"Necking" behaviour in the giraffe

Previous references to "necking" behaviour, and the main features of the study area are briefly outlined.
"Necking" behaviour in giraffe takes place only in all male herds. When the animals are in a head to head posture the intensity is either high or low, but when animals take up a head to tail posture the actions are always of high intensity and appear to have greater sexual significance.
The significance of "necking" is discussed, and it is suggested that these ritualized actions form an important sexuo-social bonding mechanism whereby a hierarchy is created amongst the males, and movement between strictly bachelor and mixed herds helps to maintain contact between the sexes in this polygamous mammal.     

Linkage of PGK1 to X-linked severe combined immunodeficiency (IMD4) allows predictive testing in families with no surviving male

Summary We present a linkage map of DNA probes around the X-linked severe combined immunodeficiency (IMD4) locus at Xq11-13. DXS159 and PGK1 show no cross-overs with the disease locus (Lod 3.01 at = 0.00). The order of loci is DXS1-DXS106-(DXS159-PGK1-IMD4)-DXS72-DXYS1. Members of families whose carrier status has been established by X-inactivation patterns were included in the analysis. As the probe (pSPT/PGK), which is used for investigation of X-inactivation patterns, has been shown to be linked to the disease itself, it is possible to assign phase in mothers of sporadic cases who have been shown to be carriers, even when they have no surviving male offspring.     

Mimicry: Status of a classical evolutionary paradigm

Accounts of mimetic relationships reflect the traditional enthusiasm with which protective adaptations are described. However, our understanding of mimicry remains largely untested. Recent reviews of mimicry embrace many diverse phenomena, from tactics for defence and foraging, to pollination and mating. Selection for these mimetic phenomena is very different in each case and it is important to distinguish among categories of trophic, interspecific mimicry and sexually selected, nontrophic, intraspecific mimicry. Once categories are distinguished, the diversity of selection should clarify misunderstood concepts, such as the 'Batesian-Mallerian mimicry spectrum'. Experimental evidence of the selective value of mimicry is needed so that the advantages to mimics are clear when mimetic prey are confronted with real predator diversity. Such evidence should clarify the debate on how aposematism and mimicry evolve.     

Characterization of a Kinesin-Related Gene ATSV, within the Tuberous Sclerosis Locus (TSC1) Candidate Region on Chromosome 9Q34

In the search for candidate genes for the tuberous sclerosis (TSC1) disease locus on chromosome 9q34, we have isolated an overlapping series of 22 plasmid and phage cDNA clones covering nearly 7 kb and with an open reading frame of 5070 bp encoding a protein of 1690 amino acids. The putative protein product is a member of the kinesin superfamily and is homologous to the mouse KIF1A and theCaenorhabditas elegansunc-104 genes. Both KIF1A and unc-104 function in the anterograde axonal transport of synaptic vesicles. The human homolog is therefore termed H-ATSV (axonal transporter of synaptic vesicles, HGMW-approved nomenclature ATSV) Screening of DNA from 107 tuberous sclerosis patients and 80 unaffected individuals with H-ATSV cDNA probes by pulsed-field gel electrophoresis/Southern blotting following digestion by rare-cutting methylation-sensitive restriction enzymes showed variant banding patterns in three patients with tuberous sclerosis. However, further analysis indicated that these variant fragments represent a rare polymorphism probably associated with methylation of clustered restriction sites. There is no evidence to support H-ATSV as a candidate gene for TSC1.     

Extraction and genetic control of two new water-soluble proteins of mature barley seed

This paper describes the genetic control of two new water-soluble proteins in barley. Water-soluble proteins (WSPs) of mature barley seed form part of the albumin/globulin class of seed proteins. They can be extracted from hand-milled grain with water, though some WSPs are more efficiently extracted with a solution of 10 mM dithiothreitol. Polymorphisms for WSPs were detected in isoelectric focusing gels incorporating various ampholine combinations. Two new controlling genes (Wsp4 andWsp5) have been identified and located using wheat/barley chromosome addition lines and barley doubled haploids.Wsp4 is located on chromosome 2 (2H), andWsp5 was found to be tightly linked toWsp2 on the long arm of chromosome 7 (5HL). Segregation of a sixth gene (Wsp6) is also described, but this has not been mapped. The results are discussed with respect to other previously mappedWsp loci.This work was funed by the Scottish Office of Agriculture and Fisheries Department and the Agricultural and Food Research Council.     

