Intercalation and Pattern Regulation in Hydroids

Several topics and concepts in developmental biology, such as induction of secondary axes (as in amphibians), the rules of distal transformation (valid, e.g., for insect and vertebrate limbs), and the rule one piece regenerates, the other one duplicates (valid also for imaginal discs) originally emerged from pioneering studies in hydroids. In addition, one finds phenomena of intercalation, i.e., the insertion of intervening parts when tissues of distant origin are confronted with each other. However, since not only short-range but also long-range interactions contribute to pattern regulation, one observes more regulative flexibility as compared to insect systems.     

Purification and characterization of a membrane-bound protein kinase from spinach thylakoids

A protein kinase was isolated from spinach thylakoid membranes by solubilization with octyl glucoside and cholate. The enzyme was purified to apparent homogeneity by ammonium sulfate precipitation, gel filtration, and sucrose density centrifugation, followed by affinity chromatography on either Affi-Gel blue (yielding denatured enzyme) or on histone cross-linked to Sepharose (yielding active enzyme). Electrophoresis on denaturing polyacrylamide gels, followed by staining with silver, revealed the kinase as a single band corresponding to an apparent molecular mass of 64 kDa. The active enzyme underwent autophosphorylation and could be detected by autoradiography following incubation with [gamma-32P]ATP and Mg2+ ion. The specific phosphotransferase activity of purified kinase was approximately 30 nmol of phosphate min-1 (mg protein)-1 with lysine-rich histone (III-S or V-S) as substrate; casein was phosphorylated at approximately 30% of this rate. The physiological substrate for the kinase is presumed to be light-harvesting chlorophyll a/b protein complex. In solubilized form, this was phosphorylated at approximately 10% of the rate observed with histone III-S as substrate, or 10-100 times slower than the estimated rate of phosphorylation of the light-harvesting complex in situ. Possible reasons for this shortfall are considered. The kinase is proposed as the principal effector of thylakoid protein phosphorylation and associated State transition phenomena.     

Conus-like structure in the eye of the deep-sea teleost Radiicephalus elongatus (Pisces,Teleostei)

Summary A conus-like structure, the hyaloid conus, located on the optic nerve head of the mesopelagic deep-sea teleost Radiicephalus elongatus is described. The hyaloid conus consists of a tapering sheath of unpigmented, vascularized connective tissue enveloping the proximal part of the hyaloid artery which proceeds from the optic nerve head through the vitreous body to the ventrally located falciform process and lens muscles. The hyaloid artery passes through the hyaloid conus without giving off any branches. The conus vessels encircling the hyaloid artery receive arterial blood from the choroid via small arteries and are drained to the choroid by a single vein. The hyaloid conus is compared with the lacertilian conus papillaris. The function of the hyaloid conus is unknown. Because of its small dimensions relative to those of the eyeball and its few capillaries, it is unlikely that the hyaloid conus is a supplemental nutritive device for the retina.     

Electrophoretic evaluation of the taxonomic status of two species of sea anemone

Puerto Rican populations of two species of sea anemones (Bunodosoma cavernata and B. granulifera) which had previously been considered one were assayed electrophoretically for enzymes encoded by 12 loci. The two species shared no common allozymes at 6 of the 12 loci. Genetic distance and identity values based on these allozymes were computed for the Puerto Rican populations and for B. cavernata from Florida and B. granulifera from Panama. The Puerto Rican populations of both species had much higher genetic identities for their geographically distant conspecifics than for each other. These results indicate that the two species are reproductively isolated and should be considered as separate valid species. Average heterozygosities are presented which are the first published for coelenterate species.     

Structure—activity relationships in the mutagenicity of quinone methides of 7-hydroxyflavylium salts for Salmonella typhimurium

Several synthetic 7-hydroxyflavylium salts related to apigeninidin, a natural 3-deoxyanthocyanidin, have been studied in the Ames mutagenicity test using strain TA1537 of Salmonella typhimurium. Under the neutral pH conditions of the test, these flavylium salts are deprotonated through ionization of the C7-OH (pK_a′ = 4.2–4.4) to form quinone methides. Only the quinone methides of 4-methyl-7-hydroxyflavylium chloride and 4′-methoxy-4-methyl-7-hydroxy-flavylium chloride showed mutagenicity. Responses of 4–8 times the background were observed at the higher doses (1000 μg/plate), both with and without metabolic activation. It was concluded that the induction of frameshift mutagenicity by this group of compounds is caused by those quinone methides that have non-ionic, stable polycyclic structures at neutral pH.     

Mechanism of action of ryanodine on cardiac sarcoplasmic reticulum

Ryanodine was found to initially inhibit calcium uptake by cardiac sarcoplasmic reticulum. This initial depression was followed by a later marked stimulation of calcium uptake. These effects were noted when calcium uptake was measured in the presence or absence of oxalate. The requirement for preincubation with ryanodine was highly dependent on ryanodine concentration and temperature. The mechanism of action of ryanodine clearly was not an effect on oxalate entry or calcium oxalate precipitation because the effects were also observed in the absence of oxalate. Ryanodine also had no effect on passive calcium efflux from actively loaded vesicles. Because ryanodine had no effect on Ca2+-ATPase activity under defined conditions of an ATP-regenerating system and no calcium gradient, we suggest ryanodine does not change the stoichiometry of the pump. Our results are consistent with the hypothesis that ryanodine closes a calcium channel in a subpopulation of the vesicles.     

The position of the epistatic S locus in the halothane linkage group in pigs

The linkage of the Phi, Pgd, Po2, S, H and halothane sensitivity loci was followed in a Belgian Landrace family, heterozygous for these systems over 6 generations. Recombination next to the S locus occurred mainly in pigs belonging to this particular family. From this investigation the position of the S locus is proved to be outwith the Phi-Pgd region, next to Phi . Therefore the gene sequence S - Phi - Hal -H- Po2 -Pgd is proposed. Higher recombination rates were observed in the female parental line of the multiheterozygous family when compared to the male parental line. Additional data from animals, unrelated to this strain, confirm the evidence of close linkage of the S system to the nearest marker loci.     

Content of red blood-cell sialic acid in BW 35 blood donors. Relation to magnesium concentration and pyruvate kinase activity

Previous studies have shown that the concentration of red blood cell (RBC) magnesium is significantly lower in subjects carrying an HLA-BW 35 antigen (p less than 0.001) than in non-carriers. As this finding might be related to modifications of the RBC membrane sialoglycoconjugates, RBC sialic acid was comparatively determined in BW 35+ and BW 35- subjects. Pyruvate-kinase activity mean RBC volume, and reticulocyte count have also been determined in order to estimate whether some significant variations in the level of these age markers could be detected between the HLA BW 35+ and BW 35- subjects. A significant negative correlation between sialic acid and RBC magnesium concentrations was observed for the whole population tested (n 57, p less than 0.005), 61% of the BW 35+ and only 25% of the BW 35- individuals having sialic acid values above, and magnesium values below the overall mean (p less than 0.01). The variance of mean RBC volume was also larger for the BW 35+ group. Other determinations did not show any significant variations, suggesting that the results are not related to RBC age.