Absence of functional and structural homology of natural and recombinant human leukocyte interferon (IFN-α) with human α-ACTH and β-endorphin

A comparison of the amino acid sequence of one human recombinant IFN-α (IFLrA) with either human β-endorphin or ACTH reveals only a minimal and insignificant degree of homology. Also, synthetic ACTH, β-endorphin and β-endorphin-(1–15) have no antiviral protective effects on human fibroblasts and cannot inhibit the neutralization of the antiviral effects of natural IFN-α by an antiserum directed against the interferon. Anti ACTH and Anti β-endorphin do not neutralize the antiviral effects of IFLrA, and radioimmunoassays of partially purified natural IFN-α and pure IFLrA do not reveal any evidence of α-MSH or β-endorphin-like material in the interferons. These results demonstrate an absence of functional and structural homology of natural and recombinant IFN-α with ACTH and β-endorphin.     

PCR-based identification of individuals of Schistosoma japonicum representing different subpopulations using a genetic marker in mitochondrial DNA.

A mitochondrial NADH dehydrogenase I gene fragment (NDI) was sequenced for three laboratory maintained isolates of Schistosoma japonicum. Comparison of sequences representing the isolates (originally obtained from the Anhui and Zhejiang provinces of the People's Republic of China, and from the Philippines) revealed inter-isolate sequence variations of 0.2-0.6% and no intra-isolate variation was found. The sequences also indicated that while the amplification products of the Zhejiang and Philippine isolates contained a recognition site for the endonuclease RsaI, there was no such site in the Anhui isolate. This was tested by digesting amplification products from a number of individual worms with RsaI. Then an infection experiment was designed to test the value of this genetic marker for studies of the population biology of S. japonicum in the final host. For this, the two Chinese isolates were used. Three groups of mice (A-C) were exposed firstly to a primary infection and then challenge-infected at weeks 4 and 7 of the experiment. In group A the first infection was done with the Anhui isolate, and the two others with the Zhejiang isolate, thereby providing a specific, detectable cohort. In groups B and C the Anhui isolate was used for the second and third infection. All mice were perfused 5 weeks after the last challenge infection, and the NDI was subsequently amplified from DNA of the perfused worms and digested with RsaI. The digestion revealed that while infection groups A and B contained mixed populations of the Anhui and Zhejiang isolates, only Zhejiang worms were present in group C. We concluded that the absence/presence of the RsaI site in the NDI provides a useful marker for the delineation of cohorts of S. japonicum.     

Effects of temperature and salinity on the life history of the sailfin molly (Pisces: Poeciliidae): lipid storage and reproductive allocation

While the life history traits of animals usually exhibit substantial phenotypic plasticity, such plasticity might reflect either a simple alteration in the level of energy accrual and use or a genuine shift in energy allocation tactics between environmental conditions. The latter would represent genuine plasticity in the life history itself, and thus it is important to distinguish which of these two processes underlies the observed plasticity of life history traits. We investigated this issue by examining the effects of temperature and salinity variation during ontogeny on the allocation of biomass and lipid storage in male sailfin mollies, Poecilia latipinna. We raised males from four natural populations from birth to maturity in controlled laboratory conditions. Neither distinct temperatures (23 or 29°C) nor different salinity regimes (2, 12, or 20 parts per thousand) affected body mass, although males from different populations differed substantially in body mass. However, males raised at the higher temperature had a greater allocation of biomass to testis and a lower allocation to viscera mass. The amount of stored lipid was altered by temperature variation but the direction and magnitude of the effect varied substantially among males from the different populations. Salinity variation affected neither biomass allocation nor the level of lipid storage. These results indicate that male mollies possess a flexible developmental program with respect to temperature that canalizes body size and alters the allocation of biomass among competing demands for reproductive readiness and capacity for energy storage. Received: 25 November 1996 / Accepted: 1 December 1997     

Audit of admission to medical school: III--applicants' perceptions and proposals for change.

Applicants to St Mary''s Hospital Medical School were asked to comment freely on the process of selection. They were particularly concerned about the role of interviews, excessive emphasis on academic achievement, the problem of rank-ordering choices on the UCCA form, and possible biases in selection. These concerns and the results of our survey suggest that candidates should not be asked to rank their choices in order of preference, that UCCA applications for medicine should be subject to an early closing date, that as many applicants as possible should be interviewed, that applicants should be encouraged to apply after taking A levels, that educational opportunity should be taken into account in assessing A level grades, and that mature students should be encouraged, not least by providing mandatory awards for a second degree in medicine.