Involvement of spectrin in the maintenance of phase-state asymmetry in the erythrocyte membrane

The fluorescent probe merocyanine 540 does not stain the plasma membrane of normal human or murine erythrocytes, nor of genetically abnormal human spherocytic erythrocytes. It does, however, stain erythrocyte membranes in several systems in which the underlying spectrin network is altered or missing. Because of the greater affinity of merocyanine 540 for fluid—phase lipid bilayers, these results suggest that the external leaflet of erythrocyte membranes becomes more disordered upon alteration or loss of the internal spectrin network. Analysis of the transbilayer arrangement of membrane phospholipids by digestion with phospholipase A2 suggests that lipid compositional asymmetry of the erythrocyte membrane is responsible for a phase-state asymmetry between the two lipid leaflets, and that spectrin is required to maintain this asymmetry and the gel-like state of the external leaflet.     

Polymorphism of transferrin and esterase in Alaskan wolves: evidence of close molecular homology with the dog

By the use of isoelectric focusing in polyacrylamide gels serum samples from 146 Alaskan wolves were studied with regard to transferrin (Tf) and esterase (ArE) polymorphism, comparing the phenotypic band patterns with those of selected Norwegian dogs. The study revealed Tf and ArE polymorphisms in the wolf with phenotypic band patterns being indistinguishable from the corresponding ones in dogs. This suggests the occurrence of the same two common Tf alleles in the wolf as in the dog. In the ArE system the results are consistent with the occurrence of three alleles which also occur in dogs whereas a fourth allele, so far not seen in dogs, is seen in Alaskan wolves.     

Sexual selection and genital allometry in the Hottentot golden mole (Amblysomus hottentotus)

Under sexual selection, genitalia typically undergo rapid and divergent evolution across species and competition between the sexes over control of fertilisation may drive the co-evolution of male and female sexual traits. Sexual selection can, therefore, influence genitalia in three fundamental but non-mutually exclusive ways: (1) cryptic female choice, (2) sperm competition and (3) sexual conflict. Golden moles (Chrysochloridae) are a highly specialised family endemic to sub-Saharan Africa. We examined intra-specific genital allometry of both male and female subterranean Hottentot golden moles (Amblysomus hottentotus). Consistent with previous studies in mammals, we found positive allometry and a high coefficient of variation (CV) for male genitalia. The results for female reproductive tract length of A. hottentotus contrast with the findings of previous studies as isometry was recorded. Based on the allometric relationships of both males and females presented here, we suggest that the males do not sequester females and that in the absence of visual cues the female may use penis size as an indicator of phenotypic quality.