In vitro clonal multiplication of the actinorhizal plant Comptonia peregrina

Micropropagation of the actinorhizal plant Comptonia peregrina of the Myricaceae was achieved successfully by the induction of root buds in excised root culture with cytokinin (1.0 M benzyladenine). Excised root segments with initiated root buds were subcultured in Woody Plant Medium (WPM) lacking growth regulators, developing extensive callus which subsequently gave rise to multiple adventitious buds. Shoot elongation was facilitated by transfer of calluses to more aerated conditions. Root initiation was induced on shoots by brief treatment with auxin (<1 M indolebutyric acid) and transfer to WPM for plantlet development. Controlled light and aeration in liquid medium were critical conditions for successful micropropagation.     

The genetics and expression of an esterase locus inAnopheles gambiae

The main polymorphic system of esterase isoenzymes in adults of the G3 laboratory strain ofAnopheles gambiae consists of two to five major bands of activity per individual. The bands are designated 5S, 5F, 13, 14, and 15. In genetic crosses, the genes which coded for the bands assorted as three codominant alleles, Est A, Est B, and Est C, at a single autosomal locus. Homozygotes for the Est C allele were significantly underrepresented among backcross progeny. The developmental pattern of esterase expression was examined. Esterase gene expression in embryos was first detectable between 2 and 12 hr after oviposition. The initiation or termination of expression of some of the bands corresponded to boundaries between developmental stages. Most of the esterase fractions were not specifically localized within the tissues tested, with the exception of a series of bands which were restricted largely to adult male testes.     

Effect of treatment with glutaraldehyde-fixed myelin basic protein-liposomes on active induction and passive transfer of experimental allergic encephalomyelitis in Lewis rats

Guinea pig myelin basic protein (MBP)-liposomes were prepared and fixed with 0.2% glutaraldehyde (GA). Lewis rats were treated with glutaraldehyde-fixed MBP-liposomes (MBP-L-GA) or with cytochrome-c-liposomes (CYC-L-GA), 7 days before and 7 days after challenge with MBP in CFA. Rats treated with MBP-L-GA, but not with CYC-L-GA, were very well protected against the clinical manifestations of EAE. The protection was better than that obtained after treatment with conventional MBP-liposomes (without glutaraldehyde). Furthermore, when grown in vitro for 72 hr in the presence of MBP, lymphocytes from rats treated with MBP-L-GA and challenged with MBP in CFA exhibited a marked decrease in their ability to transfer EAE to normal syngeneic recipients.     

Compartmentation of newly synthesized phosphatidylethanolamine in rat brain microsomes

Summary The compartmentation of the phosphatidylethanolamine newly synthesized in brain microsomesin vitro either by base exchange or net synthesis has been studied, using difluorodinitrobenzene as a chemical probe. The experimental results demonstrate that in rat brain microsomes the phosphatidylethanolamine molecules synthesized by base exchange and the bulk membrane lipid belong to different pools. Ca²⁺ bound to microsomes seems to be involved in the maintenance of the compartmentation of phosphatidylethanolamine. In the presence of Ca²⁺ the newly synthesized phosphatidylethanolamine molecules react with difluorodinitrobenzene as though they are organized in clusters. After biosynthesisin vivo orin vitro through the cytidine pathway, the compartmentation of the newly formed phosphatidylethanolamine appears less marked than after the synthesis through base exchange.     

Extracellular matrix components influence the survival of adult cardiac myocytes in vitro

Calcium-tolerant myocytes were isolated from adult rat hearts by collagenase perfusion and plated on various substrates in serum-free medium and their adhesion to various extracellular matrix (ECM) components was determined. The myocytes attached readily to dishes coated with collagen type IV (C-IV), laminin (LN), and to fetal bovine serum (FBS) in a manner dependent on the concentration of the components. Substantially fewer myocytes adhered to dishes coated with fibronectin (FN) or to uncoated plastic dishes. Cells adhered equally well to dishes coated with C-IV, LN and FBS within 1-4 h. However, when examined after 2 weeks in culture it was found that only C-IV and LN could support survival of the attached myocytes, and when cultured on C-IV or LN the myocytes were spread and had formed a dense monolayer. The actin filaments had at this time reorganized linearly along the long axis of the cell and the myocytes contracted spontaneously. Rabbit antibodies were raised against myocyte membranes and their ability to inhibit attachment to ECM components was studied. Purified IgG inhibited attachment to C-IV, while having only a minor effect on attachment to LN. These data are compatible with the presence of a specific cell surface component(s) that interacts with ECM substrates and influences cell shape and possibly thereby influences cellular functions.     

Hormonal regulation of fat esterification & oxidation in hepatocytes from fed rats: modulation by 3-mercaptopicolinate

3-Mercaptopicolinate, an inhibitor of phosphoenolpyruvate carboxykinase (PEPCK), decreased esterification of [1-14C] oleate and [1-14C] myristate in hepatocytes from fed rats. In the absence of 3-mercaptopicolinate, adrenaline, noradrenaline, vasopressin or angiotensin II increased esterification to triacylglycerol of [1-14C] oleate but not [1-14C] myristate. Cyclic AMP decreased esterification of both oleate and myristate. In the presence of 3-mercaptopicolinate, stimulation of oleate esterification by the catecholamines, vasopressin or angiotensin II was increased, and stimulatory effects of these hormones on myristate esterification were observed. Adrenaline, noradrenaline, vasopressin or angiotensin II increased 14CO2 production from both [1-14C] oleate and [1-14C] myristate but the degree of stimulation was similar in the absence or presence of 3-mercaptopicolinate. The results indicate a role for the catecholamines and angiotensin II in the regulation of liver fat metabolism and emphasize the potential importance of changes in activity of PEPCK as determinants of hepatic carbon flux.     

Relationships of the Col plasmids E2, E3, E4, E5, E6, and E7: Restriction mapping and colicin gene fusions

Thirteen ColE plasmids representing the E2-E7 types have been compared by restriction mapping. Over 80% of their restriction sites were found to be similarly positioned, indicating that these plasmids share a common structure. Three variants are ColE2-CA42 and ColE7-K317, both of which contain 1.8-kb DNA segments in place of a 2.5-kb segment common to the other plasmids, and ColE6-CT14, which has an additional 5.0-kb DNA segment compared to the other plasmids. The colicin (col), immunity (imm), and colicin release (hic) genes of these plasmids have been localized to regions corresponding to those known for ColE3-CA38 and ColE2-P9, with the imm and hic genes adjacent to the 3' end of the col gene. Active colicin is produced from hybrid col genes containing 5' and 3' ends from different E-type plasmids. The 3'-termini of the fused col genes specify the colicin type.     

Ketone-body metabolism after partial hepatectomy in the rat.

Fed or 24 h-starved rats were subjected to two-thirds partial hepatectomy or sham-operation and subsequently starved for 4, 14 or 24 h. Despite high plasma fatty acid concentrations, the partially hepatectomized rats failed to respond to post-operative starvation with increased blood and liver ketone-body concentrations or to maintain the high ketone-body concentrations associated with pre-operative starvation. Hypoglycaemia and hyperlactaemia were observed within 30 min of functional hepatectomy, but not partial hepatectomy, of 24 h-starved rats, and, even after a further 24 h starvation of partially hepatectomized rats, blood glucose concentrations were only slightly decreased. The results are discussed with reference to fat oxidation and gluconeogenesis in the liver remaining after partial hepatectomy.