Record of Blue tilapia Oreochromis aureus (Steindachner, 1864) in the Eerste River catchment,Western Cape province,South Africa

Oreochromis aureus was imported from Israel into South Africa in 1959 but data on its current status in South Africa are lacking. Genomic DNA was extracted and the COI gene amplified at the South African Institute for Aquatic Biodiversity. The identity of the sequences and specimens was determined using the Barcode of Life Data Systems and GenBank. Morphological and genetic assessment demonstrated that 11 specimens collected from two farm dams in the Eerste River System, Western Cape province, were Oreochromis aureus. A MaxEnt model compiled using global distribution, rainfall and temperature data predicted that large areas of southern Africa were climatically suitable for this species, indicating considerable invasion debt in southern Africa. As a result, surveys to assess for the extent of the invasion in South Africa and eradication of existing populations, if feasible, are recommended management actions.     

Retrovirus purification: method that conserves envelope glycoprotein and maximizes infectivity.

A Sepharose 4B chromatographic method for purification of retroviruses is described which was less time consuming, increased purified virus yields, conserved viral glycoprotein, and increased recovery of biological infectivity in comparison with conventional sucrose gradient ultracentrifugation techniques.     

Incidents of rejection and indifference in Fu/HC incompatible protochordate colonies.

We test here for the existence of specific alloimmune memory in the rejection responses of the colonial tunicate Botryllus schlosseri. Colony specificity in these organisms is controlled by the Fu/HC locus. Rejection occurs only between colonies that do not share any allelic determinant at this locus. Two sets of experiments were conducted: 1) Forty-nine pairs of nonfusible oozooids were interacted naturally along a period of several months. They rejected, disconnected, and in 20% of the cases, interacted again. 2) Repeated colony allorecognition assays were done on 15 pairs of interacting subclones (up to 5 consecutive tests/pair). Major results indicate: 1) Not all ampulla-ampulla interactions resulted in necrotic areas, points of rejection (PORs). 2) A full repertoire of PORs was attained within the first 10 days. Thereafter, no more PORs were added. 3) The outcome of indifference (cases where ampulla-ampulla contacts did not result in rejection) was repeatedly recorded in multiple tests, and its frequency increased in the secondary and tertiary tests along a set of 5 consecutive tests. It is concluded that allospecific memory, as measured by an accelerated production of PORs and amplification in their number, was not characteristic of the Botryllus rejection phenomenon, which, however, reveals the qualities of a low responder. These results are discussed in the light of some aspects of tolerance in the mammalian system.     

Submaximal exercise in emphysema and malnutrition at two levels of carbohydrate and fat intake

Eight malnourished patients with emphysema (EMPH) and eight malnourished patients without evidence of lung disease (MLAN) received an infusion of 5% dextrose plus electrolytes (D5W) for 48 h and were then randomly assigned to a hypercaloric diet with either 53% of the calories as carbohydrate (CB) or with 55% as fat (FB) for the 1st wk, maintaining a constant protein intake. The alternate diet was given the following week. Ventilation and gas exchange were measured during supine cycle ergometry at 0, 12, and 25 W during the D5W, CB, and FB diet periods. At each exercise intensity, the EMPH group demonstrated a 12-15% greater O2 consumption, a lower respiratory quotient, and an O2 debt larger than that of the MALN group. Resting ventilation was higher during the CB than FB regimen in both groups of patients, but during the CB diet the EMPH group had a more exaggerated ventilatory response than the MALN group. The results demonstrate that EMPH patients have an unusual metabolic pattern during hypercaloric feeding and exercise. Furthermore in EMPH patients a FB regimen does not appear to create the additional stress on the respiratory system during exercise that is generated with a CB regimen.     

Mouse mammary tumor virus-related sequences in mouse lymphocytes are inducible by 12-O-tetradecanoyl phorbol-13-acetate

cDNA libraries from EL-4 cells treated with 12-O-tetradecanoyl phorbol-13-acetate (TPA) were screened for TPA-inducible sequences by differential hybridization. The most abundant inducible species was a sequence similar to that of mouse mammary tumor virus (MMTV). Induction of the mRNA corresponding to the MMTV-related sequences was already evident 30 min after TPA treatment, whereas the maximum accumulation occurred after 20 h of exposure to TPA. TPA also increased levels of MMTV-related RNA in the normal spleen cells of BALB/c and C57BL/6 mice. The level of RNA expression corresponding to MMTV-related sequences, however, was markedly elevated in EL-4 cells as compared with normal spleen cells. Southern blots of EL-4 cell DNA showed that the MMTV-related sequences were inserted into multiple locations of the EL-4 genome. Sequence analysis revealed that the MMTV-related cDNA clones included a part of the env gene and the right long terminal repeat of MMTV. However, the cDNA sequences were substantially different from published MMTV proviral sequences, most notably because of a contiguous deletion of 491 base pairs in the open reading frame within the U3 region.     

Construction of lambda gt103, a derivative of phage lambda gt10 that has unique EcoRI, NotI, SacI and SpeI sites and retains positive selection for recombinants.

A phage vector, lambda gt103, that has unique EcoRI, NotI, SacI and SpeI sites within the imm434 cI repressor gene, was constructed by PCR-aided site-directed mutagenesis of lambda gt10 [Huynh et al., DNA Cloning Techniques: A Practical Approach, 1985, pp. 49-78]. This vector allows directional cloning and retains positive selection for recombinants on Escherichia coli C600hfl strains (since only phages with disrupted cI genes plate on this host). Libraries made with this phage vector can be efficiently screened for clones in which a part of the insert is homologous to probe DNAs derived from a plasmid-based library, without cross-hybridization.