Functional morphology of synarthrial articulations in the crinoid stem

Synarthrial fulcral ridges are found in crinoid columnals from the mid-Ordovician to the present and in all four subclasses. Similar articulations did not become common in the cirri until the Mesozoic. Synarthrial stem articulations fall into two broad groups. Type I articulations have a fulcral ridge in the centre of the articular facet. In elliptical ossicles this ridge corresponds to either the long (IA) or short (IB) axis of the facet. Although both are functionally similar, Type IA ossicles are more common. Type II articulations have an excentric fulcral ridge, parallel to either the long (IIA) or short (IIB) axis of the articular facet. Type IIA articulations are found in crinoid stems capable of coiling. Type II articulations are particularly common in the cirri of articulates and are well adapted for attachment to hard and soft substrates. Columnals with Type I articulations often have divergent fulcra, giving the stem flexibility in all directions, but this feature is not seen in cirri or in coiled stems, where it would impair normal functions. Only the cirri of isocrinids and comatulids are muscular, so the movement of columns with fulcra must be passive.     

Phylogenetic interrelationships of the barbets (Aves: Capitonidae) and toucans (Aves: Ramphastidae) based on morphology with comparisons to DNA-DNA hybridization

A phylogenetic analysis of the interrelationships of the barbets (Capitonidae) and the toucans (Aves: Ramphastidae, Superfamily Ramphastoidea) is presented. Thirty-two morphological characters from the literature and independent osteological observations were analysed. Character polarity was determined by outgroup comparison to the Picidae, Indicatoridae, Galbulidae, Bucconidae and Coraciiformes. Four alternative phylogenetic hypotheses were compared: (1) the overall most parsimonious morphological phylogeny, (2) the most parsimonious morphological phylogeny in which the capitonids and ramphastids were hypothesized as monophyletic sister groups, and (3) and (4) the most parsimonious hypotheses for the evolution of the morphological characters within two proposed DNA-DNA hybridization phylogenies of the ramphastoids. The analysis focused on the higher level relationships of ramphastids and capitonids and interrelationships among capitonid genera. Two cladistic analyses were performed using 26 phylogenetically informative characters, and the PAUP and CONTREE computer alogorithms. The most parsimonious morphological phylogeny required fewer character changes and had a lower consistency index than any of the alternative hypotheses but congruence between the most parsimonious phylogeny and the second, revised DNA-DNA hybridization hypothesis was very high. Based on these results the monophyly of the Capitonidae is rejected. The ramphastids and the Neotropical capitonids form a well corroborated clade within the pantropical ramphastoid radiation. Neither the African, Asian nor New World capitonids is monophyletic. The genus Trachyphonus is the sister group to all other capitonids and ramphastids. The sister group to the ramphastids is the genus Semnornis. The interrelationships of the Old World capitonids excluding Trachyphonus are not completely resolved by these morphological data but one of the alternative phylogenetic resolutions is presented as a preliminary hypothesis. The clades in this resolved phylogeny are diagnosed and the palaeontology and biogeography of the ramphastoids arc-reviewed in light of this new evidence. A phylogenetic classification is proposed in which the Capitonidae is rejected and the capitonids and ramphastids are placed in seven subfamilies of the Ramphastidae.     

Nonenzymatic isolation and culture of adult islets from atrophic pancreata of copper-deficient rats: A morphologic analysis

Summary The purpose of this study was to develop a nonenzymatic method of isolating adult islets using atrophied pancreata from copper-deficient rats and to analyze their morphologic characteristics and behavior in culture. This unusual model of isolation was studied because islets remain intact in the course of dietary copper deficiency while the acinar glandular component of the pancreas undergoes selective atrophy and lipomatosis. Small fragments containing islets were readily microdissected from atrophied glands and placed in culture. Within 24 h the fragments congealed into small irregular- to spherical-shaped masses within which the darker profile of islets could be distinguished. Within a period of 3 to 5 d, islet tissue began to bud from the lipocytic mass until by Day 7 spherical aggregates of intact islet tissue separated from the residual fragments. Subsequent to further in vitro treatment, these islets could be maintained as free viable spherical masses if periodically agitated, as attached stationary islets which developed monolayer growth if left undisturbed and as aggregated masses of islet tissue forming megaislets if combined in small groups. Grouped islets treated with actinomycin D and cycloheximide did not exhibit aggregation when incubated with these inhibitors. This suggests that megaislet formation was an active process requiring protein-RNA synthesis rather than passive clumping or aggregation that can accompany metabolically altered or dying islets undergoing cellular shedding and adhesion. Immunohistochemical localization demonstrated that insulin, glucagon, somatostatin, and pancreatic polypeptide-immunoreactive cell types were present within the islets derived from this technique. The cellular topography of these islets was not unlike that described by others for islets cultured from enzymatic isolation. This culture model may serve as a resource for mature, viable islets isolated without mechanical or enzymatic disaggregation which can have attenuating effects on islet function. This work was supported by a research grant from the Diabetes Research and Education Foundation.     

A factor produced by human cells in vitro that changes HeLa cell colonial morphology

Summary Colonies of HeLa cells cultured in media supplemented with human or bovine serum or both can be morphologically described as three types: diffuse, intermediate, and compact, with their modal distribution depending on the serum or sera added to the growth medium. We have observed that for a particular medium or serum system, the percentage of compact colonies remains fairly constant under normal culture conditions, 0.2%, whereas the diffuse and intermediate colonies vary over a much wider range. The presence of certain substances as trypsin, heparin and Darvan in the medium favor the increase of compact colonies at the expense of other types. Furthermore, we have discovered that colonial morphology is influenced by cocultivation of the HeLa cells with human fibroblastlike cells, the compact colonies increasing as the density of the fibroblast element introduced into the mixed cultures is increased. Subsequent investigation revealed that conditioned medium from confluent fibroblast and HeLa cell cultures contained a factor(s), that significantly increased the percentage of compact colonies. The factor is nondialyzable, heat-stable and can be neutralized by serum. Recorded in this presentation are preliminary observations on the kinetics of colony formation and the interaction among the three HeLa cell colony types, the diffuse, the intermediate, and the compact. The factor's effect on HeLa cell colonial morphology is time dependent and rapidly reversed if the factor(s) is removed and fresh medium added.     

