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A Hernandorena

Publications and source records attributed to A Hernandorena.

10 recordsLinked to original sources
PubMed1994

Arthropod model systems for studying complex biological processes in the space environment.

Three arthropod systems are discussed in relation to their complementary and potential use in Space Biology. In a next biosatellite flight, Drosophila melanogaster pre-adapted during several months to different g levels will be flown in an automatic device that separates parental from first and second generations. In the same flight, flies will be exposed to microgravity conditions in an automatic unit in which fly motility can be recorded. In the International Microgravity Laboratory-2, several groups of Drosophila embryos will be grown in Space and the motility of a male fly population will be video-recorded. In the Biopan, an ESA exobiology facility that can be flown attached to the exterior of a Russian biosatellite, Artemia dormant gastrulae will be exposed to the space environment in the exterior of the satellite under a normal atmosphere or in the void. Gastrulae will be separated in hit and non-hit populations. The developmental and aging response of these animals will be studied upon recovery. With these experiments we will be able to establish whether exposure to the space environment influences arthropod development and aging, and elaborate on some of the cellular mechanisms involved which should be tested in future experiments.

Aging↗
PubMed1994

Recent approaches in the analysis of weightlessness effects on arthropod development.

The concept of Biological Development refers to the extremely complex process by which every biological organism reproduces starting from a huge single cell, the fertilized egg. It includes all aspects of cellular and intercellular structure and function. In spite of many recent advances, especially at the molecular and genetical level, we are still far from fully understanding the details and mechanisms at work in developmental systems. It is even unclear what physical mechanisms are used by the different molecular components resulting in the emergence of these higher levels of organization. Newman and Comper, have extensively discussed the "generic" physical forces potentially involved in pattern formation, arguing that among others, gravitational effects could be involved in the production of cytoplasmic, tissue and extracellular matrix components rearrangements playing a role in morphogenesis. Although plagued with the problem of being a very weak force, specially at the tiny dimensions of cells, gravity is one of the "generic" physical forces that have been continuously operating on biological organisms during evolution. Few scientists would argue against the idea that at least in the early times of evolution, gravity could have been involved in shaping the spatial inhomogeneities behind the initial phases of development.

Animals↗
PubMed1993

Effect of diets containing adenosine, guanosine, inosine or xanthosine on the nucleotide content of Artemia. Influence of mycophenolic acid.

Artemia uses the stored diguanosine tetraphosphate as a source of adenine and guanine nucleotides during development from the encysted gastrula to the free swimming larva. Further development of the larvae depends on a dietary source of purine rings. We have investigated the growth of Artemia in axenic cultures supplemented with 0.6 mg ml-1 of adenosine, guanosine, inosine or xanthosine. The total protein and soluble nucleotide content of Artemia grown in the presence of adenosine, guanosine or inosine was very similar, around (2 A260 units and 500 mg protein) and (4 A260 units and 1000 mg protein) after 4 and 6 days of postlarval development, respectively. The nucleotide pattern of those extracts subjected to HPLC were almost identical, the major peaks corresponding to ATP, ADP and AMP. Other nucleotides, not well characterized, were also present in those extracts. Mycophenolic acid (10 micrograms ml-1) inhibited the growth of Artemia (as measured by their protein and soluble nucleotide content) in the presence of adenosine and inosine as the purine source, and had no appreciable effect in the presence of guanosine. A quantitative analysis of the chromatographic peaks obtained from Artemia grown in the presence of any of the three nucleosides +/- mycophenolic acid showed that the effect of the antibiotic on each one of the chromatographic peaks was very similar, suggesting that Artemia, and probably other organisms as well, tend to maintain a balance between all nucleotides and to adjust the overall level to the limiting step(s) in their rates of synthesis/interconversion. Xanthosine was not able to support the development of Artemia.

Adenosine↗
PubMed1976

[Metabolic adaptation to a fatty diet: growth and morphogenesis of Artemia salina (L)].

Dietary AMP deficiency induces the morphogenesis of supernumerary gonopodes on abdominal segements. The AMP concentration threshold inducing supernumerary gonopodes depends on the lecithin and albumin concentration of the diet. The AMP concentration threshold corresponding to maximal xanthine oxidase activity depends to the maximal rate of protein biosynthesis. The results suggest the existence of a relation between the developmental physiology of Artemia and AMP and lipid metabolisms, relation which would imply the activity of xanthine oxidase.

Adaptation, Physiological↗