Absence of generalized immunosuppression in C57BL/6J mice implanted with Lewis T241 fibrosarcoma or Lewis lung carcinoma

Summary The immune status of C57BL/6J mice implanted with Lewis T241 fibrosarcoma or Lewis lung (LL) carcinoma was investigated on days 14 and 28 after implantation. Splenic lymphocyte responses were assessed in mitogen (Con A, LPS) mixed lymphocyte culture (MLC), natural killer (NK), graft-vs-host (GVH), and interleukin production assays. Except for NK-cell cytotoxicity, all other immunologic parameters were either comparable to those in medium-implanted controls or augmented. NK cytotoxicity was reduced in both tumor-bearing groups on day 28. The provision of NK potentiation therapy (-interferon, polyinosinic: polycytidylic acid) to T241 mice under various treatment conditions did not have any significant effect on lung metastasis or survival.The results of this study do not support the thesis that T241-or LL-bearing C57BL/6J mice are generally immunosuppressed. Indeed, when immune functions were assessed on the basis of total splenic activity, each of the measured immunologic parameters was substantially greater in animals with tumors than without. Further it seems improbable, considering the magnitude of the NK-cell defect in T241 mice on days 14 and 28 after implantation and the absence of a therapeutic response to NK-cell stimulants, that NK-cell cytotoxicity is intrinsically associated with resistance to tumor progression in this model.     

Functional morphology of the branchial basket of ascidia paratropa (Tunicata,Ascidiacea)

Summary The filtering surface of the branchial basket of Ascidia paratropa (Huntsman, 1912) consists of two adjacent and connected sheets. The stigmatal surface is loosely folded. The secondary gill screen, composed of ciliated longitudinal vessels with primary and secondary papillae, is connected to the stigmatal surface on the inside of the branchial basket. Continuous mucus secretion results in a net with elastic and adhesive properties, and a pore size of less than 0.5 m in its longest dimension. Net production cannot be interrupted by external mechanical stimuli. The net is usually supported by and transported across the secondary screen, forming a filtering surface that parallels the undulations of the stigmatal surface; however, localized muscular activity of the dorsal laminar fold and longitudinal vessels are also involved in mucous net transport. Squirts occur more frequently than in many species. At these times the net is transported as a flat sheet, independent of the secondary screen. Squiring does not interrupt continuous feeding activity.     

The activation process of Arabidopsis thaliana A1 gene encoding the translation elongation factor EF-1α is conserved among angiosperms

In Arabidopsis thaliana, the activation process of the A1 EF-1 gene depends on several elements. Using the GUS reporter gene, transient expression experiments have shown that mutations of upstream cis-acting elements of the A1 promoter, or the deletion of an intron located within the 5 non-coding region, similarly affect expression in dicot or monocot protoplasts. The results reported here strongly suggest that this 5 intron is properly spliced in Zea mays. We show that two trans-acting factors, specifically interacting with an upstream activating sequence (the TEF 1 box), are present in nuclear extracts prepared from A. thaliana, Brassica rapa, Nicotiana tabacum and Z. mays. In addition, a DNA sequence homologous to the TEF 1 box, found at approximately the same location within a Lycopersicon esculentum EF-1 promoter, interacts with the same trans-acting factors. Homologies found between the A. thaliana and L. esculentum TEF 1 box sequences have allowed us to define mutations of this upstream element which affect the interaction with the corresponding trans-acting factors. These results support the notion that the activation processes of A. thaliana EF-1 genes have been conserved among angiosperms and provide interesting data on the functional structure of the TEF 1 box.     

The carbohydrases of Bacillus stearothermophilus NCIB 11412 and NCIB 10814

Summary Two strains (NCIB 11412 and NCIB 10814) of the thermophilic organism Bacillus stearothermophilus were found to produce complex carbohydrase systems. The enzyme activities in each system include -amylase as the major component, maltase, pullulanase, a minor amylase and cyclodextrinase. The latter three activities are produced in low yield in both strains. A crude enzyme preparation from each strain possessed maltogenic properties on hydrolysis of soluble starch. Following rigorous purification procedures, the purified major -amylase from either strain did not produce maltose as a major end-product of starch hydrolysis. However, a partially purified mixture of pullulanase, minor amylase and cyclodextrinase activities from NCIB 11412 and NCIB 10814 produced 56.4% and 62.0% maltose, respectively, from soluble starch.     

Physiological responses underlying the timing of vernal activities in insects

Temperate zone insect species have evolved three general strategies for synchronizing the end of hibernation with the return of favorable conditions. Recent eco-physiological studies of insect dormancy and development indicate that the prevailing concepts of the adaptations regulating hibernation and the resumption of spring activity, need revision. In particular, experimental evidence shows that despite implications in the term, dormancy is a dynamic state; the organism, by constantly monitoring the constantly-changing environmental parameters, is kept in phase with the seasons at its particular locality. Furthermore, the insect's ability to respond to environmental factors generally changes as the season progresses. Therefore, the construction of realistic predictive models of insect seasonality should be based on investigations of natural populations undergoing hibernation in the field, combined with ecologically and physiologically meaningful laboratory studies.Presented at the Seventh International Biometeorological Congress, 17–23 August 1975, College Park, Maryland, USA.