Photosynthesis,Transpiration, and Water Use Efficiency of Vegetative and Reproductive Shoots of Grassland Species from North-Eastern China

The differences in net photosynthetic rate (P _N), transpiration rate (E), and water use efficiency (WUE) between the vegetative and reproductive shoots of three native grass species from the grassland of northeastern China [grey-green and yellow green populations of Leymus chinensis (Trin.) Tzvel., Puccinellia tenuiflora (Griseb) Scrib & Merr, Puccinellia chinampoensis Ohwi] were compared. The two type shoots experienced similar habitats, but differed in leaf life-span and leaf area. The leaf P _N and WUE for the vegetative shoots were significantly higher than those for the reproductive shoots in the grasses, while their E were remarked lower in the dry season. Relative lower leaf P _N and WUE for the reproductive shoots of grassland grasses may explain the facts of lower seed production and the subordinate role of seed in the grassland renewal in north-eastern China.     

Monoclonal antibodies to alpha-chain regions of human fibrinogen that participate in polymer formation

Monoclonal antibodies have been generated against a cross-link-containing derivative of alpha polymer (alpha XLCNBr), isolated following CNBr digestion of fibrin [Sobel, J. H., Ehrlich, P. H., Birken, S., Saffran, A. J., & Canfield, R. E. (1983) Biochemistry (preceding paper in this issue)]. One cloned cell line (F-102) was chosen for characterization based on its apparent specificity for the A alpha-chain region A alpha 518-584 (CNBr X). A second line (F-103) was selected because of its anti-A alpha 241-476 (CNBr VIII) properties. These two regions of the A alpha chain have previously been implicated as major contributors to the cross-linking process that leads to alpha-polymer formation. Radioimmunoassays have been developed, employing the immunoglobulins produced by clones F-102 and F-103. These assays have been applied, in conjunction with high-performance liquid chromatography purified tryptic and chymotryptic derivatives of CNBr VIII and CNBr X, to localize the respective determinants involved in antibody binding. In each case, virtually full immunoreactivity was exhibited by both the CNBr fragment and a single tryptic or chymotryptic peptide originating from it. These findings indicate that sequence-specific, rather than conformational, determinants were operative in the generation of antibodies F-102 and F-103. The epitope recognized by F-102 was localized to the region of A alpha 540-554, while the F-103 binding site resided within A alpha 259-276. When these radioimmunoassays were applied to study the relative immunoreactivity exhibited by a variety of fibrinogen derivatives, the results obtained support earlier suggestions that the COOH-terminal portion of the A alpha chain contains regions of random conformation.     

Towards an integrated system for bio-energy: hydrogen production by <Emphasis Type="Italic">Escherichia coli</Emphasis> and use of palladium-coated waste cells for electricity generation in a fuel cell

Escherichia coli strains MC4100 (parent) and a mutant strain derived from this (IC007) were evaluated for their ability to produce H₂ and organic acids (OAs) via fermentation. Following growth, each strain was coated with Pd(0) via bioreduction of Pd(II). Dried, sintered Pd-biomaterials (‘Bio-Pd’) were tested as anodes in a proton exchange membrane (PEM) fuel cell for their ability to generate electricity from H₂. Both strains produced hydrogen and OAs but ‘palladised’ cells of strain IC007 (Bio-Pd_IC007) produced ~threefold more power as compared to Bio-Pd_MC4100 (56 and 18 mW respectively). The power output used, for comparison, commercial Pd(0) powder and Bio-Pd made from Desulfovibrio desulfuricans, was ~100 mW. The implications of these findings for an integrated energy generating process are discussed.     

