Distribution and abundance of European hake Merluccius merluccius (L.), eggs and larvae in the North East Atlantic waters in 1995 and 1998 in relation to hydrographic conditions

Plankton samples from surveys in 1995 and 1998 were analysedin order to study the spatial distribution of hake (Merlucciusmerluccius) eggs and larvae. The cruises covered an extensivearea from the south of the Bay of Biscay to the north-west ofIreland. This spatial distribution has been interpreted in relationto the direction and intensity of the dominant winds. An importantdecrease of eggs (69%) and larvae (27%) was observed from 1995to 1998. Hake showed continuous spawning from February to Julyin the area. The centroids of hake egg distribution indicateda northward displacement of the peak of spawning as the seasonprogresses. Spawning of hake was located close to the 200 mdepth isobath in the southern area (Bay of Biscay) and it spreadover the shelf in the area of the Celtic Sea. Eggs were mostabundant at 20 m depth temperatures between 12 and 12.5°C.The centroids of hake larvae distribution also showed a northwarddisplacement although not as strong as that of hake eggs. Thespatial distribution of hake larvae by size ranges showed importantdifferences between years: in 1995 it suggested inshore transportof larvae, from the spawning areas (close to the 200 m depthisobath) to nursery areas (closer to the coast) while in 1998it suggested offshore transport. This transport does not correspondwith the general wind regimes during those years. Thereforeit is concluded that the transport of the hake larvae to nurseryareas must be controlled by different hydrographic mechanismssuch as geostrophic currents in the Bay of Biscay and tidalcurrents in the northern areas.     

Glial Cell Composition and Ultrastructure of the Caudal Spinal Cord of Young and Adult Tuataras,Sphenodon punctatus

Research on the caudal spinal cord (SC) of three young and three adult tuataras (Sphenodon punctatus) has revealed that most of the glial cells were well differentiated as astrocytes and oligodendrocytes. The former type was not completely differentiated 3 months post-hatching, but was the main glial cell type at the age of 1 yr and in adulthood. Smaller numbers of oligodendrocytes were found in the white matter of adult animals than fibrous astrocytes. It was concluded that during growth, there is a progressive decrease in the dark, basophilic and electron-dense glioblasts, most of which develop as astrocytes.     

Structural investigation of Ceratozamia spinosa mucilage

The polysaccharide fraction from Ceratozamia spinosa appears to be made up mainly by a chemically homogeneous polysaccharide but with a wide range of molecular weight. By NMR and chemical degradative methods, it is shown to consist essentially of a backbone of alternate → 4)-β- -GlcpA-(1 → and → 2)-- -Manp-(1 → units. On the 4 position of the latter, β- -GlcpA residues are linked. End units of - -Ara f, β- -Xylp, - -Rhap, and - -3-OMe-Rhap are linked to C-3 and/or C-4 positions of β- -Glc pA residues.     

Long-Term Responses to Loss of Renal Mass: Pathophysiological Aspects: The Influence of Age on the Response to Renal Parenchymal Loss

The effect of age on compensatory hypertrophy and functional adaptation to loss of 75 percent of renal mass was studied in canine puppies. In one group of animals the surgery was done between 1-5 days after birth and in another group, at two months of age. All animals were studied six weeks later. Shamoperated littermates served as controls. The newborn puppies in the experimental group were able to grow and maintain homeostasis as well as their controls, whereas the older experimental animals grew poorly and had significantly higher levels of plasma creatinine than their sham-operated counterparts (p < .05). The increase in mass of the remaining kidney was twice as much in the newborn as in the older dogs. Functional adaptation, as expressed by GFR, was nearly complete in the young, but reached only about 45 percent of controls in the older age group (p<.005). The intrarenal blood flow distribution was similar for experimental and control animals in both groups studied. There were, however, marked differences in the pattern of single glomerular perfusion rates: whereas in the older dogs the increase was confined to the deeper nephrons, in the newborn an increase occurred in all zones of the kidney. These studies demonstrate that compensation for massive loss of renal tissue is complete when the injury is sustained in the immediate postnatal period but only partial when it occurs later on in life. A loss in the adaptive capacity of the superficial nephrons appears to account for this age-related difference.     

CHROMOSOMAL STUDIES OF SUBGENUS TRIDENTATAE OF ARTEMISIA: EVIDENCE FOR AUTOPOLYPLOIDY

The sagebrushes (subgenus Tridentatae of Artemisia—new combination presented in the text) are western North America's most widespread and populous shrub group. Chromosome counts from 120 populations confirm the base chromosome number at x = 9 with numerous 2n = 2x = 18 diploids and 2n = 4x = 36 tetraploids. Few higher polyploids are known, and aneuploidy and supernumerary chromosomes are rare. All 11 Tridentatae species are now known cytologically. All but the narrowly endemic A. argillosa are known from at least three locations: A. arbuscula (2n = 18, 36), A. bigelovii (2n = 18, 36), A. cana (2n = 18, 36), A. longiloba (2n = 18, 36), A. nova (2n = 18, 36), A. pygmaea (2n = 18, 36), A. rigida (2n = 18, 36), A. rothrockii (2n = 18, 36, 54, ca. 72), A. tridentata (2n = 18, 36, 54), and A. tripartita (2n = 18, 36). The chromosome number of A. argillosa, reported here for the first time, is 2n = 36. Chromosome numbers of eight subspecies also have been determined. The subgenus is characterized by autopolyploidy as indicated by morphologically indistinguishable 2x and 4x plants, a few mixed ploidy populations, consistent formation of IVs in 4x PMCs, a relatively uniform 2x karyotype, and a 4x karyotype, which is approximately twice the 2x one. Karyotypic differences, if they exist at all, are on a populational level rather than a systematic taxonomic level. The Tridentatae have apparently rapidly differentiated in situ in North America under the stimulus of recurring aridic cycles since late Tertiary or early Quaternary. They likely derive from more primitive circumboreal stock originating from the Eurasian homeland of Artemisia. The differentiation of myriad forms of Tridentatae was seemingly achieved through genic rather than genomic means. Karyotypic analysis supports a position within Tridentatae of A. rigida, A. bigelovii, and A. pygmaea.     

Cytogenetic survey of sixty-one patients with preleukemic syndrome including myeloproliferative and myelodysplastic diseases

The authors report on a cytogenetic survey of 61 patients with preleukemic syndrome (PLS). Of these, 41 had a myeloproliferative disease (MPD) and 20 a myelodysplastic syndrome (MDS). Clonal chromosome abnormalities appeared in 24 patients (39.3%) at disease onset. Such changes had a frequency of 26.8% in patients with MPD and 65% in those with MDS. The authors stress the usefulness of ethidium bromide high resolution techniques. They allow obtaining a larger number of metaphases and elongated chromosomes with higher banding resolution and could account for the frequent detection of chromosome changes in most groups of MDS patients in the present series. Moreover, they discuss the possible significance of some chromosome aberrations suggesting that patients with MPD may live longer than those with MDS because of their higher frequency of normal karyotypes.