Comparison of the 13C-n.m.r. spectra of gangliosides GM1 with those of GM1-oligosaccharide and asialo-GM1

The ¹³C-n.m.r. spectra of asialo-G_M1 and G_M1-oligosaccharide are completely assigned and compared to those previously found for intact G_M1 and for the series G_M4, G_M3, G_M2, G_M1, G_D1a, G_D1b, and G_T1b. Removal of the ceramide residue from G_M1 liberated a free, reducing aldehyde group, which was reflected in a doubling of the ¹³C-n.m.r. signals assignable to the d-glucose residue because of α,β equilibrium. The spectrum of asialo-G_M1 lacks the resonances from the sialic acid residue, as expected; in addition, several resonances from the neutral gangliotetraglycosyl residue shifted to different field positions after removal of sialic acid from G_M1. These resonances include that of C-4 of the inner β-d-galactosyl residue, and C-1 of the 2-acetamido-2-deoxy-d-galactosyl residue that is near the site of attachment of the sialosyl residue. The differences between the chemical shifts of the carbon resonances of oligomeric and monomeric saccharides, termed linkage shifts, provide a quantitative assignment aid. They are ～ $\text{1}\text{3}$ of those for residues linked to sialic acid than those for residues linked to the neutral hexose chain. Correlations among linkage shifts for pairs of glycosidically-linked carbon atoms for asialo-G_M1 and G_M1-oligosaccharide were compared with those for the series of gangliosides G_M4 to G_T1b, and differences are noted for resonances for carbon atoms near the sialic acid residue. The spectrum of ganglioside G_M1b, a positional isomer of G_M1 whose ¹³C-n.m.r. spectrum has not yet been observed, is predicted.     

Ontogeny of B-lymphocyte function. XIV. Maturation of the capacity of B cells to re-express surface immunoglobulin after treatment with anti-immunoglobulin

The maturation of the ability of the B-cell population to re-express surface immunoglobulin (sIg) after its removal by treatment with rabbit anti-mouse immunoglobulin (RAMIg) was studied in LAF1, C57BL/6, and C57L mice. As demonstrated by previous workers, the B-cell population from immature mice failed to re-express sIg after treatment with RAMIg. We have shown that the age at which the B-cell population acquires the capacity to re-express sIg is different in different strains and that the order in which the B-cell population of the different strains acquires the capacity to re-express sIg is different from the order in which their B-cell populations acquire the capacity to produce high-affinity antibodies. This suggests that these represent distinct differentiation events in the development of the B-cell population. In all of the strains studied the maturation of the capacity to re-express sIg occurred in two steps. After the first maturation step the B-cell population was able to re-express sIg after treatment with RAMIg for 1 hr but did not re-express sIg after treatment with RAMIg for 24 hr. After the second maturation step the B-cell population could re-express sIg even after 24 hr treatment with RAMIg. It has been suggested by previous workers that the inability of the immature B-cell population to re-express sIg could represent one of the mechanisms responsible for the development of B-cell self-tolerance. It is suggested here that the existence of a period during which cells become tolerant only upon prolonged exposure to antigen could protect the developing B cells from becoming unresponsive to transiently experienced foreign antigens but still permit them to become tolerant to self antigens which are continuously present.     

Loss and resynthesis of a developmentally regulated membrane protein (gp80) during dedifferentiation and redifferentiation in Dictyostelium

When developing cultures of Dictyostelium discoideum are disaggregated and resuspended in nutrient medium, they lose the capacity to rapidly reaggregate after 90 min, in a rapid and synchronous step referred to as the "erasure event." They then proceed to lose remaining developmentally acquired functions in a program of dedifferentiation culuminating with the loss of EDTA-resistant cohesion roughly 5 hr later. Immediately following the erasure event, cells can be stimulated to reenter the developmental program even though they still possess a number of developmentally acquired functions. These cells therefore appear to undergo dedifferentiation and redifferentiation simultaneously (D. R. Soll and L. H. Mitchell, 1982, Dev. Biol. 91, 183-190). In this report, we have employed an antiserum made against a developmentally acquired membrane glycoprotein, gp80, to examine whether gp80 is lost during dedifferentiation and whether it is either reutilized or resynthesized during redifferentiation. Results are presented which demonstrate that (1) when 9-hr developing cells are disaggregated and resuspended in nutrient medium, gp80 continues to accumulate for several hours after the erasure event, then is lost at roughly the same time as EDTA-resistant cohesion; (2) when cells are stimulated to reenter the developmental program immediately after the erasure event, both gp80 and EDTA-resistant cohesion are still lost according to the program of dedifferentiation, but are then reacquired soon afterwards according to the program of redifferentiation; (3) during redifferentiation, cells do not reutilize gp80 which had been synthesized during initial development; rather they synthesize gp80 de novo; and (4) developing cells of a dedifferentiation-defective variant, HI4, when disaggregated and resuspended in nutrient medium, retain gp80, EDTA-resistant cohesion, and the capacity to rapidly reinitiate aggregation for at least 12 hr. This last result indicates that the loss of gp80 is regulated by the dedifferentiation process and is not an independent response to disaggregation or the reintroduction of nutrients. Together, these results reinforce the conclusion that dedifferentiation and redifferentiation can function independently and simultaneously in the same cells.     

