A descriptive study of some Antarctic notaspidean opisthobranchs (Gastropoda), with description of a new genus and species

During the expedition “ANTARTIDA 9101”, organized by the Spanish Oceanographic Institute to the South Orkney Islands, four specimens of notaspidean gastropods were collected. Three of them have been identified as Bathyberthella antarctica Willan and Bertsch, 1987. However, one specimen, although externally similar to B. antarctica, had an internal anatomy exhibiting features that have enabled us to consider it to be a new genus and species. This new taxon is characterized by the presence of jaws without mandibular elements, and a vaginal gland that partially surrounds the distal region of the vaginal duct. In this paper the new genus and species is described. Additional anatomical data of the specimens of B. antarctica collected during the expedition are also included.     

Determination of ammonium and L-Glutamine in hybridoma cell cultures by sequential flow injection analysis

A flow injection anlytical system based on a gas diffusion membrane module for ammonia and an ammonium flow-through potentiometric detector has been set up for measurement of L-glutamine and ammonium ions in hybridoma cell cultures. The main feature of the system is that the same basic analytical concept and equipment is used in both measurements, the only difference being for the determination of L-glutamine, in which the sample flows through an immobilized glutaminase cartridge. The conditions to enable the performance of both analysis consecutively, avoiding potential interferences by unwanted deamination of other compounds in the samples, have been determined. Finally, the proposed system has been compared with reference analytical methods for batch hybridoma cell culture experiments.     

Use of recombinant interferon-α in Human Immunodeficiency Virus (HIV)-infected individuals

Rationale and objective Interferon alpha (IFN-) has anti-retroviral activity and is a possible HIV infection-limiting factor. The aim of this work is to prevent or delay disease progression in asymptomatic Human Immunodeficiency Virus (HIV) carriers.Design and interventions Recombinant IFN alpha-2b (3×10⁶ IU 3 times weekly) was compared. to no treatment (control) in a randomized trial. Endpoints were: (i) appearance of any CDC group IV symptoms and (ii) disease progression (which excluded shifts to group IVC2 or reversible IVA, or IVB). The trial lasted from October 1987 to February 1992.Setting The trial was performed at the Santiago de las Vegas sanatorium, a specialized institution for the care of HIV-infected and AIDS patients.Population Subjects were anti-HIV-1 seropositive, Western blot-confirmed, asymptomatic (CDC group II), or with generalized lymphadenopathies (CDC group III). The groups had 79 (control) and 71 (IFN) patients.Main results Long-term IFN- treatments significantly reduced the proportion of patients who shifted to any group IV (control: 46/79; IFN: 14/71;p<0.001) or developed AIDS (control: 27/79; IFN: 12/71;p<0.05). IFN also delayed progression to AIDS (95% confidence interval for 0.5 probability of progression) from 67–83 to 116–180 months after infection. The IFN group had significantly less opportunistic infections and non-infectious complications. CD4 cell count and hemoglobin decreased in the control but not in the IFN group. Fewer IFN-treated patients developed positive serum HIV antigen detection.Conclusion IFN alpha treatment during the early stages of infection seems to be beneficial to the patients.Abbreviations CI confidence interval - AIDS Acquired Immunodeficiency syndrome - HIV Human Immunodeficiency Virus - IFN Interferon - CDC Center for Disease Control (USA) - SD standard deviation     

Supercritical carbon dioxide extraction of hydrocarbons from the microalgaBotryococcus braunii

Samples of the microalgaBotryococcus braunii were submitted to supercritical fluid extraction with carbon dioxide at 40 °C and pressures of 12.5, 20.0 and 30.0 MPa. The extraction yield and the fraction of the hydrocarbons in the extracts both increased with pressure and at 30 MPa these compounds were obtained rapidly. This behaviour is associated with the localization of the hydrocarbons outside the cell wall. In the extracts, which are fluid, golden and limpid, chlorophyll and phospholipids were not detected.Author for correspondence     

High altitude tissue adaptation in Andean coots: capillarity,fibre area,fibre type and enzymatic activities of skeletal muscle

