Supraordinal brachiopod classification

Three controversial problems of brachiopod supraordinal classification are discussed: the position of brachiopods in the classification of Metazoa, their classification at phylum and class level, and the classification of the articulate brachiopods. The position of brachiopods in the system of Metazoa remains uncertain. There are no strong reasons for changing the traditional division of the phylum Brachiopoda into the classes Inarticulata and Articulata. The class Articulata is divided into the subclasses Orthata, Strophomenata, Spiriferata, and Terebratulata.     

Burrowing of the lingulid brachiopod Glottidia pyramidata: its ecologic and paleoecologic significance

Contrary to popular assumption, the pedicle of Glottidia is not its principal burrowing organ. The brachiopod props itself up with the pedicle and enters the sediment with the valves leading, anterior end first. The pedicle trails behind. Burrowing is accomplished by cyclical valve motions: rotary, sliding, and gaping movements are used. Rapid valve closure ejects water from the mantle cavity to loosen the sediment. The lateral setae convey mucus-bound sand posteriorly (upwards). X-radiography shows that the burrows are U-shaped: in a few hours, the animal reappears in feeding position with the anterior end pointing out of the sediment and the pedicle extending down into the burrow. This burrowing process explains the substrate preferences of lingulids. The thick. closely spaced setae are adapted for burrowing. The spacing between individuals is increased, suggesting competition for food.     

Dental characters of the Quaternary tapirs in China, their significance in classification and phylogenetic assessment

Most of the Quaternary tapir fossils from China are isolated teeth. The purpose of this paper is to identify them and to extract systematic and evolutionary information from them. Based on morphology and W/L ratio, isolated teeth can be identified successfully. On the whole, the identification of P¹, M³ and P₂ is believed to be reliable, while it is difficult to distinguish P₃ from P₄, M₁ from M₂ etc. Concerning the variations of the teeth, P¹ is the most variable one in dimension. In the Quaternary tapirs in China, some dental characters can be used as reliable indicators to evaluate their evolutionary levels. The degree of the atrophy of the upper canine relative to the caniniform I³ is reflected in the C/I³ diameter ratio, which is decreasing during evolution. P¹ changes considerably in outline and strength of the hypocone. Some forms are without hypocone, such as Tapirus sanyuanensis, some have a very faint hypocone, such as Tapirus indicus; although most of them show a developed hypocone. For other cheek teeth, the W/L ratio is decreasing through geologic time. Two lineages can be tentatively proposed: one is the Tapirus peii-Tapirus sinensis-Megatapirus augustus progression; the other is the T. sanyuanensis-T. indicus lineage. T. sanyuanensis and T. peii stand on the base, and it is very probable that the latter is more primitive.     

Allosteric interactions in sipunculid and brachiopod hemerythrins

Chemical and spectroscopic consequences of allosteric interactions for ligand binding to sipunculid (Phascolopsis gouldii) and brachiopod (Lingula reevii) hemerythrins (Hrs) have been investigated. Possible allosteric effectors for homotropic effects in sipunculid Hrs have been examined, but only reduction in ligand affinity is observed without cooperativity. In contrast to sipunculid Hr, L. reevii Hr binds O2 cooperatively in the pH range 7-8 and exhibits a Bohr effect. Spectroscopic comparisons of the sipunculid and brachiopod Hrs show no significant differences in the active site structures; therefore, modulation of oxygen affinity is attributable to effects linking the site to quaternary structural changes in the octamer. Oxygen equilibria can be fit with a conformational model incorporating a minimum of three states, tensed (T), relaxed (R), and an R-T hybrid. Resonance Raman spectra of L. reevii oxyHr show a shift in the peroxo stretching frequency when the pH is lowered from pH 7.7 (predominantly R oxyHr) to pH 6.3 (a mixture of R, T, and R-T hybrid), but P. gouldii Hr does not have a frequency shift under the same conditions. In contrast to hemoglobins, ligand binding to the deoxy and met forms is noncooperative for brachiopod (and sipunculid) Hrs. It is thus suggested that conformational changes in the protein are linked to the oxidation state change that accompanies oxygenation of the coupled binuclear iron site (deoxy [FeIIFeII]----oxy [FeIIIFeIII]). The total allosteric energy expended in oxygenation is about 1.4 kcal/mol, and such a shift is possible in the relaxed-tense conversion with relatively limited constraints of the iron coordination environment via the protein quaternary structure. The mechanism of cooperativity in the binuclear copper oxygen carrier hemocyanin is discussed in light of these results.     