Phytochemical and morphological support for the existence of two species inMonoclea (Hepaticae)

Recognition of two different species in the liverwort genusMonoclea Hook. (monotypic orderMonocleales), viz.M. forsteri Hook. in New Zealand andM. gottschei Lindb. in the New World, is supported by characteristics of the sporophyte, antheridial receptacle and secondary metabolites.M. gottschei produces the greatest variety of flavonoids and the largest amount of bisbibenzyls ever encountered in a liverwort. In contrast,M. forsteri is poor in secondary metabolites. Two allopatric subspecies are recognized inM. gottschei, based on characteristics of the antheridial receptacle: subsp.gottschei in Chile (Valdivian region, Juan Fernandez Is.) and subsp.elongata Gradst. & Mues, subsp. nova, in tropical America. The exclusive occurrence inMonoclea of glucuronide and galacturonide flavone glycosides and the fact that capsule dehiscence may take place before full elongation of the seta are new arguments in support of the placement ofMonocleales in theMarchantiidae. Publication Nr. 43 of the Arbeitskreis Chemie und Biologie der Moose, Universität des Saarlandes, Saarbrücken. This paper is dedicated to DrElla O. Campbell, Massey University, Department of Botany and Zoology, New Zealand on the occasion of her 80th birthday.     

Phylogenetic evidence for the herbaceous origin of angiosperms

The ancestral angiosperm is commonly interpreted as an arborescent to shrubby magnolialean with large, multiparted, complex flowers. We examined this hypothesis using a phylogenetic analysis of new and reevaluated characters polarizabled with outgroup comparison. Our cladistic analysis of basal angiosperms placed the nonmagnolialeanChloranthaceae andPiperaceae at the bottom of the tree. We further inferred the probable ancestral states of characters not polarizable with outgroup comparison by examining their distribution among taxa at the base of our cladogram. The sum of ancestral character states suggests that the protoangiosperm was a diminutive, rhizomatous to scrambling perennial herb, with small, simple flowers.     

Gene variation and gene flow inOrchis morio (Orchidaceae) from Italy

Data are presented on genetic variation at 27 enzyme loci of the Green-Winged orchid,Orchis morio, in 18 population samples from Italy. The existence in Italy of two subspecies, i.e. subspp.morio andpicta, is not supported by allozyme data. No genetic heterogeneity was found betweenmorio-like andpicta-like samples and specimens. Moreover, morphological transition between the two forms was observed in different Italian populations. The parameters of genetic variability estimated forO. morio populations are consistent with those found among monocotyledon plants, and among those outcrossing, animal-pollinated and with wind-dispersed seeds. Genetic diversity of ItalianO. morio is mostly within populations. Correspondingly, low values of interpopulational genetic distance were found. This appears to be due to high levels of gene flow, which were estimated with different methods. The lack ofO. longicornu from Italian samples, as well as of any hybrid withO. morio (F₁, backcrossed or recombinant individuals) is demonstrated on the basis of genetic data. It is concluded that recurrent reports ofO. longicornu from Italy are due to confusion withO. morio or with otherOrchis species.     

Estimates of hierarchical variation in flower morphology in natural populations ofScleranthus annuus (Caryophyllaceae), an inbreeding annual

The variation in two sets of morphological characters of the flowers of the highly inbreedingScleranthus annuus (Caryophyllaceae) was assessed using 15–20 plants from each of 20 natural populations from the southernmost region of Sweden. The stamen fertility data set consisted of 10 characters describing the degree of fertility of the ten stamens/staminoids, while the sepal/gynoecium data set comprised 10 sepal characters, together with style and stigma length. Substantial variation was found in both the degree of development and the fertility of the stamens, the degree of variability in stamen fertility being related to stamen position within the flower. Considerable variation was found in the characters of the sepal and the gynoecium. Hierarchical analyses of variance indicated that 29% of the variation in total male reproductive effort was distributed among populations, 28% among plants within populations and 43% represented within-plant variation. The corresponding averages for the characters from the sepal/gynoecium data set are 26, 38, and 35%: a greater proportion of the total variance in female reproductive characters is accounted for by among individual variation than is the case with the male reproductive characters. Significance tests of Mahalanobis distances derived by canonical variate analyses indicated that all populations were significantly separated using the sepal/gynoecium data set, while only 50% of the pairwise comparisons on the basis of the stamen fertility data set were significant. Cluster analysis did not reveal any aggregation of the populations. The incongruence of the two data sets and their ability to discriminate between the populations is discussed.     

Genomic groups,morphology, and sectional delimitation in EurasianElymus (Poaceae,Triticeae)

Seven tetraploid species ofElymus, viz.E. sibiricus, E. caninus, E. gmelinii, E. semicostatus, E. caucasicus, E. parviglume, andE. longearistatus subsp.canaliculatus, representing five sections were studied morphologically and used in interspecific hybridizations. The aim was to investigate whether the present sectional delimitation of the genus was in agreement with genomic data and if there was a correlation between genome constitution and morphology. The study revealed: (i) further information on the genomic affinities between the different species, (ii) that there is no congruence between genome constitution of the species and current sectional delimitation, and (iii) that there is a correlation between genome constitution and morphology in the palea apex shape and in the size of cilia of the palea.