Presence of <Emphasis Type="Italic">C. albidus</Emphasis>, <Emphasis Type="Italic">C. laurentii</Emphasis> and <Emphasis Type="Italic">C. uniguttulatus</Emphasis> in Crop and Droppings of Pigeon Lofts (<Emphasis Type="Italic">Columba livia</Emphasis>)

Columba livia is an important reservoir and carrier of Cryptococcus neoformans, Cryptococcus uniguttulatus, Cryptococcus laurentii and Cryptococcus albidus. Upper digestive tract of this species is also known as a habitat for Cryptococcus neoformans. Given the increasing clinical interest of this microorganism, 331 swabs from crop and 174 dropping samples from pigeon lofts in Grand Canary Island have been studied. The obtained results show an extensive presence samples 81 positive (24.47%) of Cryptococcus spp. in analysed crops: 32 (9.66%) for C. neoformans, 24 (7.2%) for C. uniguttulatus, 23 (6.9%) for C. albidus and 2 (0.6%) for C. laurentii. In the same way, Cryptococcus spp was also isolated in 82 (47.13%), dropping samples: C. neoformans in 59 (33.9%), C. uniguttulatus, in 9 (5.17%), C. laurentii in 8 (4.59%) and C. albidus in 6 (3.44%) of the investigated samples, respectively. The cryptococcosis produced by species of cryptococci other than C. neoformans has become more important during the last decade, supporting the study on the role of pigeon in the epidemiology of this disease.     

Sequence heterogeneity and anomalous electrophoretic mobility of kinetoplast minicircle DNA from Leishmania tarentolae

Several unit-length minicircles from the kinetoplast DNA of Leishmania tarentolae were cloned into pBR322 and into M13 phage vectors. The complete nucleotide sequences of three different partially homologous minicircles were obtained. The molecules contained a region of approx. 80% sequence homology extending for 160–270 bp and a region unique to each minicircle. A 14-mer was found to be conserved in all kinetoplast minicircle sequences reported to date. The frequency distributions of various minicircle sequence classes in L. tarentolae were obtained by quantitative gel electrophoresis and by examination of the “T ladder” patterns of minicircles randomly cloned into M13 at several sites. By these methods we could assign approx. 50% of the total minicircle DNA into a minimum of five sequence classes. A sequence-dependent polyacrylamide gel migration abnormality was observed with several minicircle fragments both cloned and uncloned. The abnormality was dependent on the presence of a portion of the conserved region of the minicircle.     

The nuclear glutathione and its functions

During recent years the nuclear localization of glutathione has been confirmed and this fraction has been quantitatively determined. The nuclear GSH and the enzymes of its metabolism realize independent and important functions. They considerably differ from functions of hyaloplasmic and mitochondrial GSH. Glutathione interacts with regulatory pathways, involved into signal transmission into the nucleus.     

Specificity of sterol-glucosylating enzymes from Sinapis alba and Physarum polycephalum.

1. Sinapis alba L. seedlings contain glycosyltransferase catalyzing the synthesis of sterol glucosides in the presence of UDPglucose as sugar donor. The major activity occurs in the membranous fraction sedimenting at 300--9000 x g. Successive treatment of the particulate enzyme fraction with acetone and Triton X-100 affords a soluble glucosyltransferase preparation which can be partly purified by gel filtration on Sephadex G-150. Molecular weight of the glucosyltransferase is 1.4 . 10(5). Apparent Km values for UDPglucose and sitosterol are 8.0 . 10(-5) M and 5.0 . 10(-6) M, respectively. 2. Comparison was made of the S. alba glucosyltransferase with a similar sterol-glucosylating enzyme isolated from non-photosynthesizing organism Physarum polycephalum (Myxomycetes). UDPglucose was the most efficient glucose donor in both cases but the enzyme from Ph. polycephalum can also utilize CDPglucose and TDPglucose. Glucose acceptors are, in case of both enzymes, sterols containing a beta-OH group at C-3 and a planar ring system (5 alpha-H or double bond at C-5). The number and position of double bonds in the ring system and in the side chain, as well as the presence of additional alkyl groups in the side chain at C-24 are of secondary importance. 3. The present results indicate that both enzymes can be regarded as specific UDPglucose:sterol glucosyltransferases. Certain differences in their specificity towards donors and acceptors of the glucosyl moiety suggest, however, a different structure of the active sites in both enzymes.     