长江中游鱼类寄生棘头虫区系的研究

经过3年10次调查,剖检湖北省宜都、黄冈两处江段所产72种鱼类,共计766尾。收集棘头虫10种,其中包括2新种和1新组合,即蛇鮈新棘吻虫(新种)Neoechinorhynchus saurogobi sp.nov.,长江丽棘虫(新种)Brentisentis yangtzensis sp.nov.(Illiosontidae),鲤丽棘虫(新组合)B.cyprini comb.nov.。对长江中游鱼类寄生棘头虫区系的特点进行了分析和探讨。     

Growth, dry weight partitioning and wood properties of Pinus radiata D. Don after 2 years of CO2 enrichment

Abstract Advanced selections (families 20010 and 20062) of P. radiata D. Don were exposed to either 340 or 660 μmol CO₂ mol ¹ for 2 years to establish if growth responses to high CO₂ would persist during the development of woody tissues. The experiment was carried out in glasshouses and some of the trees at each CO₂ concentration were subjected to phosphorus deficiency and to periodic drought. CO₂ enrichment increased whole-plant dry matter production irrespective of water availability, but only when phosphorus supply was adequate. The greatest increase occurred during the exponential period of growth and appeared to be tied to increased rates of photosynthesis, which caused accelerated production of leaf area. The increase in whole-plant dry matter production was similar for both families; however, family 20010 partitioned larger amounts of dry weight to the trunks than family 20062. which favoured the roots and branches. Wood density was generally increased by elevated CO₂ and for family 20010 this increase was due to thickening of the tracheid walls. Tracheid length was similar at both CO₂ levels but differed between families. These results suggest that, as the atmospheric CO₂ concentration rises, field-grown P. radiata should produce more dry weight at sites where phosphorus is not acutely deficient, even where drought limits growth; however, increases in wood production are likely only for genotypes which continue to partition at least the same proportion of dry weight to wood in the trunk.     

Shape analysis of two sympatric coral species: Implications for taxonomy and evolution

Fourier shape analysis of Pleurodictyum americanum and P. dividua , favositid tabulate corals, from the Middle Devonian Hamilton Group of New York State, indicates that colony growth form is variable within species between environments, but that the range of variability in growth form is static through time. Pleurpdictyum dividua displays a columnar morphotype; however, P. dividua and P. americanum cannot be discriminated from one another based on colony shape alone. A major prediction of the punctuated equilibrium model of evolution is morphological stasis throughout the duration of a species. Harmonic means of assemblages of P. americanum show no persistent temporal trends. The range of harmonic means present among the oldest assemblages (Centerfield Limestone) are comparable to those among the youngest assemblages (Windom Shale) and to those in the intervening intervals. Character stasis in colony growth form lasted throughout a 2.5-3.5 my interval. In tabulate corals, where reproductive modes such as fragmentation have not been demonstrated, growth form may be useful in interpreting ancient environments. In addition, the tempo of evolution of growth form can be analyzed when sufficient morphological data are available from a wide distribution of environments. Thus, Fourier shape analysis of growth form provides a powerful tool for paleontologists to interpret the ecology and evolution of colonial marine animals.     

斜胸叶蝉属一新种（同翅目：叶蝉总科：耳叶蝉科）

本文记述耳叶蝉科斜胸叶蝉属一新种:黄缘斜胸叶蝉Epiclinata flavomarinata sp.nov.。标本采自我国西藏。文中描述了新种的外部形态及雄性外生殖器构造特征,并与近似种进行比较,附有主要特征图。模式标本保存于中国科学院动物研究所。     

条鳅亚科鱼类一新属新种

本文描述了云南省条鳅亚科鱼类一新属和一新种。根据形态特征并结合区系间的相互关系,探讨了属的分类地位。     

四川青城山优食蚜蝇属二新种记述（双翅目：食蚜蝇科）

本文记述四川青城山优食蚜蝇属Eupeodes 2新种:青优食蚜蝇Eupeodes (Eupeodes) qingchengshanensis和小优食蚜蝇Eupeodes(Eupeodes)parvus,均属于Eupeodes s.str.,亚属。模式标本保存于上海农学院昆虫标本室。     

内蒙古草蛉研究Ⅱ.五新种及二新记录种(脉翅目:草蛉科)

内蒙古地处我国北部边疆,全境以高原为主,西部为戈壁沙漠,东部为宽阔草原,绝大多数地区属于温带大陆性气候;动物地理区划属于古北区中亚细亚区的内蒙河西干草原区。该区现已知草蛉3属16种(包括本文所记述的5新种和2新记录种),其分布特点是以狭义的草蛉属Chrysopa为主,而且以广布于华北地区的叶色草蛉Chrysopaphyllochroma Wesmeal为代表种,新种的模式标本分别保存在中国科学院动物研究所及北京农业大学昆虫标本室。