The evolutionary origin of the 35 kb circular DNA of Plasmodium falciparum: new evidence supports a possible rhodophyte ancestry

In common with other Apicomplexan parasites, Plasmodium falciparum carries two extrachromosomal DNAs, one of which, the 6 kb element, is undoubtedly mitochondrial. The second, generally referred to as the 35 kb circle, is of unknown provenance, but the nature and organization of its genetic content makes a mitochondrial association unlikely and the molecule has features reminiscent of plastid genomes. We now report the occurrence on the circle of an open reading frame specifying a predicted 470 amino acid protein that shares more than 50% identity with a gene currently known only on the plastome of red algae. This high degree of conservation confirms the 35 kb circle's plastid ancestry, and we speculate that it may have originated from the rhodoplast of an ancient red algal endosymbiont in the progenitor of the Apicomplexa.     

Studies on plant regeneration from cotyledonary protoplasts in Brassica campestris

Protoplasts isolated from both 7-day-old light-grown and 4-day-old dark/dim light-grown cotyledons of four Brassica campestris varieties (Arlo, Sonja, Bunyip and Wonk Bok) were cultured in three liquid media: modified K8P, modified MS and modified Pelletier's B to compare the capacities for cell division and plant regeneration. Following cell wall regeneration the cultured protoplasts from dark/dim light-grown cotyledons of four varieties showed rapid division and high frequency of cell division compared with those isolated from light-grown cotyledons. The frequencies of cell division were significantly influenced by varieties and culture media but only in cultured protoplasts isolated from dark/dim light-grown cotyledons. The interaction between varieties and media was also significant. Cell colonies formed within 7–14 days in protoplast cultures from dark/dim light-grown cotyledons, and calli subsequently grown on a solid medium developed shoots when transferred onto a regeneration medium. Three of four tested varieties (Arlo, Sonja and Bunyip) showed shoot regeneration within 2–3 months after protoplast isolation, with a high degree of reproducibility in Arlo and Bunyip. Regenerated shoots, which were induced to root on half-strength MS medium with 0.1 mg.l^–1 IBA, survived in soil and grew to produce siliques and set viable seeds in the greenhouse. The present report is the first to document the production of regenerated plants that set seeds in Brassica campestris from cotyledonary protoplasts.Abbreviations BAP benzylaminopurine - CPW Composition of Protoplast Washing-solution - 2,4-D 2,4-dichlorophenoxyacetic acid - EDTA ethylenediamine-tetraacetic acid - GA₃ gibberellic acid - IBA indole-3-butyric acid - IAA indole-3-acetic acid - MS Murashige and Skoog medium - NAA -naphthaleneacetic acid - KT kinetin - FDA fluorescein diacetate - SDS sodium dodecyl sulfate     

The role of growth factors in gastrointestinal cell proliferation.

The epithelial lining of the gastrointestinal (GI) tract is in a state of continuous cell renewal, and the proliferating and differentiating/differentiated cell populations are spatially clearly demarcated. Members of the epidermal growth factor (EGF) family of peptides, the trefoil peptides and enteroglucagon appear to be the most important enterotrophic molecules for both normal cell renewal and healing after cell damage. Transforming growth factor-a (TGF-a) appears to be the primary physiological ligand for the EGF receptor (EGFR), promoting normal cell renewal, and TGF-a/EGFR are part of an autocrine loop in many intestinal cancers. In response to damage, a differentiating cell lineage arises from adjacent epithelium secreting EGF, TGF-a and trefoil peptides; this may be viewed as part of a ‘repair kit’ in damaged endodermally-derived tissue.