Inhalation of an Ethanol-Based Zileuton Formulation Provides a Reduction of Pulmonary Adenomas in the A/J Mouse Model

Potential efficacy of zileuton, a 5-LOX inhibitor, was evaluated for the reduction of pulmonary adenomas in the A/J murine model when administered via nose-only inhalation. Development of pulmonary adenomas was induced with benzo(a)pyrene. Animals were treated with a zileuton solution (5 mg/mL in 85:15 ethanol/water) either twice weekly or five times a week via nose-only inhalation; The placebo solution (85:15 EtOH/H₂O, no active) was also evaluated. Dose delivered was calculated to be 1.2 mg/kg per exposure for each zileuton group. After 20 weeks of treatment, surface tumors were enumerated and histologically assessed. A significant reduction in tumor count was noted for both the twice weekly administration (40%) and the five times a week administration (59%). The data also showed a significant reduction for the group, which received the placebo (approximately 58%). The treatment groups were also found to have an impact on the histological stages of adenoma development.     

Hypophysiotrophic thyrotropin releasing hormone (TRH) synthesizing neurons. Ultrastructure, adrenergic innervation and putative transmitter action

The neuropeptide thyrotropin releasing hormone (TRH) is capable of influencing both neuronal mechanisms in the brain and the activity of the pituitary-thyroid endocrine axis. By the use of immunocytochemical techniques, first the ultrastructural features of TRH-immunoreactive (IR) perikarya and neuronal processes were studied, and then the relationship between TRH-IR neuronal elements and dopamine-beta-hydroxylase (DBH) or phenylethanolamine-N-methyltransferase (PNMT)-IR catecholaminergic axons was analyzed in the parvocellular subnuclei of the hypothalamic paraventricular nucleus (PVN). In control animals, only TRH-IR axons were detected and some of them seemed to follow the contour of immunonegative neurons. Colchicine treatment resulted in the appearance of TRH-IR material in parvocellular neurons of the PVN. At the ultrastructural level, immunolabel was associated with rough endoplasmic reticulum, free ribosomes and neurosecretory granules. Non-labelled axons formed synaptic specializations with both dendrites and perikarya of the TRH-synthesizing neurons. TRH-IR axons located in the parvocellular units of the PVN exhibited numerous intensely labelled dense-core and fewer small electron lucent vesicles. These axons were frequently observed to terminate on parvocellular neurons, forming both bouton- and en passant-type connections. The simultaneous light microscopic localization of DBH or PNMT-IR axons and TRH-synthesizing neurons demonstrated that catecholaminergic fibers established contacts with the dendrites and cell bodies of TRH-IR neurons. Ultrastructural analysis revealed the formation of asymmetric axo-somatic and axo-dendritic synaptic specializations between PNMT-immunopositive, adrenergic axons and TRH-IR neurons in the periventricular and medial parvocellular subnuclei of the PVN. These morphological data indicate that the hypophysiotrophic, thyrotropin releasing hormone synthesizing neurons of the PVN are directly influenced by the central epinephrine system and that TRH may act as a neurotransmitter or neuromodulator upon other paraventricular neurons.     

Inactivation of microbial glutamin-(asparagin-)ase by azaserine and 6-diazo-5-oxo-L-norleucine

The effect of substrate analogues on glutamin-(asparagin-)ase from Pseudomonas aurantiaca-548 has been studied. The enzyme was demonstrated to be highly sensitive to the the action of 6-diazo-5-oxo-L-norleucine and azaserine. L-isomers of glutamine, aspartate, glutamate and several other substrate analogues with free alpha-amino groups protected the enzyme against the inhibitory DON effect. Thus, thorough preliminary selection of appropriate inhibitors, their dosage and treatment duration is needed for the recommendation of combined enzyme-inhibitor application in anti-tumour chemotherapy.