Changes Induced by Salinity to the Anatomy and Morphology of Excised Pea Roots in Culture

Ann. Bot. 57, 811–818, 1986     

A Juvenile Hormone analogue enhances homosexual behaviour in female‐deprived males of the migratory locust

In laboratory colonies of crowded migratory locusts Locusta migratoria (L.), homosexual behaviour (i.e. males mounting other males) is commonly observed. Female‐deprived males of Locusta migratoria migratorioides R. & F. mount each other in a characteristic mating position, often forming a group of several insects. When allatectomized males are placed together with intact, female‐deprived males, the former are usually mounted by the latter, demonstrating some degree of control involving the corpora allata over homosexual behaviour. This may be related to the positive effects of Juvenile Hormone (JH) or Juvenile Hormone analogues (JHAs) in enhancing male sexual behaviour, as is shown in some other insects. In the present study, a potent JHA (i.e. pyriproxyfen) is injected into a group of young, crowded L. m. migratorioides males, and an equivalent group of control males is maintained in a separate cage. Both groups are deprived of females. Three times a week, during 2‐h observation periods, JHA‐injected and control males are placed together in the absence of females, and homosexual mountings, per group and per individual, are recorded every 10 min. Observations are performed for 10 weeks. Analysis of these data, including the time spent in mounting behaviour, the percentage of individuals within a group involved in the behaviour during the observation periods and the identity of both partners, reveals that the JHA‐treated males show a more intense homosexual mating behaviour than control males in all quantified parameters. This is the first report of the enhancement of homosexual behaviour by an endocrine factor in insects.     

The Andean Hapalopsittaca parrots (Psittacidae,Aves): an example of montane‐tropical lowland vicariance

Quintero, E., Ribas, C. C. & Cracraft, J. (2012). The Andean Hapalopsittaca parrots (Psittacidae, Aves): an example of montane‐tropical lowland vicariance. —Zoologica Scripta, 42, 28–43. We describe a phylogenetic and biogeographical pattern connecting high montane biotas to those of the lowlands, as exemplified by the exclusively montane parrot genus Hapalopsittaca and its lowland sister genus Pyrilia, both nested within Tavares et al.’s “amazons and allies” clade. As Hapalopsittaca is the only genus within the “amazons and allies” clade that is exclusively distributed in the Andes, the optimization leads to the inference that the ancestral distribution of the branch leading to Pyrilia + Hapalopsittaca was lowland. Museum specimens were examined to determine basal diagnosably distinct taxonomic units. Based on this analysis, mitochondrial sequences (cyt b and ND2 genes) from 17 individuals, mostly from toe pads, and representing all basal taxa within Hapalopsittaca, were obtained. A divergence‐dating analysis using both nuclear (RAG‐1) and mitochondrial (cyt b) genes was conducted to explore whether the uplift of the Andes coincides temporarily with the origin of this montane group, and thus might be causally linked to its origin. Molecular dating estimates the split between Hapalopsittaca and Pyrilia to have occurred between 6.6 and 8.0 Myr; thus, the timing of this highland/lowland disjunction is consistent with that of the final uplift of the Central Andes, supporting a hypothesis of vicariance due to Andean uplift. These results suggest that the taxonomic assembly of montane biotas may be, at least in part, explained by events of Earth history rather than by long‐distance dispersal and colonization. Diversification within Hapalopsittaca and the origin of current species are more recent in time and probably are related to Pleistocene climatic oscillations, as has been shown in other montane groups.     

Catechol Oxidase in Tissue 4

Catechol oxidase activity in tissue culture of apple fruit wasfollowed during growth. Enzyme activity was not found to becorrelated with the growth of the cultures. Cnltures with initiallyhigh enzyme activity show a lag in growth while enzyme activitydeclines. In cultures with an initial low activity, rapid growthis followed by an increase in enzyme activity which declinesagain as growth slows down. As the tissue ages, a greater proportionof enzyme activity is found in the soluble part of the cell. Low concentrations of O₂, lowered sucrose concentrations, orraised NaCl concentrations in the medium depress growth of theculture rapidly, while their effect on enzyme activity is delayed. Rapid desiccation of the tissue causes a large increase in enzymeactivity, possibly by activation, within 20 h. The subcollulardistribution of enzyme is changed at the same time.