Morphology and development of the cranium of Felis silvestris f. catus Linné 1758--a contribution to the comparative anatomy of the Carnivora. II. Orbitotemporal region

In Felis 1, the orbitotemporal region is very compressed in rostrocaudal direction. As a result, most structures are tightly pressed together. Continuing development towards the stage of Felis 2, the cranium becomes remarkably elongated in this region. In early embryonic stage, Felis builds up a primary side wall, being remarkable complete. The following development towards Felis 1 and 2 gives an interesting example for the elements changing their configuration and position during ontogenesis and thereby illustrates the problems of interpreting these conditions phylogenetically and systematically: There is an evident reduction of the structures of the primary side wall and positional changes of the whole side wall at the same time.     

Leaf anatomy as a contribution to the taxonomy of Salacioideae N.Hallé ex Thorne & Reveal (Celastraceae)

The current classification systems recognize Salacioideae as a monophyletic group within Celastraceae. Nonetheless, some divergences exist for genera: in some cases, most species of the subfamily have been included in only two genera; in others, these genera have been subdivided. This study characterizes the leaf anatomy of 31 species of the subfamily Salacioideae as a contribution to identifying them through features that may also help distinguish among genera. Cross-sections of the median region of the leaf blade and of the petiole and dissociated and macerated epidermis were analyzed. Taxonomically relevant anatomical characters include the type of crystals in the parenchymatous tissue (monocrystals in Cheiloclinium and druses in other genera); the presence of laticifers in Cheiloclinium and Tontelea only; the variable form of the petiole vascular system among studied species; the type of stomata (cyclocytic with two concentric circles of subsidiary cells in P. dulcis; anomocytic in T. attenuata, T. fluminensis, and T. leptophylla; laterocytic in C. anomalum and C. hippocrateoides; and ciclocytic in the other species); the sinuosity of the anticlinal walls of the epidermal cells (sinuous in Cheiloclinium and Peritassa, except P. laevigata, and in S. arborea, S. insignis, S. mosenii, S. nemerosa, and S. opacifolia, and straight in all other studied species); the presence of crystalliferous idioblasts in the epidermis of P. dulcis, P. flaviflora, and P. mexiae; and the presence, form, and disposition of sclereids in the leaf blade, which is a highly variable character among the studied species.     

Comparative scanning and transmission electron microscopy studies of the ependyma of the central canal in the spinal cord of primates. I. Electron optical image of the ependyma in the central canal of the spinal cord of the callithrix monkey (Callithrix jacchus, Linné 1758)

The ependyma lining the central canal of the spinal cord of adult males and females monkey, Callithrix jacchus, was examined by scanning and transmission electron microscopy. The cross section of the lumen of the central canal are round, oval, or triangular. Light and dark ependymal cells, depending on the density of the cytoplasm, were found. The light ependymal cells are fewer than the dark cells. The ependyma cytoplasm contained numerous mitochondria, filamentous structures, one or more well-developed Golgi-complexes, vesicles of the smooth endoplasmic reticulum, ribosomes, lysosomes, multivesicular bodies, profiles of the rough endoplasmic reticulum, large osmophilic bodies, and microtubules. The nuclei of the ependyma cells usually have a simple, regular round or oval shape. They occupy a relatively large portion of the cell volume and lie in the central or mediobasal position. Some of the nuclei show deep invaginations into the karyoplasm. Most of the mitochondria occupy mainly the supranuclear portion of the apical cytoplasm. There are of the crista-typ. Ribosomes occur free in the cytoplasm, but some attached to the profiles of the rough endoplasmic reticulum or being arranged as polysomes. The filamentous structures are generally prominent cytoplasmic components and are distributed at the apical, lateral, or basal region of the ependymocytes. They are grouped into bundles and arranged in parallel arrays. Some of these bundles reach the plasmamembrane at the free lumina of the central canal, others take contact to the filamentous structures of the zonulae adherentes of the junctional complex below the free surface. The granular endoplasmic reticulum shows specializations. There profiles surrounding granular substances and widely distributed granulations in connection with the nuclear envelope. The functional significance of the deposition of these granulations is still unknown. The luminal surface of the ependymocytes bears many microvilli and cilia. The cilia are regularly arranged in cranio-caudal direction. Each cilium has the typical (9 + 2)-subfibres. The intercellular space at the surface of the ependymal layer shows a single zonula adherens or zonulae adherentes in the row. Tight junctions and gap junctions were not found in the material examined. Cell processes of liquor contacting neurons between adjacent ependyma cells, protruding into the lumen of the central canal, could be observed. The termination of these neurons contains accumulations of mitochondria in the central part, large amounts of vesicles, and small dense bodies. They have short microvilli and some stereocilia at the free surface.(ABSTRACT TRUNCATED AT 400 WORDS)     

Studies on the protein metabolism of Culex pipiens L.—III: A comparative analysis of the protein contents in the larval haemolymph of autogenous and anautogenous forms

The protein contents in the larval haemolymph of Culex pipiens (autogenous form) and Culex fatigans (anautogenous form) have been determined by paper electrophoresis. In both mosquito strains the electropherograms showed only one protein fraction which increased rapidly in its concentration during the later period of larval development. The fully grown larva of the anautogenous form was found to contain more proteins per unit volume blood than that of the autogenous form. On the other hand, the total blood concentration of the free ninhydrin-reacting components, as estimated by the method of paper chromatography, is higher in the autogenous form than in the anautogenous form. On the basis of data presented in this study, the relation of nutritional reserves to the phenomenon of autogenous egg production in mosquitoes is discussed.     

