Acridomorpha (Orthoptera) species associated with the protected wetlands of Santa Lucía, Montevideo, Uruguay

The diversity of Acridomorpha in protected areas of Uruguay has been little studied to date. In the protected wetlands of Humedales de Santa Lucía in the Montevideo Department, we made monthly surveys from December 2012 to March 2013. Sampling was conducted with entomological nets and by hand. We collected 1216 individuals of 26 dif-ferent species belonging to seven subfamilies. Gomphocerinae and Melanoplinae were the most abundant, accounting for 71% and 16% of the individuals respectively. The Shannon index showed a medium diversity, but the Berger-Parker dominance index and Pielou equitativity index indicate a slight dominance of the acridomorph community studied. This is probably because five species accounted for 87% of the individuals collected. Although our results are similar to previous studies of acridomorph communities in grasslands of the region, our study, the first of this kind for this ecosystem in Uruguay, will be important for the conservation of this protected area

Differential expression of voltage-activated calcium channels in III and XII motoneurones during development in the rat

To further our understanding of the role that voltage-activated Ca2+ channels play in the development, physiology and pathophysiology of motoneurones (MNs), we used whole-cell patch-clamp recording to compare voltage-activated Ca2+ currents in oculomotor (III) and hypoglossal (XII) MNs of neonatal [postnatal day (P)1-5] and juvenile (P14-19) rats. In contrast to III MNs that innervate extraocular muscles, XII MNs that innervate tongue muscles mature more rapidly, fire bursts of low frequency action potentials and are vulnerable to degeneration in amyotrophic lateral sclerosis. In neonates, low voltage-activated (LVA) Ca2+ current densities are similar in XII and III MNs but high voltage-activated (HVA) Ca2+ current densities are twofold higher in XII MNs. The HVA Ca2+ channel antagonists (nimodipine and nifedipine for L-type, omega-agatoxin-TK for P/Q-type and omega-conotoxin-GVIA for N-type) revealed that, while N- and P/Q-type HVA Ca2+ channels are present in both MN pools, a 3.5-fold greater P/Q-type Ca2+ current in XII MNs accounts for their greater HVA Ca2+ currents. Developmentally, LVA and HVA Ca2+ current densities decrease in III MNs but remain unchanged in XII MNs. Thus, the differences between these MN pools increase developmentally so that, in juveniles, the LVA Ca2+ current density is twofold greater and the HVA Ca2+ current density is threefold greater in XII compared with III MNs. We propose that this differential expression of LVA and HVA Ca2+ channels in XII and III MNs during development contributes to their distinct physiology and may also be a factor contributing to the greater susceptibility of XII MNs to degeneration as seen in amyotrophic lateral sclerosis.</p

P2 receptors modulate respiratory rhythm but do not contribute to central CO₂ sensitivity in vitro

Multiple brainstem sites are proposed to contribute to central respiratory chemosensitivity, however, the underlying molecular mechanisms remain unknown. P2X₂ subunit-containing ATP receptors, which mediate pH-sensitive currents, appear to contribute to central chemosensitivity in vivo [J. Physiol. 523 (2000) 441]. However, recent data from P2X₂ knockout mice [J. Neurosci. 23 (2003) 11315] indicate that they are not essential. To further explore the role of P2 receptors in central chemosensitivity, we examined the effects of P2 receptor agonists/antagonists on respiratory-related activity and CO₂-sensitivity of rhythmically-active in vitro preparations from neonatal rat. Our main findings: (i) that putative chemosensitive regions of the ventrolateral medulla are immunoreactive for the P2X₂ subunit; (ii) that ATP potentiates respiratory frequency in a dose-dependent, and PPADS-sensitive (P2 receptor antagonist), manner; and (iii) that the increase in burst frequency produced by increasing CO₂ is unaffected by PPADS, indicate that ATP is a potent modulator of respiratory activity, but that P2 receptors do not contribute to central chemosensitivity in vitro.16 page(s