Ecological significance and classification of Chinese wetlands

China supports a great variety of wetlands, including some of the most important in the world. However, an appropriate classification system applicable to all wetlands is not available. Based on a preliminary inventory, a new classification system for Chinese wetlands is proposed. This system classifies natural wetlands into three categories on the basis of their natural features and distribution: peatlands, coastal and estuarine wetlands, and riverine and lacustrine wetlands. Each category is divided into several sub-classes. The areal extent of wetlands in each Province has been estimated and their ecological importance assessed.     

Ultrastructural studies on the brachiopod pedicle

Studies of the ultrastructure of representative articulate and inarticulate pedicles show that there are similarities in secretory activity between pedicle epithelia of both classes and the outer mantle epithelium of the inarticulates. Rootlet epithelial cells of the articulate pedicle produce small vesicles which pass to the junction between rootlet and substrate and probably play a part in the breakdown of the substrate. Scanning electron microscopy shows that dissolution of a bivalve shell acting as a substrate often follows the boundary of a single nacre tablet, and transmission electron microscopy shows that the rootlet extends its infiltration along the conchiolin walls. The inarticulate pedicle ending is modified to collect adherent sand grains.     

Nerves in the endodermal canals of hydromedusae and their role in swimming inhibition

N eoturris breviconis (Anthomedusae) has a nerve plexus in the walls of its endodermal canals. The plexus is distinct from the ectodermal nerve plexuses supplying the radial and circular muscles in the ectoderm and no connections have been observed between them. Stimulation of the endodermal plexus evokes electrical events recorded extracellularly as “E” potentials. These propagate through all areas where the plexus has been shown by immunohistology to exist and nowhere else. When Neoturris is ingesting food, trains of “E” potentials propagate down the radial canals to the margin and cause inhibition of swimming. This response is distinct from the inhibition of swimming associated with contractions of the radial muscles but both may play a part in feeding and involve chemoreceptors. Preliminary observations suggest that the “E” system occurs in other medusae including Aglantha digitale (Trachymedusae) where the conduction pathway was previously thought to be an excitable epithelium.     

Larval structures of oxytorines and their significance for the higher classification of some Ichneumonidae (Hymenoptera)

The phylogenetic relationships of the Acaenitinae, Oxy-torinae, and some of their component taxa, especially Cylloceria and Microleptes , are considered in light of new data from larval morphology. The Acaenitinae and Oxytorinae are sister-groups; the enigmatic oxytorine genus Microleptes is analysed with regard to its larval characters and is placed in to its own subfamily, the Microleptinae. The possibility that the Oxytorinae may be paraphyletic with respect to the Orthocentrinae is discussed. Re-examination of original slide mounts of last-instar larval remains has revealed errors in past studies; all previously published material, and several taxa whose larvae were hitherto unknown, are figured.     

Fascia canals of the greater sciatic foramen and their practical importance

Fasciae and fat tissue spaces in the gluteal region, topography of the suprapiriform and infrapiriform foramina have been studied by means of a complex anatomical experimental technique. The suprapiriform foramen should be considered as a fascialosseous canal, as it is 4-4.5 cm long and 0.6-1.0 cm wide. It is formed by the upper margin of the greater sciatic notch covered with a thin fascia, fasciae of the gluteal and piriform muscles and the parietal layer of the pelvic fascia. The proper fascial vaginae of the upper gluteal vessels and nerves are adhered to fascial walls of the canal. This peculiarity is used for the method of ligation of the superior gluteal artery within the limits of the suprapiriform canal. The infrapiriform foramen is either narrow or wide enough (up to 2.0 cm in diameter). Inferior gluteal vessels at the level of the sacrospinous ligament go from the parietal layer of the pelvic fascia into the duplicature of the deeper layer of musculus gluteus maximus. The inferior gluteal nerve, above the lower margin of the piriform muscle, ajoining the vessels gets into the fissure of the parietal layer of the pelvic fascia, under the lower margin neurovascular fasciculus also goes through the fissure of the pelvic fascial parietal layer, downward and parallel to the inferior gluteal vessels. The knowledge of possible ways of connections through the canals of the greater sciatic foramen, fat tissue spaces at the subperitoneal level of the small pelvis and the gluteal region is of great practical value.     

