Evolutionary species–area curves as revealed by single-island endemics: insights for the inter-provincial species–area relationship

The species–area relationship (SAR) between different biological provinces is one of the most interesting, but least explored aspects of the well-known species–area pattern. Following the usage that a biological province is a region whose species have for the most part evolved within it, rather than immigrating from somewhere else, we propose that islands can be considered equivalent to biological provinces for single island endemic species (SIEs). Hence, analyses of the relationships between numbers of SIEs and island area can be used as model systems to explore the form of inter-provincial SARs. We analyzed 13 different data sets derived from 11 sources, using the power (log–log) model. Eleven of the SIE–area relationships were statistically significant, explaining high proportions of the variance in SIE numbers (R² 0.57–0.95). The z-values (slopes) of the statistically significant SIE–area relationships ranged from 0.47 to 1.13, with a mean value of 0.80 (SD±0.24).
All the island systems in which SIE represent >50% of species exhibited z-values for the SARs of native species higher than those deemed typical of archipelagic SARs. The SIE–area slopes are quite similar to those previously calculated for inter-provincial SARs, indicating that, when speciation becomes the dominant process adding to the species richness of assemblages, high z-values should be anticipated, regardless of the biogeographical scale of the study system.     

Multimodal species abundance distributions: a deconstruction approach reveals the processes behind the pattern

It is becoming increasingly apparent that the species abundance distribution of many ecological communities contains multiple modes, a phenomenon that has been largely overlooked. Here, we test for multiple modes in the species abundance distribution using a combination of one, two and three mode Poisson lognormal distributions and an extensive arthropod dataset from the Azores. We consider the abundance distribution of twelve native laurisilva forest fragments and the combination of fragments within five islands, allowing us to detect whether patterns are consistent across scales. An information theoretic approach is employed to determine the best model in each case. To explore the processes driving multimodal abundance distributions we tested various potential mechanisms. We classified species as core if they are present in over half the fragments in our study, and as satellite if they are sampled in fewer than half the fragments. Furthermore, species are classified based on body size, whether they are indigenous (i.e. endemic or native non‐endemic) or introduced to the Azores, abundance in land uses other than native forest, and dispersal ability. We find that models incorporating multiple modes perform best for most fragments and islands. A large number of communities are bimodal, comprising a mode of very rare species and a mode of relatively common species. Deconstructing the full assemblages into their constituent subsets reveals that the combination of ecologically different groups of species into a single sample underpins the multimodal pattern. Specifically, the rarer mode prevailingly contains a higher proportion of satellite taxa, introduced species and species that are more adapted to anthropogenic land uses that surround the native forest.     

Healing of specialized tongue epithelium following cryosurgery

Although cryosurgery of oral tissues has been extensively studied, there is little information concerning healing and repapillation of the dorsum of the tongue. Using light, transmission, and scanning electron microscopy, an investigation of the sequence of reformation of papillae was carried out in the hamster. Four days postoperatively there was mitotic activity and cell migration at the periphery of the wound. At the edge of the ulcer there were partially damaged tongue papillae with evidence of recovery. Damaged papillae had regenerated completely within 2 weeks. In the central ulcerated area, epithelium healed by migration and, within this new epithelium, tongue papillae commenced to form by a process similar to that seen in the fetal tongue. Repapillation of the central area of the lesion was complete 6 weeks after operation, leaving minimal scarring. The details of these processes are described.     

Two histospecific enzyme expressions in the same cleavage-arrested one-celled ascidian embryos

Fertilized eggs of the ascidian, Ciona intestinalis, were prevented from undergoing cytokinesis but not nuclear division by treatment with cytochalasin B. After appropriate times, such cleavage-arrested multinucleate zygotes developed acetylcholinesterase of larval tail muscle and an alkaline phosphatase ordinarily localized in the larval endoderm tissues. Separate histochemical reactions on one of a pair of samples taken from the eggs of single animals provided examples (6/34) in which the numbers of cytochalasin-treated embryos displaying the respective reaction product overlapped sufficiently (15-29%) to indicate that some of the zygotes had developed both enzymes in the same uncleaved single cell. With an actual dual-staining technique that can be applied to single cleavage-arrested zygotes, 62% of those developing a strong alkaline phosphatase reaction also had a strong acetylcholinesterase reaction. In other experiments, quantitative measurements of enzyme activity in homogenates of 114 single cleavage-arrested zygotes confirm directly that 18% of the zygotes produce both enzymes. There was no obligatory mutual exclusion of the potential for simultaneous expression of two tissue-specific characteristics that would ordinarily be segregated into different lineages during early cleavages. The cytoplasmic determinants believed responsible for these histotypic expressions can apparently function independently in the same cell.     

Differentiation of tropomyosin-containing myofibrils in cleavage-arrested ascidian zygotes expressing acetylcholinesterase

Two muscle differentiation programs, acetylcholinesterase and tropomyosin-containing filaments and fibrils, occur together in the same cleavage-arrested zygotes (1-celled) of the ascidian Ciona intestinalis. Coexpression in such undivided but developing 'embryos' is consistent with the idea that separate elements of muscle differentiation are related at some regulatory level, perhaps through a single multi-gene regulatory factor. Fertilized Ciona eggs were exposed to cytochalasin B for 20 h and then briefly reacted histochemically for acetylcholinesterase activity. Strongly reacting specimens were selected and processed for transmission electron microscopy to reveal regions of muscle ultrastructure. Every acetylcholinesterase-reactive zygote tested contained muscle contractile elements; no example lacking acetylcholinesterase was found with myofilaments and myofibrils. As demonstrated by immunogold labelling, a polyclonal antibody to tropomyosin from Ciona adult body wall reacted differentially with the presumed ultrastructural muscle elements in cleavage-arrested zygotes. Site-specific reactions were also observed in larval tail muscle and the siphon muscles of postmetamorphic zooids.     

The synthesis and biological evaluation of non-peptidic matrix metalloproteinase inhibitors.

Novel sulfonamide matrix metalloproteinase inhibitors of general formula (9) were synthesised by a route involving a stereoselective conjugate addition reaction. Enzyme selectivity was found to be dependant on the nature of the sulfonamide substituents. Compounds (9f, 9q) are potent selective collagenase inhibitors with good oral bioavailability.