Carbonic Anhydrases in Chick Extra-embryonic Structures: A Role for CA in Bicarbonate Reabsorption Through the Chorioallantoic Membrane

The villus cavity cells, a specific cell type of the chick chorioallantoic membrane, express both cytosolic carbonic anhydrase in their cytoplasm and [Formula: See Text] anion exchangers at their basolateral membranes. By immunohistochemical analysis, we show here that villus cavity cells specifically react with antibodies directed against the membrane-associated form of carbonic anhydrase, CAIV. Staining is restricted to the apical cell membranes, characteristically invaginated toward the shell membrane, as well as to endothelia of blood vessels present in the mesodermal layer. The occurrence of a membrane-associated CA form at the apical pole of villus cavity cells, when definitively confirmed, would be fairly consistent with the role proposed for these cells in bicarbonate reabsorption from the eggshell so to prevent metabolic acidosis in the embryo during development.     

Reassessment of the vocal repertoire of a nest-building gladiator frog,Boana pardalis (Anura,Hylidae, Cophomantinae): implications for its diagnosis within the B. faber species group

In this study, we re-describe the advertisement and territorial calls of Boana pardalis, carry out an acoustic comparison between the studied species and the other congeners of the B. faber group, and report for the first time the tympanic amplexus for the studied species. The advertisement call of B. pardalis can be used to supplement its diagnosis in the B. faber group based on temporal call traits, e.g. emission rate and emission pattern, as well as the call envelope.     

When an epithelium ceases to exist – an ultrastructural study on the fate of the embryonic coelom in Epiperipatus biolleyi (Onychophora, Peripatidae)

It is an accepted fact that fusion between the coelomic cavities and the primary body cavity occurs during development in the Arthropoda. However, such a fusion is much disputed in the Onychophora. In order to clarify this subject, the fate of embryonic coelomic cavities has been studied in an onychophoran. Ultrastructural investigations in this paper provide evidence that embryonic coelomic cavities fuse with spaces of the primary body cavity in Epiperipatus biolleyi. During embryogenesis, the somatic and splanchnic portions of the mesoderm separate and the former coelomic linings are transformed into mesenchymatic tissue. The resulting body cavity therefore represents a mixture of primary and secondary (coelomic) body cavities, i.e. the ‘mixocoel’. The nephridial anlage is already present, when the ‘mixocoel’ is formed, although there is no trace of a sacculus yet. The lumen of the nephridial anlage, thus, communicates with the newly formed ‘mixocoel’. Accordingly, the lumen of the nephridial sacculus cannot be regarded as a kind of ‘persisting coelomic cavity’ in E. biolleyi. Our findings support the hypothesis that the ‘mixocoel’ was already present in the common stem species of the Onychophora and Euarthropoda.     

气孔下腔间的水汽扩散

本文把气孔及其下腔看作截面为椭圆形的柱形区域,提出一个水汽从气孔下腔内所有细胞表面扩散到气孔外端的三维扩散模型。根据 Fick 定律和质量守恒定律建立了支配该模型的水汽扩散方程。用有限差分法,借助于计算机求得水汽从气孔下腔的所有细胞表面扩散到气孔内端所遇到的阻力及其近似表达式。并从理论上对该阻力的倒数——导度随气孔面积而变化的方式做了分析和解释。通过将本模型求得的气孔下腔阻力计算公式与 Brown 等以及 Cooke 的公式比较,发现在气孔开度变化相当大的范围内用后面两公式计算的阻力偏大0.5—1倍左右。此外,计算结果还表明:在气孔下腔水散失总量中,腔内表皮细胞表面上的水散失量占86—96%,而保卫细胞表面上的水散失量又占后者的88—93%,副卫细胞表面上的水散失量仅7—12%。     

Fructan contents and dry matter deposition in different tissues of the wheat grain during development

The role of fructan metabolism in the assimilate relations of the grain of wheat (Triticum aestivum L.) was investigated by determination of the dry matter and fructan content of grain components at short intervals during grain filling. During the initial phase of rapid expansion, most of the assimilates entering the grain were partitioned to the outer pericarp. A large fraction of these assimilates were used for the synthesis of fructan. Dry matter deposition and fructan synthesis in the outer pericarp ceased at about 5d after anthesis. At the same time, the endosperm and the inner pericarp and testa started to accumulate dry matter at a fast rate. This was also associated with significant fructan synthesis in the latter tissues. The outer pericarp lost about 45% of its former maximum dry weight between 9 and 19 d after anthesis. This loss was due almost entirely to the near complete disappearance of water-soluble carbohydrates, most of which was fructan. The inner pericarp and testa accumulated dry matter until about mid-grain filling. The fructan contents of the inner pericarp and testa and the endosperm decreased slowly towards the end of grain filling. Most of the fructans in the inner pericarp and testa and the endosperm had a low molecular weight, whereas higher molecular weight fructans predominated in the outer pericarp. The embryo did not contain fructan. The presence of low molecular weight fructans in the endosperm cavity at mid-grain filling was confirmed. It is suggested that fructan synthesis is closely linked to growth-related water deposition in the different tissues of the wheat grain and serves to sequester the surplus of imported sucrose.     

人类口腔小生境微生物的多样性

本文论述了人类口腔中微生物的物种多样性,口腔小生境的复杂性与微生物多样性的关系,以及口腔中微生物变化与人类疾病和健康的关系。     

Theoretical and experimental determination of SAR patterns for spherical tissue models in a rectangular resonant cavity

Specific absorption rates (SARs) were determined theoretically and experimentally for several spherical models of tissue exposed to electrical fields of TE101 mode in a rectangular cavity of 57.3 MHz resonant frequency. The approximate theoretical SAR can be calculated according to the Mie theory by superposition of four plane waves representing the fields excited in the cavity. The theoretical and thermographically determined SAR patterns in spheres with radii of 5, 7.5, and 10 cm and with conductivities of 0.1, 1, and 10 S/m were compared. For a sphere with radius less than 7.5 cm and conductivity less than 1 S/m, the SAR was quite uniform. When conductivity was increased to 10 S/m, the SAR patterns showed higher absorption in the periphery of the largest sphere (10-cm radius). These characteristics are important in evaluating the scaling technique of exposing a model of a human to very-high-frequency fields to obtain power absorption data in humans exposed to high-frequency or very-low-frequency fields.     

B-cells of the synovial membrane. II. Differentiation during development of the synovial cavity in the mouse

Summary Study of pre- and postnatal development of the metatarsophalangeal joint of the mouse shows that the synovial cavity (SC) forms before any differentiation of the synovial mesenchyme. The primitive cleft results from degradation of a thin vascular mesenchymal layer in direct contact with the chondrogenic layers. Differentiation of the synovial membrane coincides with clarification of the SC (3rd to 6th day of postnatal life). When dilatation of the SC occurs (6th to 8th day), the two intimal cells types (A- and B-cells) are well identified. The B-cells already show typical features at day 6; their content of typical dense secretory vesicles is comparable to that of the adult B-cells at day 13. The specific secretory function of B-cells could be correlated with the particular structure of the intimal interstitial tissue and could account for the origin of some protein(s) of the synovial fluid.ERA 178 (Neuroendocrinologie Comparée) du CNRS et INSERM     

The goblet cavity matrix in the larval midgut of Hyalophora cecropia

The larval midgut of the silkmoth Hyalophora cecropia was examined using scanning electron microscopy. Goblet cells were observed to contain within their cavities a matrix plug. This matrix material was extruded onto the lumen side of the epithelium when the tissue was stretched. The rôle of this matrix material in maintenance of the capacity of the midgut to transport ions in vivo and in vitro is discussed.