Nucleic acids in mummified plant seeds: screening of twelve specimens by gel-electrophoresis,molecular hybridization and DNA cloning

Summary Twelve seed specimens of varying ages and from different archaeological sites were analyzed for the presence of polymerized DNA and RNA. Amongst the samples tested, one of Vitis vinifera from an archaeological site in Iran (2,000–3,000 B.C.) was found to be completely devoid of nucleic acids. Zea mais seeds of Precolumbial age from Peru (about 800 A.D.) contained depolymerized DNA and RNA. Samples of Vitis vinifera and Rubus sp. from a Lombard archaeological site (800 A.D.) as well as radiocarbon dated seeds from the site of the Spring Sanctuary near Metaponto (I–IV century B.C.) were found to contain polymerized DNA and rRNA bands. However the electrophoretic properties of the rRNAs in one case and hybridization experiments performed with cloned seed DNA in the other, clearly demonstrated that the polymerized nucleic acids were not of plant origin.     

Detoxification of ochratoxin A,a food contaminant: Prevention of growth of Aspergillus ochraceus and its production of ochratoxin A

The toxicity of ochratoxin A (OTA), a mycotoxin produced by fungi ofAspergillus orPenicillium genera is now well documented. Its nephrotoxicity, immunosuppression, teratogenicity, and carcinogenicity have been widely studied. Physical and biochemical methods have been studied to prevent these toxinogenicAspergillus andPenicillium from producing OTA, and/or to destroy the mycotoxin when already produced in a liquid or a solid medium. Repeated freezing at ? 20?C and thawing at + 26?C aleatory reduce OTA production in a liquid medium. Exposure to UV B for different periods of time is efficient in preventing OTA production in a liquid medium. Gamma-irradiation from 2 to 5 kGy gives good results in preventing the production of OTA or destroying it when already produced. Carboxypeptidase is very efficient at 5 units/50 ml in a liquid medium for cleaving the OTA already produced.     

Freeze-preservation of rice cells: A physiological study of freeze-thawed cells

Rice ( Oryza sativa L.) cells returning to in vitro culture after preservation at superlow temperature in liquid nitrogen are characterized by a number of physiological alterations. These include: reduction in respiration and glucose uptake, loss of intracellular potassium, decrease in the cellular level of key metabolites (ATP, glucose-6-phosphate and pyruvate) and fragility of protoplasts following the action of cell wall-degrading enzymes.
Nevertheless, cell growth resumes after a short lag phase (2–4 days) with an actual 70–100% cell survival, thus indicating that the observed damage is not lethal and can be repaired in a short time.     

Alternative risk-taking styles: The case of time-budgeting strategies of terrestrial gastropods

The terrestrial slugs Arion ater, Limax maximus and Ariolimax columbianus have similar morphological designs but differ remarkably in their life history tactics and behavioural time budgets. The adaptive value of particular risk-taking styles was investigated using a comprehensive computer simulation model. The model allowed each species' success (growth rates, food acquisition) and costs (distance travelled, hydration deficits, injury from aggressive encounters) to be evaluated in various types of weather (benign, harsh and surprise). This was interpreted in terms of the species' life history design. In addition, each species was simulated with the behavioural strategy of the other two species substituted for its natural programming. The simulation experiments demonstrated how variations in a few simple rules could lead to divergent cost-benefit consequences. The model also illustrated that coarsely-tuned sensitivity to the environment may be better than finely-tuned responses, depending on the animal's ability to respond quickly and the degree of risk. The simulations suggested that competition has shaped the time-budgeting tactics of A. ater and L. maximus. Each species actually performed better in harsh weather, using the behavioural program of the other. L. maximus is an aggressive species with a narrow, nocturnal activity period. The concentrated activity of L. maximus may allow it to displace competitors more effectively, whereas the broader time span of A. ater's activity may be necessary to avoid L. maximus.     

Nucleic acids in mummified plant seeds: biochemistry and molecular genetics of pre-Columbian maize.

Nucleic acids fractions were isolated from pre-Columbian maize seeds and characterized using different approaches such as polyacrylamide gel electrophoresis, anti-DNA antibody binding, HPLC fractionation, molecular hybridization with cloned genes, and DNA amplification by the polymerase chain reaction. The nucleic acids were found to be very depolymerized (less than or equal to 140 base pairs in length) and composed mainly of ribosomal RNA. Despite the very low amount and degree of polymerization of seed DNA, specific maize nuclear Mu1, Mu4, Mu8 and, possibly, Mu5 element components could be detected, thanks to the use of amplification systems as short as 90 bp. The results suggest that evaluation of the relative proportions of Mu-type element components and, possibly, other maize genomic components in single mummified kernels, may offer a new key to the study of ancient maize populations.     

