Induction of water-stress proteins in cyanobacteria exposed to matric- or osmotic-water stress

Abstract: Specific stress polypeptides were detected in three drought-resistant cyanobacteria ( Phormidium autumnale , LPP₄ and Chroococcidiopsis sp.) subjected to matric- and osmotic-water stress. Drought stress caused the induction of at least 2–3 new polypeptides of apparent molecular masses of 30 kDa and 40–45 kDa. The polypeptide of 30 kDa was located in the thylakoid membranes, and the 45-kDa polypeptide in the cytoplasm. When these cyanobacteria were exposed to salt stress polypeptides of similar size appeared.     

The activity of 2,5-oligoadenylate synthetase, an interferon-induced enzyme, is coupled to the differentiation state of mouse condylar cartilage

The enzyme 2,5-oligoadenylate synthetase (2-5A synthetase) is associated with the interferon system, with special reference to the differentiation process of various cell types. The present study investigated whether 2-5A synthetase is also involved in the differentiation of neocartilage in perinatal mice. The cartilage of the mandibular condyle, a secondary type of cartilage, develops relatively late in prenatal life; and consequently it was possible to obtain a relatively embryonic cartilage at a developmental stage that could be manipulated enzymatically, in order to separate and thereby obtain its undifferentiated, proliferative portion along with its more mature fraction. Immunohistochemical studies using antibodies against type I and type II collagen and cartilage-specific proteoglycans could have determined the differentiation status of various portions of the developing condyle. However, the above methodology lacks the necessary precision and accuracy to indicate subtle changes in cellular differentiation. It became evident that the activity of 2-5A synthetase was indeed different in cellular compartments that were at different stages of differentiation. In the neonatal condyle the highest level of activity was encountered in proliferating and as yet undifferentiated prechondrocytes, whereas fully differentiated chondrocytes showed a marked decrease in the activity of this enzyme.     

Attachment to the substrate by soft coral fragments: desmocyte development, structure, and function

Abstract. Pieces cut from colonies of the soft coral Dendronephthya hemprichi exhibited rapid and effective attachment to hard surfaces. Attachment involved development of root-like processes (RLPs), which appeared at the basal part of the fragment 4 days after its removal from the colony. The fine structural changes and cascade of cellular events occurring in the RLP before and after attachment were studied using SEM, TEM, and LM. The epidermis of the RLPs is actively involved in the attachment process and several distinct phases are documented: appearance of numerous oval vesicles, extrusion of these vesicles resulting in the formation of an outer layer composed of extracellular organic matrix and organellar debris, which functions as an adhesive device leading to initial attachment. The latter phase was followed by the formation of desmocytes, which develop in the RLP epidermis and function as anchoring devices, mediating the firm attachment of the fragment to the substrate. This is the first evidence among anthozoans that desmocytes play an active role in anchoring tissue to substrate and thus extends the range of functions exhibited by desmocytes among anthozoans.     

Human tumor cells, modified by a novel pressure/crosslinking methodology, promote autologous lymphocyte proliferation and modulate cytokine secretion

 Hydrostatic pressure (P) combined with membrane protein crosslinking (CL) by adenosine dialdehyde (AdA) can render tumor cells immunogenic. We have recently shown that PCL treatment of murine tumor cells augmented the presentation of MHC-restricted tumor-associated antigens and enhanced cell-mediated immunity. In cancer patients inoculated with autologous PCL-modified tumor cells, a significant delayed-type hypersensitivity response was elicited. Since the balance between cell-mediated immunity and humoral immunity is reciprocally controlled by immunoregulatory cytokines, we have examined the proliferative response and cytokine secretion pattern in cultures of human peripheral blood mononuclear cells (PBMC) stimulated by autologous PCL-modified and unmodified tumor cells. These tumor cells were obtained from freshly resected tumor tissue of 16 patients with colon (8), lung (4) and renal (4) carcinomas. The results demonstrated that PCL-modified tumor cells promoted an increase in PBMC proliferation in 5 out of 8 (63%), 1 out of 4 (25%) and 4 out of 4 (100%) colon, lung and renal cell carcinomas. Fourteen of the above cultures were also analyzed for the secretion of interleukin-10 and interferon-γ. Overall, a substantial decrease in IL-10 secretion was detected in 9 out of 14 (64%) cultures while a reciprocal increase in interferon-γ secretion was noted in 8 out of 14 (57%) cultures. Our results confirmed that PCL-modified human tumor cells of different etiologies can modulate the pattern of cytokines released from stimulated autologous lymphocytes. Such a procedure could prove valuable in the production of autologous tumor vaccines. Received: 8 January 1998 / Accepted: 9 April 1998