Immunogenicity and Antigenicity of Lymphoid Cells treated with Neuraminidase

SIALIC acid residues are the principal constituents on the surface of plasma membranes¹ and make the chief contribution to the negative charge of the cell surface². A number of functional alterations of the cell can be induced by removal of the sialic acid from the surface membrane by neuraminidase^3–6.     

A new genus of freshwater hoplonemertean from New Zealand

Potamonemertes percivali , a new freshwater hoplonemertean from the Selwyn River, New Zealand, is described. It is more closely related to the antipodean prosorhochmid supralittoral and terrestrial genera Acteonemertes and Geonemertes than to the only other freshwater hoplonemertean genus Prostoma,* but possesses a distinctive combination of characters which establish it as a new genus and species.     

A new species of Tetrastemma (Nemertea: Enopla: Monostiliferoidea) from Ria de Foz, north-western Spain, found living in the mantle cavity of the bivalve mollusc Scrobicularia plana

A new species of monostiliferoidean nemertean, Tetrastemmafozensis , from the mantle cavity of the bivalve mollusc Scrobicularia plana , in the Ría de Foz, north-western Spain, is described and illustrated. Other nemerteans from the mantle cavity of Scrobicularia collected in Poole Harbour, southern England, are provisionally identified as conspecific with the Ria de Foz material, but show certain anatomical differences whose taxonomic significance cannot at present be assessed.     

The genus Amphiporus Ehrenberg (Nemertea, Enopla, Monostiliferoidea)

The literature relating to the 145 nemertean species at one time or another included in the monostiliferoidean genus Amphiporus Ehrenberg, 1831 is reviewed. Because the designated type species, A. albicans , must be declared a nomen dubium , the status of the genus itself becomes uncertain. The 33 species which, at least in part, have previously been transferred to other genera are tabulated and the taxonomic status of the remaining forms is re-evaluated. Most are identified as nomina nuda, nomina dubia, species inquirendae or synonymous with other taxa, but one species, A. bimaculatus , is transferred to the genus Nipponnemertes .     

A study of genetic diversity in Populus nigra subsp. betulifolia in the Upper Severn area of the UK using AFLP markers

A survey of amplified fragment length polymorphism (AFLP) was conducted to examine genetic diversity in 146 individuals of British, native black poplar ( Populus nigra subsp. betulifolia ) and three individuals considered by collectors to be non- betulifolia poplars. Using two primer pairs, a total of 147 bands were detected of which 82 (56%) were polymorphic in at least one individual. Cluster analysis and principal coordinates analysis of the calculated similarity matrix revealed a low level of genetic diversity, although a loose clustering into five groups could be identified, one of which contained the non- betulifolia individuals. Examination of the spatial distribution of the other four groups (all betulifolia ) revealed a general correlation between geographic proximity and genetic similarity. On the basis of the polymorphism observed, it was possible to identify a small number of individual plants which exhibit maximum diversity and might therefore be suitable for inclusion in a replanting programme designed to maintain at least the existing low level of polymorphism observed within British black poplar.     

Herbicide toxicities in some Australian anurans and the effect of subacute dosages on temperature tolerance

Tadpoles of the anurans, Adelotus brevis, Limnodynastes peroni, and Bufo marinus were exposed to a range of concentrations of up to ten different herbicides. The Median Tolerance Limit (TL₅₀) was calculated for each toxicant from data obtained by static bioassay. Some adult frogs (Litoria ewingi and Limnodynastes tasmaniensis) were subjected to greater concentrations of several of the toxicants. Toxicity varied greatly among the tadpoles exposed to various toxicants with fenoprop being the most toxic chemical tested, while no differences were observed in behaviour or activity between the exposed and control adult frogs. A significant reduction occurred in the thermal tolerance of one to two week old A. brevis exposed to subacute dosages of amitrole-T, picloram, and 2,2-DPA.     

Gonyaulax monilata: Population Growth and Development of Toxicity in Cultures

SYNOPSIS. The development of three 8-liter and four 12-liter cultures of the photosynthetic dinoflagellate Gonyaulax monilata was followed for 4 months. Weekly estimates were made of population levels of this chain-forming flagellate, along with incidence of cells in chains and toxicity to fish. Guppies ( Lebistes reticulatus ) were used to assay toxicity. Populations reached a peak when cultures were 3–5 weeks old, declined during weeks 6–10, and tended to stabilize thereafter thru the 17th (final week). The percentage of cells in chains was related to the slope of the population curve; rapidly increasing populations had the highest proportion of long chains, suggesting that incidence of chains is an index of the growth phase in G. monilata. Peak toxicity was not reached until culture populations had been steadily declining for a month, indicating that most toxin is released by autolysis. The reproducibility of culture population and toxicity levels recommend the methods used for future studies.