Gross intestinal morphometry and allometry in primates

Although it is generally assumed that among mammals and within mammal groups, those species that rely on diets consisting of greater amounts of plant fiber have larger gastrointestinal tracts (GIT), statistical evidence for this simple claim is largely lacking. We compiled a dataset on the length of the small intestine, caecum, and colon in 42 strepsirrhine, platyrrhine, and catarrhine primate species, using specimens with known body mass (BM). We tested the scaling of intestine length with BM, and whether dietary proxies (percentage of leaves and a diet quality index) were significant covariates in these scaling relationships, using two sets of models: one that did not account for the phylogenetic structure of the data, and one that did. Intestine length mainly scaled geometrically at exponents that included 0.33 in the confidence interval; Strepsirrhini exhibited particularly long caeca, while those of Catarrhini were comparatively short. Diet proxies were only significant for the colon and the total large intestine (but not for the small intestine or the caecum), and only in conventional statistics (but not when accounting for phylogeny), indicating the pattern occurred across but not within clades. Compared to terrestrial Carnivora, primates have similar small intestine lengths, but longer large intestines. The data on intestine lengths presented here corroborate recent results on GIT complexity, suggesting that diet, as currently described, does not exhaustively explain GIT anatomy within primate clades.     

Cell size of proliferating plant cells increases with temperature: implications in the control of cell division

As chemical reactions related to the regulation of cell proliferation are governed by availability, amount, and concentration of relevant molecules, it has been suggested that cell size is an important factor in the control of cell cycle. We have measured the size of proliferating cells of Allium cepa roots in which growth rate was modified by changes in growth temperature. Two independent cell size parameters have been measured by cytophotometry: cell surface area projection and cell protein content. Average cell sizes of both the proliferating cell population and the subpopulation at the end of mitosis show that cell size increases with growth rate. Calculation of cell size at initiation of DNA replication clearly indicates that average cell size at this point is not growth invariant but positively correlated with growth rate.     

Cladistic analysis of the Cirripedia Thoracica

We present a cladistic analysis of the Cirripedia Thoracica using morphological characters and the Acrothoracica and Ascothoracida as outgroups. The list of characters comprised 32 shell and soft body features. The operational taxonomic units (OTUs) comprised 26 well-studied fossil and extant taxa, principally genera, since uncertainty about monophyly exists for most higher ranking taxonomic units. Parsimony analyses using PAUP 3.1.1 and Hennig86 produced 189 trees of assured minimal length. We also examined character evolution in the consensus trees using MacClade and Clados. The monophyly of the Balanomorpha and the Verrucomorpha sensu stricto is confirmed, and all trees featured a sister group relationship between the ‘living fossil Neoverruca and me Brachylepadomorpha. In the consensus trees the sequential progression of ‘pedunculate‘sister groups up to a node containing Neolepas also conforms to current views, but certain well-established taxa based solely on plesiomorphies stand out as paraphyletic, such as Pedunculata (= Lepadomorpha); Eolepadinae, Scalpellomorpha and Chthamaloidea. The 189 trees differed principally in the position of shell-less pedunculates, Neoverruca, the scalpelloid Capitulum, and the interrelationships within the Balanomorpha, although the 50% majority rule consensus tree almost fully resolved the latter. A monophyletic Sessilia comprising both Verrucomorpha and Balanomorpha appeared among the shortest trees, but not in the consensus. A tree with a monophyletic Verrucomorpha including Neoverruca had a tree length two steps longer than the consensus trees. Deletion of all extinct OTUs produced a radically different tree, which highlights the importance of fossils in estimating cirripede phylogeny. Mapping of our character set onto a manually constructed cladogram reflecting die most recent scenario of cirripede evolution resulted in a tree length five steps longer than any of our shortest trees. Our analysis reveals that several key questions in cirripede phylogeny remain unsolved, notably the position of shell-less forms and the transition from ‘pedunculate‘to ‘sessile‘barnacles. The inclusion of more fossil species at this point in our understanding of cirripede phylogeny will only result in even greater levels of uncertainty. When constructing the character list we also identified numerous uncertainties in the homology of traits commonly used in discussing cirripede evolution. Our study highlights larval ultrastructure, detailed studies of early ontogeny, and molecular data as the most promising areas for future research.     

Distribution of ABO blood groups and other genetic markers in mothers of infants with congenital malformations

The distribution of ABO and Rh (antigen D) blood groups and of serum albumin, haptoglobin and transferrin variants, in a group of mothers of malformed newborns was investigated. In the first phase of the study, the results showed borderline statistical differences in the distribution of the transferrin types between the study group and a suitable control population. The second phase of the research, where only transferrin phenotypes were studied, showed the same trend as in the first one, but the results were not statistically significant. We conclude that probably there are no true distribution differences, but that it would be desirable to study this problem in a different ethnic group.     