Ribbing patterns in the brachiopod Diceromyonia

Ribbing patterns in two collections of the Ordovician brachiopod Diceromyonia from central North America are compared using the system invented by Bancroft (1928; Manchester Memoirs 72 ) for naming ribs. Simple and nearly symmetric arrangements of frequently occurring branches characterize both collections, with much of the complexity evident in larger valves due to irregular occurrence of low-frequency branches on either side of major ribs. Examination of median sectors reveals little support for Bancroft's derivation of the rhipidomelloid midrib from isorthoid forms, and an alternative non-evolutionary interpretation is proposed in which median patterns appear as predictable outcomes of a simple space-filling process. The approximately 2500 ribs identified in this study are treated as a population in their own right: orderly patterns which emerge are not inferred but are simple summaries of complete counts, obtained by hand. This approach is quick and painless compared to methods using order relations to assess ribbing differences in dalmanellid brachiopods. For this reason, it may encourage systematic study of ribbing patterns among these taxa and lead ultimately to better understanding of the utility of ribbing in their taxonomy.     

New fungal classification and their applications in medicine

Fungi are gaining importance with the increased incidence of invasive, often fatal mycoses, in immunocompromised patients. In addition, the increased number of emerging opportunistic pathogens has prompted interest in studies pertaining to fungal classification. The traditional methods of identification and classification of these microorganisms are based on the morphology of the sexual and asexual reproductive structures. Recently, this system of classification has been shown incongruent with approaches that better establish phylogenetic relationships among these organisms. Novel aspects of fungal reclassification are described as follows: 1) the position of fungi in the historical classification systems, 2) the recognition of their polyphyly, based on comparative studies of nucleic acid sequences and on analysis of descent lines and, 3) the contribution of molecular phylogeny to medical mycology, including identification of mycotic agents, their molecular epidemiology, prevention of infection and methods of diagnosis.     

Macromolecules in brachiopod shells: characterization and diagenesis

An immunological investigation was conducted of soluble intra-crystalline macromolecules isolated from living and fossil brachiopod shells, which had previously been used for an immunologically based study of phylogeny (serotaxonomy). The soluble intra-crystalline macromolecules comprised 0.03% by weight of the extant shell material. Bulk analysis and gel electrophoresis indicated that the organic material is predominantly glycoprotein, and contains up to 30% by weight carbohydrate. Treatment of the macromolecules with periodate and proteinase K revealed that antibodies were raised predominantly against the carbohydrate moieties. Using a specially adapted dot blot immunobinding assay (DIBA) the decay in immunological signal over geological time was determined. Pleistocene shells have lost between 99 and 99.9% of immunological reactivity, and original antigenic determinants form a declining proportion of total organic matter. It is suggested that condensation reactions between amino acids and sugars account for the rapid destruction of determinants; this has important implications for the direction of future studies on fossil macromolecules. □ Serotaxonomy, biomolecular palaeontology, glycoproteins, melanoidins, brachiopods.     

Statistical indices in medicine and epidemiology and their classification

Mathematical statistics deals with abstract notions, while medicine solves complicated and many-sided problems. For this reason medical statistics faces some moot points in the interpretation of a number of notions and the classification of statistical indices. In the present article the definition of variables and statistical indices is formulated and their characterization is given. An attempt is made to provide the systematization and natural classification of the latter. Statistical indices are defined as the characteristics of statistical totalities. To classify statistical indices, the most essential signs are used: the character of a variable (external relations), the trend of study (internal content), the form of expression (calculation), derived indices and characteristics (comparison and the results of analysis).     

Pollen vacuoles and their significance

Vacuoles of several types can be observed in pollen throughout its development. Their physiological significance reflects the complexity of the biological process leading to functional pollen grains. Vacuolisation always occurs during pollen development but when ripe pollen is shed the extensive translucent vacuoles present in the vegetative parts in previous stages are absent. Vacuole functions vary according to developmental stage but in ripe pollen they are mainly storage sites for reserves. Vacuoles cause pollen to increase in size by water accumulation and therefore confer some degree of resistance to water stress. Modalities of vacuolisation occur in pollen in the same manner as in other tissues. In most cases, autophagic vacuoles degrade organelles, as in the microspore after meiosis, and can be regarded as cytoplasm clean-up following the transition from the diploid sporophytic to the haploid gametophytic state. This also occurs in the generative cell but not in sperm cells. Finally, vacuoles have a function when microspores are used for pollen embryogenesis in biotechnology being targets for stress induction and afterwards contributing to cytoplasmic rearrangement in competent microspores.