Cryobanking of viable biomaterials: implementation of new strategies for conservation purposes

Cryobanking, the freezing of biological specimens to maintain their integrity for a variety of anticipated and unanticipated uses, offers unique opportunities to advance the basic knowledge of biological systems and their evolution. Notably, cryobanking provides a crucial opportunity to support conservation efforts for endangered species. Historically, cryobanking has been developed mostly in response to human economic and medical needs — these needs must now be extended to biodiversity conservation. Reproduction technologies utilizing cryobanked gametes, embryos and somatic cells are already vital components of endangered species recovery efforts. Advances in modern biological research (e.g. stem cell research, genomics and proteomics) are already drawing heavily on cryobanked specimens, and future needs are anticipated to be immense. The challenges of developing and applying cryobanking for a broader diversity of species were addressed at an international conference held at Trier University (Germany) in June 2008. However, the magnitude of the potential benefits of cryobanking stood in stark contrast to the lack of substantial resources available for this area of strategic interest for biological science — and society at large. The meeting at Trier established a foundation for a strong global incentive to cryobank threatened species. The establishment of an Amphibian Ark cryobanking programme offers the first opportunity for global cooperation to achieve the cryobanking of the threatened species from an entire vertebrate class.     

A plethora of intercellular signals during Caenorhabditis elegans development

Reproducible cell-cell interactions contribute to the invariance of Caenorhabditis elegans development and allow high resolution study of molecular mechanisms of intercellular signaling. A number of new cell interactions have been discovered in the past year. The power of nematode molecular genetics has been increased through several technical advances and the genome project, and these new approaches are now being successfully applied both to familiar and new signaling mechanisms.     

Prediction of antigenic determinants and secondary structures of the major AIDS virus proteins

Criteria for the design of peptide vaccines to prevent AIDS are presented. The best vaccine candidates contain both B and T lymphocyte-defined epitopes in regions conserved in sequence between viral isolates. We propose that attention should focus on proteins specified by the gag and, possibly, pol genes in addition to the env gene envelope glycoproteins being actively studied. The predictions of B- and T-epitopes are refined by consideration of secondary structure prediction and inter-isolate sequence variability to suggest peptides from env, gag and pol that would be the best vaccine candidates.     

Characterization of the binding sites of c1 repressor of bacteriophage P1. Evidence for multiple asymmetric sites

The repressor of bacteriophage P1, encoded by the c1 gene, is responsible for maintaining a P1 prophage in the lysogenic state. In this paper we present: (1) the sequence of the rightmost 943 base-pairs of the P1 genetic map that includes the 5'-terminal 224 base-pairs of the c1 gene plus its upstream region; (2) the construction of a plasmid that directs the production of approximately 5% of the cell's protein as P1 repressor; (3) a deletion analysis that establishes the startpoint of P1 repressor translation; (4) filter binding experiments that demonstrate that P1 repressor binds to several regions upstream from the c1 gene; (5) DNase I footprint experiments that directly identify two of the P1 repressor binding sites. Sequences very similar to the identified binding sites occur in at least 11 sites in P1, in most cases near functions known, or likely, to be controlled by repressor. From these sites we have derived the consensus binding site sequence ATTGCTCTAATAAATTT. We suggest that, unlike other phage operators, the P1 repressor binding sites lack rotational symmetry.     

Fermentor cultivation of Thermoplasma acidophilum for the production of cell mass and of the main phospholipid fraction

The purpose of this work was to optimize the growth conditions for scale-up of mass production of the main phospholipid (MPL) fraction from the archaebacterium Thermoplasma acidophilum. T. acidophilum was cultivated in flasks in the presence of ³²P-ortho-phosphate under varying conditions. The lipids were extracted from the lyophilized cells and analysed by means of two-dimensional thin-layer chromatography. Autoradiography detected up to 11 different fractions. The monoglycosyl derivative of the MPL amounts to 60–80% and thus constitutes the main fraction of the total phospholipid. Variations in growth temperature, pH, yeast extract (YE), glucose and substitution of glucose by citrate were tested. The cells were examined by conventional and electron microscopy. During growth, the pO₂ decreased considerably, indicative of rapid O₂ consumption by the Thermoplasma cells. Growth under low O₂ tension, without addition of O₂, and under gassing with N₂ or CO₂ revealed that T. acidophilum is obligatorily aerobic. For large cell mass production the addition of YE was varied quantitatively and at time intervals. The apparently most economic procedure in the fermentors is: growth at 59°C and pH 2.0, with 10 g glucose/l and total amount of YE 6 g/l, applied in three portions, 2 g/l each, initially, after 18 and 24 h. Harvesting after 40 h yielded 0.66 g/l of cell dry mass. Scaling-up was successful from 1-l flasks to 10-l and 50-l fermentors under aeration of 0.02–0.04 vvm. Correspondence to: H.-J. Freisleben     

Modern microscopy in biofilm research: confocal microscopy and other approaches.

Microscopy is the only technique whereby bacterial biofilms can be studied at the single-cell level in situ. Our understanding of biofilm structure, physiology and control hinges on the application of confocal scanning laser microscopy and other advanced microscopic techniques. Gene expression in four dimensions (x,y,z,t), interspecies interactions, and the role of exopolymer are being defined.     

Observations on feeding, growth and electric discharge of newborn Torpedo ocellata (chondrichthyes, batoidei)

Newly born and neonate Torpedo ocellata were obtained from gravid females caught during the autumn off the Mediterranean coast of Israel. The young torpedos, which weighed about 11 g, were fed with live Blennius pavo Risso, and doubled their weight in about 4 months. The behaviour of the torpedo during feeding was examined and photographed. When attacking a fish, the torpedo emerges from being buried in the sand and assaults the approaching prey. First, the prey is trapped under the torpedo and then directed towards the ray's mouth by its body movements. Newborn and neonate torpedos are able to discharge their electric organ. The amplitude of the discharge of one day-old fish is approximately 4 V. It increases dramatically during the first three weeks of life to 20 V, reaching an asymptotic level of about 26 V, by the end of the fourth month.