Advances in the systematics and evolution of western Mediterranean representative species of the Pentanema conyzae clade through genetic fingerprinting

Forty-five populations of Pentanema corresponding to seven species included in the Pentanema conyzae clade have been studied using AFLP fingerprinting. The results show that allopolyploidization could have been involved in the diversification of this group, specifically in species P. langeanum and P. maletii. Molecular data confirm the presence of P. britannicum in the Iberian Peninsula and key steps are provided to identify the species that are morphologically the most challenging.     

A modular approach to situation identification of the dynamics of bacterial populations synthesizing poly-β-hydroxybutyrate

Biotechnological processes involving bacteria are strongly nonlinear. Therefore, both their productivity and the final product quality may be considerably improved by applying appropriate control strategies to modulate behavior of the bacteria during transitional states. This requires advance identification of indicative signals by off-line investigation (i.e. experimental analysis) and on-line monitoring, (i.e. real time evaluation). A modular scheme is presented for doing this, which incorporates an Extended Kalman Filter and a prediction filter. If this is based on a suitable process-feature vector, which must be chosen in advance, the system can provide sufficient information to trigger appropriate feedback signals. Thus, it can provide a key element in modular situation control, allowing continuously periodic process management. In this publication the individual modules involved, and their assembly into an integrated system are described. Potential problems concerning selection of the feature vector, and experimental results are also discussed.     

Methyl-coenzyme M reductase of Methanobacterium thermoautotrophicum delta H catalyzes the reductive dechlorination of 1,2-dichloroethane to ethylene and chloroethane.

Reductive dechlorination of 1,2-dichloroethane (1,2-DCA) to ethylene and chloroethane (CA) by crude cell extracts of Methanobacterium thermoautotrophicum delta H with H2 as the electron donor was stimulated by Mg-ATP. The heterodisulfide of coenzyme M (CoM) and 7-mercaptoheptanoylthreonine phosphate together with Mg-ATP partially inhibited ethylene production but stimulated CA production compared Mg-ATP alone. The pH optimum for the dechlorination was 6.8 (at 60 degrees C). Michaelis-Menten kinetics for initial product formation rates with different 1,2-DCA concentrations indicated the enzymatic character of the dechlorination. Apparent Kms for 1,2-DCA of 89 and 119 microM and Vmaxs of 34 and 20 pmol/min/mg of protein were estimated for ethylene and CA production, respectively. 3-Bromopropanesulfonate, a specific inhibitor for methyl-CoM reductase, completely inhibited dechlorination of 1,2-DCA. Purified methyl-CoM reductase, together with flavin adenine dinucleotide and a crude component A fraction which reduced the nickel of factor F430 in methyl-CoM reductase, converted 1,2-DCA to ethylene and CA with H2 as the electron donor. In this system, methyl-CoM reductase was also able to transform its own inhibitor 2-bromoethanesulfonate to ethylene.     

Nitrogenase activity,hydrogen evolution and biomass production in different Casuarina symbioses

Nitrogenase activity, hydrogen evolution, biomass production and nodulation were studied in threeCasuarina species,C. equisetifolia Forst.,C. glauca Sieber ex Spreng andC. obesa Miq., either inoculated with a crushed nodule inoculum prepared fromC. glauca nodules or inoculated with the pure cultureHFP CcI3. Nodulation was also studied inC. cristata Miq. inoculated with the above mentionedFrankia sources. C. equisetifolia, C. glauca andC. obesa were nodulated when inoculated with both of theFrankia inoculum, whileC. cristata was very poorly nodulated. Nitrogenase activity per plant and on a nodule dry weight basis was significantly highest inC. glauca inoculated withC. glauca inoculum after 150 days from planting. This difference decreased and at 217 days from planting there was no significant difference between the symbioses, except forC. obesa inoculated withC. glauca inoculum which showed the significantly lowest nitrogenase activity. After 150 days from planting relative efficiency of nitrogenase was lowest inC. equisetifolia inoculated withHFP CcI3 and inC. equisetifolia inoculated withC. glauca inoculum. Biomass production was similar inC. glauca inoculated withC. glauca inoculum, inC. equisetifolia inoculated withHFP CcI3 and inC. obesa inoculated withHFP CcI3 at the final harvest. The data presented here show that there is a strong interrelationship between host plant and endobiont. This interrelationship is of considerable importance when introducing Casuarina symbioses for production of fuel wood.     

Block by phencyclidine of acetylcholine and barium induced adrenal catecholamine secretion

Activation of the sympathetic system by phencyclidine (PCP) should result in catecholamine release from the adrenals. However, adrenalectomy does not reduce PCP-induced hypertension. In an attempt to rectify this inconsistency, the direct effects of PCP on the bovine adrenal medulla were examined. At (3×10^?6M), PCP reduced the acetylcholine-(ACh)-induced catecholamine release by 50%. Surprisingly, barium-induced secretion of catecholamines was also reduced by PCP. ACh-induced catecholamine release was not altered by 10^?3M 4-aminopyridine (4 AP), the potassium channel blocker. Thus, calcium antagonist actions of PCP and consequent block of catecholamine secretion from adrenal medulla may explain the lack of effect of adrenalectomy on PCP-induced hypertension. Possible contributions of calcium and/or potassium channel blockade to other manifestations of PCP overdosage are discussed.     

The chemical-transformation products of 1,6-dibromo-1,6-dideoxygalactitol and 1,2:5,6-dianhydrogalactitol in aqueous solution

After hydrolysis of 1,6-dibromo-1,6-dideoxygalactitol (1) and 1,2:5,6-dianhydrogalactitol (2), 11 compounds were isolated, three of them as tritylated derivatives. Their structures were established on the basis of chemical evidence and, for four compounds, by X-ray diffraction. The main product of the hydrolysis of 1 was 3,6-anhydro-1-bromo-1-deoxy-dl-galactitol; the end-products of the hydrolysis of 2 were 1,5-anhydro-dl-galactitol, 2,5-anhydro-dl-altritol, and galactitol.     

Reproductive ecology and growth of a population of brown trout (Salmo trutta L.) in an aquifer-fed stream of Old Castile (Spain)

In the River Lobos-Ucero and its tributary the River Avión-Milanos (Duero basin, Old Castile, Central Spain), two limestone streams fed by aquifers, the population of brown trout, as compared with the populations of other European streams, shows a high growth rate, high condition coefficients, short life-span and early age at first maturity. Gonad cycle was also studied. Size distributions of unshed eggs exhibit a dynamic activity with a bi-modal distribution from June onwards, spawning occurred in the last days of November. Fecundity (F) can be predicted from trout length (L, mm) according to the equation: F= –646.47+5.6167 · L. Numbers and standing crop of trout range from 18 to 3903 ind. ha^–1 and 3.6 to 452.9 Kg ha^–1, reaching higher values in the sites close to the aquifers. Egg production had values of 22.4 and 18.0 eggs m^–2 in the Rivers Ucero and Avión-Milanos respectively. Some factors suggested as regulators of these demographical characteristics are discussed in the light of recent literature.     

Fourth-derivative spectrophotometry of proteins

Fourth-derivative spectrophotometry offers several advantages over classical absorption or difference spectrophotometry in examining the characteristics of aromatic amino acids in proteins. The basic principles of the technique and its applications are outlined.