[Seasonal variation in mortality in the city of Valencia, Spain]. / Variación estacional de la mortalidad en la ciudad de Valencia, España.

OBJECTIVE: To study the seasonal variation in mortality for all causes, grouped according to age and sex, within the city of Valencia during the period 1976-1990 and its relationship with air temperature. MATERIAL AND METHODS: This is an ecological study using monthly global mortality and mean atmospheric temperature statistics for the city of Valencia, Spain between 1976 and 1990. The principal variable has turned out to be mortality for all causes. Mortality rates have been determined for specific age groups (0-4, 35-49, 50-64, 65-74 and > or = 75), as well as for both genders, within the city of Valencia for each of the 180-month period of investigation. Average monthly mortality data has been obtained and the percentage variation has been calculated. Graphical analysis has been used to examine the seasonal variation in mortality and in order to discern the nature of any relationship between atmospheric temperature and mortality. The regression line has been adjusted using the Loess method (smoothed regression motive, locally pondered). The association between mean temperature and mortality has calculated by means of multiple regression analysis controlling for trend, seasonality and period effect. RESULTS: A clear seasonal pattern emerges with mortality peaking during the Winter months and dipping during the Summer and early Autumn. The increase in mortality seen during the month of January came to 27.7% of the total mortality for females and 19.5% of the total mortality for males. By age groups, this increase was greater in the 75-plus age group. Graphically, the relationship between temperature and mortality has a V-shape appearance, with a lower mortality level when the mean daily temperature for the month in question is approximately 23 degrees Celsius. Based on this relationship, two complementary.

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.

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.

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.

Development of a new simplified nutritive medium for the axenic culture of Artemia.

A new artificial nutritive medium has been developed for the axenic culture of Artemia enabling the production of adults in less than 1 wk. The techniques for its preparation have been detailed. Its utilization is recommended for the standardized production of experimental animals.

[Metabolic adaptation to a fatty diet: growth and morphogenesis of Artemia salina (L)]. / Adaptation métabolique à un régime lipidique, croissance et morphogenèse chez 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.

EFFECTS OF TEMPERATURE ON THE NUTRITIONAL REQUIREMENTS OF ARTEMIA SALINA (L.).

1. The growth rate of Artemia in a uniform basic medium is faster at 30° C than at 25° C. 2. Temperature and salinity have opposite effects on the quantitative requirement for AMP. 3. At 30° C maximal growth is achieved with more AMP, more albumin, and less starch than at 25° C. 4. The effects of temperature are mediated by the ratio between energetic nutrients and AMP.