Planarian Immobilization,Partial Irradiation,and Tissue Transplantation

The planarian, a freshwater flatworm, has proven to be a powerful system for dissecting metazoan regeneration and stem cell biology^1,2. Planarian regeneration of any missing or damaged tissues is made possible by adult stem cells termed neoblasts³. Although these stem cells have been definitively shown to be pluripotent and singularly capable of reconstituting an entire animal⁴, the heterogeneity within the stem cell population and the dynamics of their cellular behaviors remain largely unresolved. Due to the large number and wide distribution of stem cells throughout the planarian body plan, advanced methods for manipulating subpopulations of stem cells for molecular and functional study in vivo are needed.Tissue transplantation and partial irradiation are two methods by which a subpopulation of planarian stem cells can be isolated for further study. Each technique has distinct advantages. Tissue transplantation allows for the introduction of stem cells, into a naïve host, that are either inherently genetically distinct or have been previously treated pharmacologically. Alternatively, partial irradiation allows for the isolation of stem cells within a host, juxtaposed to tissue devoid of stem cells, without the introduction of a wound or any breech in tissue integrity. Using these two methods, one can investigate the cell autonomous and non-autonomous factors that control stem cell functions, such as proliferation, differentiation, and migration.Both tissue transplantation^5,6 and partial irradiation⁷ have been used historically in defining many of the questions about planarian regeneration that remain under study today. However, these techniques have remained underused due to the laborious and inconsistent nature of previous methods. The protocols presented here represent a large step forward in decreasing the time and effort necessary to reproducibly generate large numbers of grafted or partially irradiated animals with efficacies approaching 100 percent. We cover the culture of large animals, immobilization, preparation for partial irradiation, tissue transplantation, and the optimization of animal recovery. Furthermore, the work described here demonstrates the first application of the partial irradiation method for use with the most widely studied planarian, Schmidtea mediterranea. Additionally, efficient tissue grafting in planaria opens the door for the functional testing of subpopulations of naïve or treated stem cells in repopulation assays, which has long been the gold-standard method of assaying adult stem cell potential in mammals⁸. Broad adoption of these techniques will no doubt lead to a better understanding of the cellular behaviors of adult stem cells during tissue homeostasis and regeneration.     

AI-2-dependent gene regulation in <Emphasis Type="Italic">Staphylococcus epidermidis</Emphasis>

Background  

Autoinducer 2 (AI-2), a widespread by-product of the LuxS-catalyzed S-ribosylhomocysteine cleavage reaction in the activated methyl cycle, has been suggested to serve as an intra- and interspecies signaling molecule, but in many bacteria AI-2 control of gene expression is not completely understood. Particularly, we have a lack of knowledge about AI-2 signaling in the important human pathogens Staphylococcus aureus and S. epidermidis.     

Investigation into the presence of and serological response to XMRV in CFS patients

The novel human gammaretrovirus xenotropic murine leukemia virus-related virus (XMRV), originally described in prostate cancer, has also been implicated in chronic fatigue syndrome (CFS). When later reports failed to confirm the link to CFS, they were often criticised for not using the conditions described in the original study. Here, we revisit our patient cohort to investigate the XMRV status in those patients by means of the original PCR protocol which linked the virus to CFS. In addition, sera from our CFS patients were assayed for the presence of xenotropic virus envelope protein, as well as a serological response to it. The results further strengthen our contention that there is no evidence for an association of XMRV with CFS, at least in the UK.     

Association kinetics with coupled diffusional flows: Special application to the lac repressor-operator system

The time development of the association of the lac repressor to the operator is considered in a model where the repressor is allowed to bind unspecifically to DNA and move along the DNA chain in a one-dimensional diffusion. The coupling to the three-dimensional diffusion outside the chain is introduced by letting the repressor associate and dissociate from the chain until it is finally bound to the operator. All distance correlations along the chain are included. The mean time of association is calculated and through a comparison with experimental data the molecular parameters are determined. The one-dimensional diffusion constant is found to lie of the order of 10^?9cm² s^?1. The model is sufficiently general to tie applicable to other similar systems.     

Further developments in the breeding population of lowland gorillas at Apenheul

In 1987 a second group of lowland gorillas was formed at Apenheul. Aspects of the zoo-technical management (diet, accommodation, etc.) are described. The management and the development of the population, including mother-rearing of all offspring, are described. Special attention is given to the formation of a second group by introducing two zoo-born females and a non-breeding female from one group to a nonrelated male to form a second group. These transfers of group members resulted rather quickly in pregnancies. The two groups are housed on adjacent islands, and the advantages and disadvantages of such a facility are discussed.     

Proposal for an integrated approach for the assessment of cross-media aspects relevant for the determination of “best available techniques” bat in the european union

The EC Directive concerning integrated pollution prevention and control (IPPC Directive 96/61/EC) obliges all Member States to make an integrated assessment of the impacts on the environment “as a whole”, as regards granting permission for and the operation of environmentally relevant industrial installations. The determination of “Best Available Techniques” BAT plays an essential role in the material transformation of the IPPC-Directive. An integrated approach for the assessment of cross-media aspects of techniques for the determination of BAT is outlined in this paper, which is grounded on the basic concept of Life Cycle Assessment (LCA), emphasising the need for decision support. The proposed assessment approach is applied to a case study sinter production in an integrated iron and steel works, which forms the base for several recommendations concerning further research.     

EFFECTS OF CULTIVAR AND PLANT AGE ON VEGETATIVE GROWTH OF THE STRAWBERRY,FRAGARIA ANANASSA

Growth of strawberry plants (Dunlap, Sparkle, and Catskill) in the greenhouse was affected by the time of rooting of the runners in the field. This was shown by more rapid leaf and leaf-area production, larger leaf size, more runners and root growth on the older compared to the younger runner plants. The oldest plants also produced the greatest number of flower buds, but the time of bloom was not appreciably affected. The growth responses of plants of different sizes were similar to those of plants of different ages. These growth responses were most apparent during the first stages of growth, but the resulting differences frequently persisted for several months. Significant differences between cultivars were also found. Initially the greatest leaf size and leaf area were produced by Catskill plants. Because of a higher leaf production rate, Sparkle plants eventually had the largest leaf area. Sparkle plants were the last to flower and also to initiate runner production. Dunlap plants were the first to flower and produced the largest number of flowers. In the field, leaf production records indicated responses from cultivars and plant age similar to those found in the greenhouse.     

The N-terminal amino-acid sequence of human placental sterylsulfatase

The N-terminus of the recently isolated sterylsulfatase of human placental cellular membranes was sequenced. According to our results, the enzyme preparation proved to be homogeneous at least with respect to this part of the polypeptide chain; the n-terminal sequence of the sulfatase previously proposed by others, however, had to be revised partially.