Action cascade of an insect gonadotropin,testis ecdysiotropin,in male Lepidoptera

Summary

Testis sheaths from late last instar larvae and mid-developing pupae of Heliothis virescens and Lymantria dispar synthesize ecdysteroid in vitro. Gonadal ecdysteroid can stimulate the production of growth factors from the sheaths which, in turn, promote the growth and development of the genital tract. Ongoing basal synthesis is controlled by positive feedback to exogenous ecdysteroid; titers of this hormone approaching those of molting last instar larvae and developing pupae effect maximum synthesis. These findings suggest that circulating titers of ecdysteroid hormone promote gonadal ecdysteroidogenesis, and thus coordinate the actions of the gonads with metamorphic events in the whole animal. Synthesis of ecdysteroid by testes is initiated, however, by a brain neuropeptide, testis ecdysiotropin (TE). TE is a 21 amino acid peptide of molecular weight 2472 Da. TE boosts basal steroid synthesis by pupal testis sheaths as well. It acts primarily via G_i protein and second messengers diacyl glycerol and low calcium influx, resulting in stimulation of phosphokinase C. G_s protein and its resultant messenger, cyclic AMP, also play roles in activation and inhibition of ecdysteroidogenesis. The interplay of controlling systems probably serves to fine tune a system essential to gonadal development and function.     

AUTONOMY AND AUTHENTICITY OF ENHANCED PERSONALITY TRAITS

There is concern that the use of neuroenhancements to alter character traits undermines consumer's authenticity. But the meaning, scope and value of authenticity remain vague. However, the majority of contemporary autonomy accounts ground individual autonomy on a notion of authenticity. So if neuroenhancements diminish an agent's authenticity, they may undermine his autonomy. This paper clarifies the relation between autonomy, authenticity and possible threats by neuroenhancements. We present six neuroenhancement scenarios and analyse how autonomy accounts evaluate them. Some cases are considered differently by criminal courts; we demonstrate where academic autonomy theories and legal reasoning diverge and ascertain whether courts should reconsider their concept of autonomy. We argue that authenticity is not an appropriate condition for autonomy and that new enhancement technologies pose no unique threats to personal autonomy.     

Advantageous and Detrimental Effects of Osmotic Pre-Sowing Treatment on the Germination Performance of Agrostemma githago Seeds

Dormant and after-ripened seeds of Agrostemma githago (corn-cockle)were pretreated in polyethylene glycol 400 (PEG) solutions attemperatures which would have allowed germination if the seedshad been imbibed in water, viz. 4?C or 20?C for after-ripenedseeds, and 4?C for dormant seeds. Pretreated seeds germinatedfaster than untreated seeds. The maximum decrease of the T₅₀(time to 50% germination) was 66%. Furthermore, pretreated seedswere capable of germination at supra-optimal temperatures whichotherwise had inhibited germination completely (20?C for dormantseeds and 30?C for after-ripened seeds). The percentage germinationat a supra-optimal temperature was considerably higher whenthe seeds had been primed at a temperature at which they developedmore extension power. The advantageous effects of the osmotic pretreatment were lessthan might be expected when the osmoticum had inhibited onlycell elongation. This was largely, if not fully, due to a generaldetrimental effect of osmotic stress and not to a selectiveinhibition of the processes which occur during the pregerminativephase in preparation for growth. Thus, during priming seedscomplete all or almost all processes which occur in water-imbibedseeds prior to radicle emergence. Key words: Agroatemma githago, dormancy, germination, germination performance, osmotic stress, priming     

Proetida—a disorderly order of trilobites

Classification should at least to some extent show phylogenetic relationships. It is therefore reasonable to base any classification on a discussion of phylogeny and analysis of phylogenetically relevant features. Adaptational features likely to evolve many times must be sorted out in the discussion of relationships, but may be useful to describe the evolution inside phyletic lineages defined by other means. The Proetida, as defined by Fortey & Owens 1975, are taken as an example of a heterogeneous taxon based on purely morphological features. A phylogenetic approach to ontogenetical, morphological and functional criteria seems to indicate that the Proetida fall into at least three groups without close relationships.     

Spiders of the genera Pachygnatha,Dyschiriognatha and Glenognatha (Araneae,Tetragnathidae), with a revision of the Afrotropical species*

Pachygnatha kiwuana Strand, P. leleupi Lawrence, P. longipes Simon. P. mucronata Tullgren, P. palmqvisti Tullgren, P. ruanda Strand and Dyschiriognatha argyrostilba (O.-P. Cambridge, 1876) (junior synonym: D. atlantica Holm, 1969) are redescribed. Puchygnutha hexutrucheutu, P. zuppu, P. procincta, P. okuensis, P. utromurginata, P. jansseni, P., goedeli, P. opdmwrdiue and Glenognatha smilodon, all species collected during the Belgian Cameroon expeditions, arc described as new. A key for all Afrotropical species is presented.     

PALEOMERUS-MEROSTOME OR MEROSTOMOID

The relation between segmentation and length of the head tagma in some groups of arthropods is discussed and used for a tentative assignation of Paleomerus to Merostomoidea Størmer, 1944. The relationships between Strabopidae Gerhardt, 1932, and Paleomeridae are discussed. A new specimen of P. hamiltoni gives some idea of the exterior surface of the exoskeleton.     

Rhythmic pulses of haemolymph pressure associated with parturition and ovulation in the tsetse fly,Glossina morsitans

Abstract Expulsion of the tsetse larva from the uterus of the female is preceded by 1–2 h of rhythmic pulses of haemolymph pressure that can be detected using a barographic technique. At first baseline pressure is maintained and all pulses are positive in relation to baseline. Then, about 1 h before parturition, baseline pressure increases, pulse intensity increases, and the pulses become both positive and negative in relation to baseline. Each pulse correlates with ‘bobbing’ action of the female's proboscis, the only external indication of this internal activity. A single large pressure pulse is observed at parturition, and thereafter the pressure level returns to the original baseline and pulsing action ceases. Around the presumptive time of ovulation, 1–2 h after parturition, another series of pressure pulses is observed. The pulses are the likely consequence of coordinated waves of muscular contraction that are essential preparation for successful parturition and ovulation.