The regulation of activity in populations of the terrestrial slugLimax maximus (Gastropoda; Limacidae)

The activity of the slug Limax maximus was studied in relation to weather. Three hundred-and-fifty-eight hourly observations of activity and weather were made on 21 nights from May until October, 1976. Factors causally important to molluscan activity were included in a step-down correlation-regression analysis of daily and seasonal behavior. The analysis was also performed using weather data from the previous hourly observation. Models using lag-weather did not explain as much variability as did concurrent weather. The regression models explained about 73% to 87% of the observed variation in activity. The most important factors included in the regression models were time of day (circadian rhythm), light intensity, changes in light intensity and surface temperature. Shelter temperature, temperature gradients, length of the night, and time of sunset were also included in some models. Age and hydration were shown to be key factors in other experiments. A model incorporating weather thresholds estimated from field data explained 83.06% of the variability in the activity of L. maximus over the season. The values predicted from the model did not differ significantly from those actually observed in the field (Kolmogorov-Smirnov test, p>0.50).     

The role of fish-poultry integration on fish growth performance,yields and economic benefits among smallholder farmers in sub-Saharan Africa,Tanzania

Aquaculture practices from sub-Saharan Africa are characterised by low production, owing to improper technology. Production can be increased through integrating fish farming with other existing on-farm activities, particularly livestock husbandry. We assessed the role of fish-poultry integration on all male Nile tilapia, Oreochromis niloticus growth performance, yields and economic benefits among smallholder farmers in sub-Saharan Africa, Tanzania. The study also compared phytoplankton species composition, abundance and biomass between the fish-poultry integration and non-integrated system. After 180 days of the experiment, all male O. niloticus cultured under fish-poultry integration exhibited significantly higher growth rates than those in the non-integrated system (p < 0.05). Gross fish yield (GFY), net fish yield (NFY) and net annual yields (NAY) obtained from fish-poultry integration were significantly higher than those from non-integrated system (p < 0.05). Partial enterprise budget analysis revealed that fish-poultry integration was more profitable than the non-integrated system. Moreover, fish-poultry integrated system produced significantly higher phytoplankton abundance and biomass than those from the non-integrated system. Results demonstrate that rural smallholder farmers can achieve higher growth rate, farm net yields and income by integrating all male O. niloticus with other on-farm activities than practising a stand-alone fish culture system.     

Growth negatively impacts the life span of mammals

A negative intraspecific relationship between growth and longevity was proposed in the early 20th century. Indeed, stunting the growth of rodents by restricting their food dramatically extended life span. Subsequently, however, the hypothesis that growth exacerbates aging rates fell into disfavor. Contributing to this was (a) the establishment of a positive relationship between body size and longevity interspecifically, (b) purported antiaging impacts of growth hormone, and (c) the fact that the longevity of even mature rodents that had completed growth was extended by dietary restriction. Furthermore, intraspecific analytical studies failed to provide any clear resolution. This article presents the first global analyses of maximal longevity versus maximum mature mass for laboratory rats and mice, based on a relatively comprehensive compilation of research across the 20th century. Peak body mass (which reflects juvenile growth rates) was negatively associated with longevity within both species. Proximal mechanisms for impacts of growth on longevity appear congruent with the free radical and immunological theories of aging.     

Analysis of bacterial DNA in skin and muscle of the Tyrolean iceman offers new insight into the mummification process

About 80 sequences (16s ribosomal RNA gene) of bacterial DNA in samples of skin and muscle taken directly from the Tyrolean iceman (3350-3100 years B.C.) or recovered during the 1992 archaeological expedition at the Alpine site were analyzed to obtain clues to the natural mummification process that allowed the corpse of the Neolithic shepherd/hunter to be preserved for more than 5,000 years. The investigation was made more complex by the fact that the surface of the mummy had been swabbed with phenol soon after the discovery (September 19, 1991). Our results show that no trace of microbial DNA is left on the actual surface of the body, while the untreated skin still bears the remains of large numbers of bacteria belonging to the genera Sphingomonas, Afipia, Curtobacterium, Microbacterium, Agromyces, and others. Compared to the untreated skin, the iceman's muscle is also very rich in bacterial DNA. However, this DNA comes, with few exceptions, from the species Clostridium algidicarnis. The sharp difference in the bacterial DNA composition of skin and muscle suggests that the remains of the original cadaveric microflora of the latter have not disappeared during the iceman's taphonomic history. On the other hand, the massive presence of C. algidicarnis, a cold-adapted sporigenous, the DNA of which was previously (Ubaldi et al. [1998] Am. J. Phys. Anthropol. 107:285-295) found in the soft tissue of a naturally desiccated Andean mummy, indicates that the hypothesis that the iceman's corpse underwent rapid dehydration by the effect of a warm wind (f?hn) is no longer plausible. The results best fit with the hypothesis (Bereuter et al. [1997] Chem. Eur. J. 7:1032-1038) that the body was first covered by snow and ice, and then underwent thawing and, finally, desiccation.