba, Ibaraki, 305Japan ⁵ Present address: Marine Biotechnology Institute Co., Ltd.,Head Office, 2-35-10 Hongo, Bunkyo-ku, Tokyo, 113 Japan (Received July 16, 1990; Accepted December 20, 1990)     

Effects of compound eye-removal on the photoperiodic response of the band-legged ground cricket, Pteronemobius nigrofasciatus

The band-legged ground cricket Pteronemobius nigrofasciatus shows a clear photoperiodic response at 25°C with respect to the control of the induction of embryonic diapause. When crickets were reared under a short-day (LD 12 12) photoperiod and then transferred to a long-day (LD 16 8) photoperiod upon adult emergence, the adults mainly laid nondiapause eggs. However, adults maintained continuously under short-day conditions laid dispause eggs. When compound eyes were bilaterally removed after adult emergence, the crickets mainly laid nondiapause eggs, irrespective of the photoperiod. Thus, the adults completely lost their sensitivity to photoperiod after bilateral removal of their compound eyes. Unilateral removal of the compound eye also affected the crickets under a short-day photoperiod, and the incidence of diapause eggs was intermediate between that laid by intact adults and that laid by adults after the bilateral removal of compound eyes. The incidence of diapause eggs in sham-operated crickets was not significantly different from that in intact crickets under both sets of photoperiodic conditions. These results show that P. nigrofasciatus perceives the photoperiod through its compound eyes.     

Effect of maximal arm exercise on skin blood flux in the paralyzed lower limbs in persons with spinal cord injury

The purpose of the present study was to examine the effect of maximal arm exercise on the skin blood circulation of the paralyzed lower limbs in persons with spinal cord injury (PSCI). Eight male PSCI with complete lesions located between T3 and L1 performed graded maximal arm-cranking exercise (MACE) to exhaustion. The skin blood flux at the thigh (SBFT) and that at the calf (SBFC) were monitored using laser-Doppler flowmeter at rest and for 15 s immediately after the MACE. The subject's mean peak oxygen uptake and peak heart rate was 1.41 ± 0.22 1·min⁻¹ and 171.6 ± 19.2 beats·min⁻¹, respectively. No PSCI showed any increase in either SBFT or SBFC after the MACE, when compared with the values at rest. These results suggest that the blood circulation of the skin in the paralyzed lower limbs in PSCI is unaffected by the MACE.     

Human T Cell Leukemia Virus Type 1 (HTLV-1) Antibodies in Healthy Populations and Renal Transplanted Patients in the North-East of Brazil

The seroprevalence of human T cell leukemia virus type 1 (HTLV-1) infection was investigated in Brazilians (570): native inhabitants (298) and descendants from Japanese (272) living in Recife and its neighborhoods—North-east of Brazil. Furthermore, polytransfused renal transplanted patients (54) were also examined for the serological status to this virus. The seropositivity to HTLV-1, screened by enzyme-linked immunosorbent assay (ELISA), was low: 1.34% for the local population and 0.73% for the descendants from Japanese. However, the seropositivity for the renal transplanted patients was found to be 11.1%. This higher value suggests that this retrovirus infection seems to be of importance in this clinical condition.     

Production and composition of extracellular polysaccharide from cell suspension cultures of Mentha

A suspension culture of Mentha was established from callus which formed on the tips of young shoots of a Mentha hybrid (M. arvenis × M. spicata). Changes in growth parameters during a culture cycle were recorded. The general appearance of cells during division and growth, including the changes in cell form, was also represented.Suspension-cultured cells of Mentha hybrid released a large amount of extracellular polysaccharides (ECP) mainly at the logarithmic phase of the growth cycle. The ECP contained galacturonic acid as major components and arabinose, galactose, glucose, xylose, rhamnose and mannose as minor components. The ratio of the uronic acid content to total sugar content in the ECP was below 40% at day 7, but increased up to 90% at day 21. The relative contents of xylose and glucose in the ECP decreased during the culture period, while the arabinose content increased and those of rhamnose, mannose and galactose remained constant.The IR spectrum suggested that the ECP were low-methoxylated pectic polysaccharides. The presence of lignin and related compounds in the ECP was not detected. The protein content of the ECP was about 10% and the main amino acids were alanine, proline, hydroxyproline, valine, asparticacid and serine, in that order.     

Effects of stereochemical structures of tetrahydrobiopterin on tyrosine hydroxylase.

