Mitochondrial DNA evolution in the genus Equus

Employing mitochondrial DNA (mtDNA) restriction-endonuclease maps as the basis of comparison, we have investigated the evolutionary affinities of the seven species generally recognized as the genus Equus. Individual species' cleavage maps contained an average of 60 cleavage sites for 16 enzymes, of which 29 were invariant for all species. Based on an average divergence rate of 2%/Myr, the variation between species supports a divergence of extant lineages from a common ancestor approximately 3.9 Myr before the present. Comparisons of cleavage maps between Equus przewalskii (Mongolian wild horse) and E. caballus (domestic horse) yielded estimates of nucleotide sequence divergence ranging from 0.27% to 0.41%. This range was due to intraspecific variation, which was noted only for E. caballus. For pairwise comparisons within this family, estimates of sequence divergence ranged from 0% (E. hemionus onager vs. E. h. kulan) to 7.8% (E. przewalskii vs. E. h. onager). Trees constructed according to the parsimony principle, on the basis of 31 phylogenetically informative restriction sites, indicate that the three extant zebra species represent a monophyletic group with E. grevyi and E. burchelli antiquorum diverging most recently. The phylogenetic relationships of E. africanus and E. hemionus remain enigmatic on the basis of the mtDNA analysis, although a recent divergence is unsupported.      

Dissimilarity between prostaglandin E1 and nitric oxide donors as potentiators of plasma exudation in the rabbit skin in vivo

The ability of prostaglandin E₁ (PGE₁) and nitric oxide (NO) donor compounds such as sodium nitroprusside (SNP), glyceryl trinitrate (GTN), and 3-morpholino-sydnonimine (SIN-1) to modulate the histamine- and bradykinin-induced increase in microvascular permeability have been investigated in rabbit skin. The effect of the NO synthesis inhibitor N^ω-nitro- -arginine methyl ester ( -NAME) on the plasma exudation induced by histamine and bradykinin was also studied. Local edema formation was evaluated using [¹²⁵I]human serum albumin. New Zealand white rabbits received an intravenous injection of [¹²⁵I]human albumin followed immediately by the intradermal injection of edematogenic agents into the shaved dorsolateral skin. PGE₁ (0.1 nmol/site) significantly potentiated both histamine- and bradykinin-induced edema. In contrast, SNP (0.4–400 nmol/site), SIN-1 (0.4–400 nmol/site), and GTN (0.4–40 nmol/site) did not affect the edematogenic response induced by either histamine or bradykinin. GTN (0.4–40 nmol/site) also had no effect on the increase in plasma exudation induced by histamine and bradykinin in the presence of PGE₁. -NAME (50–400 nmol/site), but not its enantiomer -NAME, dose-dependently reduced the edema formation induced by a combination of either histamine or bradykinin with PGE₁. This inhibition was significantly reversed by SNP (4–400 nmol/site) and by high doses (2.5 μmol/site) of -arginine (but not by -arginine). Our results thus demonstrate that PGE₁, but not nitrovasodilators, can actually potentiate histamine- and bradykinin-induced edema in rabbit skin. This discrepancy cannot be explained by the lack of vasodilator activity of the nitrovasodilators since these were able to reverse the -NAME-induced inhibition of the edema provoked by histamine. Rather, this difference most likely reflects the ability of PGE₁ to modulate vascular permeability by mechanism(s) other than an increase in arterial flow.     

Beyond the green: assessing quarry restoration success through plant and beetle communities

In assessing the effectiveness of ecological restoration actions, outcomes evaluation using a multi‐taxa approach can greatly contribute to a clearer understanding of their success/failure. Since comprehensive biodiversity assessments are rarely possible, choosing taxa groups that are indicative of the ecosystem's structural and functional recovery is of major importance. Our goal was to evaluate the success of revegetation actions performed in a Mediterranean limestone quarry, using plants and epigean beetles as indicators. We compared their abundance, diversity, and community composition between revegetated sites aged 5, 13, and 19 years and a natural reference. Total plant cover significantly increased with restoration age and quickly reached reference values. However, native woody species cover dropped in the oldest site, while non‐native species became dominant. The abundance of beetles was always lower in restoration sites when compared to the reference, increasing with age, although not significantly. The richness of both plant species and beetle families was lower in restoration sites and did not show any trend towards the reference values. Finally, using nonmetric multidimensional scaling, the composition of plant and beetle communities from restoration sites showed a clear separation from the reference. Restoration efforts have successfully modified post‐quarry sites, but considerable differences remain, probably largely related to the use of the non‐native species Pinus halepensis in restoration plans. P. halepensis high cover in restoration sites greatly affects the structure of the ecosystem, and most likely its functioning too, as well as related ecosystem services, causing divergence from the reference values and compromising restoration success.