Kin recognition in a subsocial treehopper (Hemiptera: Membracidae)

1. Insects exhibiting parental care usually can discriminate between kin and non‐kin individuals, allowing parents to avoid investment in foreign offspring. 2. This study investigated the occurrence of kin recognition in the sap‐feeding insect Alchisme grossa Fairmaire (Membracidae) through bioassays assessing median female distance to nymphs and degree of nymphal aggregation. Each bioassay involved groups consisting of a female and a cohort of kin or non‐kin nymphs (mother and non‐mother treatments, respectively). Furthermore, cuticular non‐volatile compounds were extracted from nymphal cohorts, analysed by gas chromatography‐mass spectrometry and compared between cohorts. 3. In both treatments, nymphs performed a ‘rocking behaviour’ which appears to be correlated with aggregation. Temporal patterns of degree of nymphal aggregation and median female–nymph distance differed between treatments, the former parameter being higher in the mother treatment and the latter being higher in the non‐mother treatment. 4. A total of 40 compounds were found in the extracts. The composition of cuticular non‐volatile compounds differed between nymphal cohorts. 5. These results support the notion that kin recognition in A. grossa is possibly mediated by nymphal rocking behaviour and/or cuticular non‐volatile compounds (i.e. visual and/or chemical cues).     

Molecular genetic variation in Passiflora alata (Passifloraceae), an invasive species in southern Brazil

A total of 85 wild plants were collected in different areas of southern and south-eastern Brazil, and studied for nrDNA internal transcribed spacers (ITS). Thirty-two of them were also investigated for two other nuclear ( G3pdh and LEAFY ), as well as eight plastid systems. Sixty-one ITS sequence types were identified, in a region of 412 bp, whereas 42 G3pdh haplotypes were found in a region of 1010 bp, and 23 LEAFY haplotypes in a region of 565 bp. GC content was higher in ITS (65%) than in the two other nuclear regions (40–42%), whereas nucleotide diversity was markedly higher in G3pdh than in the other two. No variability was found in the plastid systems. Most of the nuclear molecular diversity (56–86%) occurs at the intrapopulation level, and there is clear evidence of population expansion and little geographical structure. Historical information and field studies indicate that Passiflora alata is actively colonizing previously unoccupied areas in southern Brazil. High indices of intrapopulation variability were found in the region that is being colonized, similar to those found in areas where P. alata is native. Multiple introductions, as well the species' genetic structure and human interference, may explain these findings.  © 2006 The Linnean Society of London, Biological Journal of the Linnean Society , 2006, 88 , 611–630.     

Improved Tyrosinase Activity Stains in Polyacrylamide Electrophoresis Gels

Mammalian tyrosinase exists in a variety of subcellular locations and maturation states that result from a complex post-translational processing with possible regulatory implications. So far, SDS-PAGE has proven to be the method of choice for the resolution of tyrosinase isoforms. However, the relatively poor sensitivity of the currently available specific activity stain based on incubation of the gels with L-dopa until the formation of melanin has severely limited the use of electrophoresis in regulation studies. Two alternative staining procedures are presented and discussed. The first one involves the fluoro-graphic detection of radioactive melanin after incubation of the gels in the presence of L-[3-¹⁴C]-dopa. A similar method has already been used by others (Tsukamoto et al., 1992, Pigment Cell Res. [Suppl.] 2:84–89), but its performance has not yet been compared to the one of the dopa procedure. The sensitivity of this method can be varied by adjusting the isotopic dilution of the tracer and/or the time of exposure of the gel, but it is at least ten times higher than the one of the colorimetric stain. Moreover, the intensity of the bands is proportional to the initial tyrosinase activity over a wide range. Using this procedure, the activity present in the different subcellular fractions of melanocytes in culture can be easily detected. The second procedure involves the formation of a colored adduct between dopaquinone and MBTH. Its sensitivity is also more than one order of magnitude higher than the one obtained with L-dopa alone, and comparable to the one of the fluorographic method, but, as opposed to this latter, the complete staining can be performed in less than 1 hr.