1. Four stereochemical isomers of tetrahydrobiopterin, i.e., 6-L-erythro-, 6-D-erythro-, 6-L-threo-, or 6-D-threo-1,2-dihydroxypropyltetrahydropterin, have been synthesized and used as cofactors for tyrosine hydroxylase (EC 1.14.18.-) purified from the soluble fraction of bovine adrenal medulla. The L-erythro- (the putative natural cofactor) and D-threo isomers showed a striking similarity in their cofactor activities for tyrosine hydroxylase; the remaining two isomeric tetrahydrobiopterins, D-erythro and L-threo isomers, also had very similar cofactor characteristics. 2. The Km values of the L-erythro and D-threo isomers as cofactor were found to be dependent on their concentrations. When their concentrations were below 100 muM, the Km values of the L-erythro and D-threo isomers were fairly low (about 20 muM). However, the Km values were markedly higher (about 150 muM) at concentrations above 100 muM. The same kinetic behavior was also observed with the tetrahydrobiopterin prepared from a natural source (bullfrog). In contrast, the Km value of the L-threo or D-erythro isomer was found to be independent of the concentration and remained constant throughout the concentration examined. 3. The Km values of tyrosine did not show much difference (from 20 muM to 30 muM) with respect to the structure of the four isomeric cofactors. At high concentrations tyrosine inhibited the enzymatic reaction with any one of the four tetrahydrobiopterin cofactors. 4. Oxygen at high concentrations was also inhibitory with any one of the four stereochemical isomers as cofactor. Approximate Km values for oxygen with the tetrahydrobiopterins as cofactor were 1-5%. 5. In contrast to the four isomers of tetrahydrobiopterin, when 6-methyltetrahydropterin or 6,7-dimethyltetrahydropterin was used as cofactor tyrosine or oxygen did no inhibit the enzymatic reaction at high concentrations, and the Km values toward the pterin cofactor, tyrosine, and oxygen were significantly higher than the Km values with the tetrahydrobiopterins as cofactor.     

Direct atomization atomic absorption spectrometry for intact biological samples: application to trace metal analysis in silkworm eggs and their hatched worms.

Highly sensitive carbon rod atomic absorption for trace elements was observed by direct atomization of samples with no pretreatment for intact silkworm eggs, their hatched worms, or National Bureau of Standards biological samples (orchard leaves and bovine liver). Crucial temperatures for drying, ashing, and atomization processes were found to obtain accurate results. Results were consistent with those of activation analyses and of ordinary atomic absorption with wet ashing. The precision and dynamic range of this method were evaluated. The advantages and disadvantages of the present approach were critically discussed.     

Electrotransformation of Thiobacillus ferrooxidans with plasmids containing a mer determinant.

The mer operon from a strain of Thiobacillus ferrooxidans (C. Inoue, K. Sugawara, and T. Kusano, Mol. Microbiol. 5:2707-2718, 1991) consists of the regulatory gene merR and an operator-promoter region followed by merC and merA structural genes and differs from other known gram-negative mer operons. We have constructed four potential shuttle plasmids composed of a T. ferrooxidans-borne cryptic plasmid, a pUC18 plasmid, and the above-mentioned mer determinant as a selectable marker. Mercury ion-sensitive T. ferrooxidans strains were electroporated with constructed plasmids, and one strain, Y4-3 (of 30 independent strains tested), was found to have a transformation efficiency of 120 to 200 mercury-resistant colonies per microgram of plasmid DNA. This recipient strain was confirmed to be T. ferrooxidans by physiological, morphological, and chemotaxonomical data. The transformants carried a plasmid with no physical rearrangements through 25 passages under no selective pressure. Cell extracts showed mercury ion-dependent NADPH oxidation activity.     

A contractile ring and cortical changes found in the dividing Tetrahymena pyriformis

A contractile ring consisting mainly of microfilaments was found in the fission zone of dividing Tetrahymena pyriformis. Diameters of the microfilaments were widely distributed from 2.5 to 15 nm. Ring-associated structures such as lateral stripes, linkers and beads with siender tails were recognized. Lateral stripes arranged at regular intervals of about 84 nm on some parts of microfilament bundles were found in both tangential and transverse sections, suggesting that they correspond to bands fastening the contractile ring microfilaments. Linkers that connect individual lateral stripes to the epiplasmic layer were present. Beads or beads with slender tails were found to be arranged on some microfilaments.The results of the present paper also indicate that drastic morphological changes occur in the cortex of the fission zone, especially in the epiplasmic layer, accompanying contraction of the division furrow. The epiplasmic layer which was proved to be a compact filamentous network in this study has been known to exist at the periphery of cytoplasm in immediate contact with one of the cell surface membranes, the inner alveolar membrane; however, in the fission zone of the dividing ceil, it was frequently separated from the membrane and subsided into the cytoplasm. The subsided epiplasmic layer was then loosened and dispersed. The subsidence of the epipiasmic layer appears to be caused by the force generated by the contraction of the contractile ring and transmitted with the linkers to the epiplasmic layer. The changes observed in the epiplasmic layer are presumably indispensable for the rigid cortical layer contraction involved in cytokinesis of Tetrahymena.