Eutrophication of the Salt Valley Reservoirs, 1968–73 III. The macroinvertebrate community: Its development,composition, and change in response to eutrophication

The macroinvertebrate communities of four flood control reservoirs in eastern Nebraska, differing in age and degree of eutrophy were investigated from Ekman grab samples. Generally, the longer a reservoir had been influenced by eutrophication the larger the standing crop in it. Chironomids, ceratopogonids, fingernail clams, and Hexagenia were important at various stages of eutrophication with Chironomus predominating in the most eutrophic reservoirs. Tubifex decreased with eutrophication as did Sphaerium simili while Sphaerium declive maintained its abundance and sometimes increased.The chironomids Chironomus, Coelotanypus, and Procladius, fingernail clams, and Tubifex were early colonizers in the newest reservoir and developed a total standing crop as large the first summer as in subsequent ones. However, its composition became more diverse with time. In one reservoir sampled year-round, the standing crop was largest in late fall or early winter and smallest during summer. The most accurate information on macro-invertebrate standing crops in lakes and reservoirs comes from data collected on a year-round basis.     

Diet of two selachians common to the Gulf of Gabes (Tunisia): Rhinobatos rhinobatos (Linnè, 1758) and Rhinobatos cemiculus (Geoffroy Sainte-Hilarie, 1817)

Rhinobatos rhinobatos and Rh. cemiculus are two digging species with a malacophagic and, accessorly ichthyophagic diet. Rh. rhinobatos' main prey is Hermione hystrix. Rh. cemiculus' one is Citharus macrolepidotus. This study points out that it exists few seasonal changes about the diet of these Selacians.     

Phytoplankton of a mountain lake (L’adové pleso,the Tatra Mountains,Slovakia): Seasonal development and first indications of a response to decreased acid deposition

A one-year study of the phytoplankton of remote mountain lake L’adové pleso (2057 m. a.s.l.), situated in the High Tatra Mountains, was carried out in 2000–2001. Seasonal development of the species structure and depth distribution of biomass, as well as chlorophyll-a concentrations, and chemical characteristics of the lake water were examined. The phytoplankton was made up of a low number of nanoplanktonic unicellular species, mainly flagellates from Cryptophyceae and Chrysophyceae. Plagioselmis lacustris, Cryptomonas cf. erosa and Ochromonas spp. were the most important with regards to both abundance and biomass. The phytoplankton showed a marked seasonal development. During most of the ice-covered period, abundances of phytoplankton remained very low. In regard to the vertical distribution, both species composition and total biomass were clearly stratified during most sampling dates. The amount of chlorophyll-a per unit biovolume varied considerably, and significantly higher values were found on sampling dates with complete or partial ice cover. Our data on pH and phytoplankton were compared with a previous study in 1990–1991 in order to evaluate possible changes associated with the decrease of acid deposition. The extent of episodic acidification of the lake water has diminished both in time and space, and lake water pH has slightly increased. We observed a shift in species composition, and an important increase of total phytoplankton abundance. This could be considered as a first sign of biological response to changing chemical conditions.     

Wood use in a medieval village: the contribution of wood charcoal analysis to the history of land use during the 13th and 14th centuries a.d. at Pobla d’Ifach, Calp, Alicante, Spain

Excavations on the Rock of Ifach, Alicante, Spain have revealed the remains of a medieval settlement that flourished between a.d. 1297 and 1359. Wood charcoal analysis combined with archaeological evidence and historical records allow an assessment of the local vegetation of the area during the medieval period, the obtaining and use of firewood and the commercial routes for supplying timber. Pinus halepensis and to a lesser degree various matorral taxa were used for fuel during the main occupation phases at the settlement. The resource exploitation network of the settlement expanded over the adjacent coastal area, with firewood obtained from pine woodlands there. The timbers used in the construction of the settlement were mainly from pines that originated nearby (P. halepensis) or which were transported by river from woodland areas to the north which were controlled by the Crown of Aragon (P. nigra/sylvestris, P. pinaster). The partial destruction of the village in a.d. 1359 and its gradual abandonment are reflected in changes observed in fuel supplying practices that then concentrated on the local matorral vegetation of the rock itself.