Evidence for a sensitizing pigment in the ocellar photoreceptors of the fly (Musca, Calliphora)

Summary A method is described that allows the spectral sensitivity of photoreceptors to be measured with high spectral resolution. It is shown that the sensitivity of the ocelli ofMusca andCalliphora has a vibrational fine structure in the ultraviolet, strongly indicative of a sensitizing pigment. The visual pigment has its absorption maximum close to 425 nm.     

Pygathrix nemaeus in Hainan? new evidence,no resolution

The douc, Pygathrix nemaeus, isnow restricted to the Indochinese Peninsula. An enigmatic report of this species in Hainan, China, is based on a specimen preserved in the Staatliches Museum für Tierkunde, Dresden. Examination of this specimen and relevant museum records reveals (a) that the specimen belongs to the subspecies P. nemaeus nemaeusand (b) that the specimen was received from the Dresden Zoological Garden, which apparently provided information that it originated in Hainan. Evaluation of the reliability of this geographic information is now impossible, because relevant zoo records no longer exist. The provenance of the problematic specimen — Hainan or Indochinese Peninsula-remains an open question.     

Cloning of the peacdc2 homologue by efficient immunological screening of PCR products

A homologue of the ubiquitous eukaryotic cell cycle regulatory gene,cdc2, has been cloned fromPisum sativum, the garden pea. A novel immunological strategy was devised and implemented for screening PCR products generated by degenerate oligonucleotide primers. We used PCR to construct a deletion derivative of anEscherichia coli expression plasmid carrying theSchizosaccharomyces pombe cdc2 gene. The deleted segment encoded the domain recognized by monoclonal antibody MAb-J4, a reagent which also detects a single protein in extracts of all plant species we have examined. PCR products, generated by appropriatecdc2 primers, were ligated into new restriction sites flanking the deletion, reconstituting the deleted epitope. This strategy, first validated on a cloned yeastcdc2 template as control, was applied to the highly efficient cloning of a cDNA segment comprising 60% of the peacdc2 homologue. DNA sequencing revealed strong amino acid sequence conservation among thecdc2 gene products from pea, yeast and animal cells. Genomic Southern analysis indicated that thecdc2 gene occurs as a single copy in pea. An additionalcdc2-like clone was recovered which displays amino acid sequence similarity with that of peacdc2. The reported cloning and screening strategy, though limited by the availability of appropriate immunological reagents, provides not only an efficient means of screening heterogeneous PCR products generated by degenerate probes and/or low stringency PCR, but also product verification by immunological criteria.