Capillarity, fibre types, fibre area and enzyme activities of different skeletal muscles (pectoralis, extensor digitorum longus), tibialis anterior, plantaris and the myocardium were compared in Andean coot (Fulica americana peruviana) native to high altitude (Junín, Perú, 4200 m) and the same species nesting at sea level. Numbers of capillaries per square millimeter were higher in all high-altitude muscles when compared with sea-level muscles (P<0.0001). Moreover, values for capillaries per fibre and capillaries in contact with each fibre were higher in digitorum and tibialis high-altitude muscles. Muscle fibres were classified as Type I, Type IIA or Type IIB on the basis of their myofibrillar ATPase pH lability. Pectoralis muscle of high-altitude and sea-level coots presented only fibres of Type IIA. In contrast, all the leg muscles studied showed a mosaic pattern of the three fibre types. Fibre areas were determined using a Leitz Texture Analysis System. Significant differences in fibre area were observed (P<0.01) between high-altitude and sea-level muscles. Mean muscle fibre diameters were also lower in the high-altitude group than in the sea-level group. The enzyme activities studied were hexokinase, lactate dehydrogenase, citrate synthase and 3-hydroxyacyl-CoA-dehydrogenase. The oxidative capacity, as reflected by citrate synthetase and hydroxyacyl-CoA-dehydrogenase activities, was greater for myocardial and pectoralis than for leg muscles. However, analysis of maximal enzyme activities showed that there were no significant differences between the glycolytic and oxidative enzyme activities of high-altitude and sea-level coots. These results suggest that in Andean coots genetically adapted to high altitude, changes in muscle capillarity and fibre size, in addition to high haemoglobin O₂ affinity and low haemoglobin concentration, are sufficient to allow adequate energy production without increases in enzymatic activities.Abbreviations BSA bovine serum albumin - C:F ratio Capillaries per fibre - CAF Capillaries in contact with each fibre - CD capillary density (mm^-2) - CS citrate synthetase - EDL muscularis digitorum longus - fra fraction reduction area - HA high altitude - HAD hydroxyacyl-CoA-dehydrogenase - HK hexokinase - LDH lactate dehydrogenase - P ₅₀ PO₂ at which hemoglobin is half saturated with O₂ - P _aO₂ arterial partial pressure of oxygen - PAS periodic acid-schiff - PEC muscularis pectoralis - PLA muscularis planaris - P _tO₂ mean tissue oxygen pressure - P _vO₂ mixed venous partial pressure of oxygen - SD standard deviation - SL sea level - TA muscularis tibialis anterior - TAS texture analysis system     

Encystation in Entamoeba invadens

Knowledge of the biology and pathogenesis of the human parasite Entamoeba histolytica has been limited by the lack of efficient procedures to induce axenic encystation in the laboratory. However, such methods have been developed for E. invadens, a reptilian parasite, for which encystation can be induced by mechanisms that are as yet poorly defined. This has allowed the analysis of some morphological, physiological and biochemical events that accompany differentiation into cysts. Elucidation of these changes will lead to a better understanding of the process and therefore to the possibility of controlling it. Here, Everardo López-Romero and Julio Cézar Villagómez-Castro emphasize the metabolism of cyst-wall polymers as a potential target to inhibit cyst formation with specific drugs that would be in principle, harmless to the host.     

Models of patch dynamics in tropical forests

Recent interest in the ecology and evolution of metapopulations and conservation of fragmented populations has stimulated the development of models that combine patch and population dynamics in tropical forests. One approach uses matrix models that are actual metapopulation or multi-regional demographic models. Another approach uses computer simulations to model forest succession based on the behavior of individual trees. We review applications of both types of models and suggest new combined modelling approaches.     

Magic angle spinning 13C-NMR spin-lattice relaxation study of the location and effects of α-tocopherol,ubiquinone-10 and ubiquinol-10 in unsonicated model membranes

-Tocopherol, ubiquinone-10 and ubiquinol-10 have been studied by high resolution magic angle samples spinning ¹³C-nuclear magnetic resonance in egg yolk phosphatidylcholine multilamellar vesicles model membranes in order to assess their location and the induced perturbations on this model system. -Tocopherol is placed in such a position that it is in close contact with the head group of the phospholipid and exposed to the solvent. In this position it significantly perturbs the phospholipid head group, the 5a-CH₃ and the 7a-CH₃ groups being the closest parts to the membrane surface. On the other hand, ubiquinol-10 perturbs the membrane surface more than ubiquinone-10, but neither compound significantly changed the phospholipid head group conformation.     

Expression of mutations and protein release by yeast conditional autolytic mutants in batch and continuous cultures

Thermosensitive mutant strains of Saccharomyces cerevisiae that fail to generate an osmotically stable cell wall when grown at a non-permissive temperature release their cell contents upon expression of the mutation. Therefore, they may represent an alternative for the production of homologous or heterologous protein preparations. In order to analyse the expression of two of these mutations, lyt2 and slt2, we grew the corresponding strains under precisely defined conditions in batch and continuous fermentors. A switch in the temperature of batch cultures from 24° C to 37° C determined lysis of the cells with a significant release of intracellular enzymes. These include alkaline phosphatase and periplasmic proteins such as glucan-degrading enzymes, the pattern of cell lysis and protein release being maintained for about 6 h. One-stage continuous cultures of a lyt2 mutant were maintained for long periods at 37° C; a fraction of the population lysed and released the indicated proteins, but eventually a revertant of the lytic phenotype was selected. To avoid this, a two-stage continuous culture system was developed by connecting two fermentors in series, the effluent from the first one at 24°C being fed to the second one adjusted to 37° C. A steady state of cell lysis and protein liberation was reached in the second-stage fermentor without any evidence of selection of revertants. This system can be very useful for developing conditions for the use of yeast strains to produce protein preparations. Correspondence to: C. Nombela     

A molecular marker-based linkage map of diploid bananas (Musa acuminata)

A partial molecular linkage map of the Musa acuminata diploid genome is presented. This map is based on 58 RFLP, four isozyme and 28 RAPD markers segregating in an F₂ population of 92 individuals. A total of 90 loci was detected, 77 of which were placed on 15 linkage groups while 13 segregated independently. Segregation distortions were shown by 36% of all loci, mostly favoring the male parent. Chromosome structural rearrangements were believed to be one of the main causes of these distortions. The use of genetic linkage data to further the genetic and evolutionary knowledge of the genus Musa, as well as to help improve the design of breeding strategies, is discussed.