Thidiazuron stimulates shoot organogenesis and somatic embryogenesis in white ash (Fraxinus americana L.)

Immature and mature nonstratified seeds of white ash (Fraxinus americana L.) were dissected transversely and 2/3 of each seed was placed onto agar-solidified Murashige and Skoog medium. Adventitious buds, shoots, and somatic embryos formed on callus, cotyledons, and hypocotyls of the resulting seedlings. Shoot organogenesis was induced on explants cultured on medium with 10 M thidiazuron but not on explants on media with benzyladenine (BA) or isopentenyladenine. Not all seed sources were equally capable of shoot organogenesis and embryogenesis. Atypical of adventitious regeneration of other woody plants, mature seed explants of white ash were more organogenic with shoots that elongated better than explants from immature seeds. Somatic embryogenesis was observed in cultures where mature seeds were first cultured for 4 weeks on a medium containing 10 M adenine 2,4-dichlorophenoxyacetic acid in combination with 0.1 and 1.0 M thidiazuron, followed by transfer to a medium containing 0.05 M 6-benzyladenine and 0.5 M naphthaleneacetic acid. Adventitious shoots and epicotyls from both seedlings and germinated somatic embryos were rooted under intermittent mist and acclimatized to the greenhouse.Abbreviations BA 6-benzyladenine - 2,4-d 2,4-dichlorophenoxyacetic acid - IBA indolebutyric acid - 2iP isopentenyladenine - NAA naphthaleneacetic acid - TDZ thidiazuron-N-phenyl-N-1,2,3-thiadiazol-5-ylurea - WPM woody plant medium     

Dynamics of the nuclear envelope during cell cycle in plants

Stereology of Allium cepa root meristem cells was done to evaluate changes in the nuclear envelope during cell cycle. A naturally synchronous population was labelled as binucleate by caffeine inhibition of cytokinesis. Growth of the nuclear envelope preferentially occurs from mid G2 to the next mid G1, most probably in relation to the reforming sister nuclei after mitosis. On the other hand, the number of nuclear pores doubles from mid G1 to mid G2, their growth rate being higher in the first half of interphase (from mid G1 to mid S). Hence, the new nuclear envelope probably lacks nuclear pores, which appear later.     

Sylvatic trichinellosis in southwestern Spain

The epidemiology of Trichinella spp. in their main sylvatic hosts, wild boar (Sus scrofa ferus and red fox (Vulpes vulpes), in Extremadura (southwestern Spain) was studied. We examined 88 Trichinella spp.-positive wild boar muscle-tissue samples from a total of 29,333 killed animals, referred to the Veterinary Parasitology Department (University of Extremadura, Spain) by the Extremadura Veterinary Service. Additionally, 227 red foxes killed during the hunting season and thus not subject to veterinary controls were examined for trichinellosis. Trichinella spp. larvae were found in six (3%) of the red foxes. All samples were examined using direct diagnostic techniques, including trichinoscopy and artificial digestion. The mean intensity of infection was 74.8 larvae/g (LPG) of muscle tissue in wild boars, compared to 30.6 LPG in foxes. Trichinella spiralis (sensu stricto) predominated over T. britovi in wild boars. Random amplified polymorphic DNA (RAPD) and alloenzyme typing showed that 74% of infected wild boars had only T. spiralis, 21% had only T. britovi, and 5% showed mixed infections. In contrast, 33% of infected foxes were infected only with T. spiralis, while 67% had T. britovi, suggesting a clear predominance of the latter in foxes. We suspect the existence of a paranthropic or sylvatic cycle in large areas of this region; given the ease of transfer between sylvatic and domestic or semi-domestic animals, this implies a high epidemiological risk.     

Cloning and expression in a heterologous host of the complete set of genes for biosynthesis of the Streptomyces coelicolor antibiotic undecylprodigiosin

A fragment of DNA carrying the hitherto unisolated members of the cluster of genes (red) for biosynthesis of the red-pigmented antibiotic undecylprodigiosin of Streptomyces coelicolor A3(2) was isolated. This was done by cloning random fragments of S. coelicolor DNA into the closely related Streptomyces lividans 66 and recovering a clone that caused overproduction of undecylprodigiosin. The effect was probably due to the presence of the cloned redD gene, which functions as a positive regulator of the expression of the red cluster, activating the normally poorly expressed red genes of S. lividans. Two fragments from either end of the red cluster were cloned adjacent to each other on a low-copy-number Streptomyces vector. Double crossing-over occurring between these plasmid-borne sequences and the chromosomal copy of the same DNA in S. coelicolor led to isolation of the entire red cluster as a single cloned fragment. Isolation of antibiotic biosynthetic genes by the effects of an activator in a self-cloning experiment, and in vivo reconstitution of a large cluster of genes by homologous recombination, may turn out to be usefully generalizable procedures.