The discovery of the nature of ferredoxin in photosystems: A recollection

I describe here my recollection of the story of the discovery of the nature of ferredoxin in photosystems that began in 1965: this story involved the EPR measurements by a young physicist J.H.M. Thornley, using samples provided by J.F. Gibson and D. Hall, and in collaboration with F.R. Whatley.     

A novel TNNI2 mutation causes Freeman–Sheldon syndrome in a Chinese family with an affected adult with only facial contractures

Distal arthrogryposes (DAs), a clinically and genetically heterogeneous group of disorders characterized by congenital contractures with predominant involvement of the hands and feet, can be classified into at least 12 different forms. These autosomal dominant disorders are of variable expressivity and reduced penetrance. Mutations in sarcomeric protein genes, including troponin I2 (TNNI2), troponin T3 (TNNT3), tropomyosin 2 (TPM2), embryonic myosin heavy chain 3 (MYH3), and myosin binding protein C1 (MYBPC1), have been identified in distal arthrogryposis type 1 (DA1, MIM 108120), type 2B (DA2B, MIM 601680) and type 2A (DA2A)/Freeman–Sheldon syndrome (FSS, MIM 193700). However, mutations causing FSS have only been reported in MYH3. Herein we describe a Chinese DA family whose members meet classical strict criteria for FSS, as well as one member of the family who has isolated facial features consistent with FSS. No disease-causing mutation was found in MYH3. Segregation of microsatellite markers flanking the TNNI2 and TNNT3 genes at 11p15.5 was compatible with linkage. Subsequent sequencing of TNNI2 revealed a novel mutation, c.A493T (p.I165F), located in the C-terminal region, which is critical for proper protein function. This mutation was found to cosegregate with the FSS phenotype in this family, and assessment using SIFT and PolyPhen-2 predicted a damaging effect. To the best of our knowledge, we report the first TNNI2 mutation in classical FSS and describe an atypical adult FSS case with only facial contractures resulting from somatic mosaicism. We infer that DA1, DA2B and FSS represent a phenotypic continuum of the same disorder and provide further genetic evidence for this hypothesis.     

Antigen-initiated B lymphocyte differentiation. V. Electrophoretic separation of different subpopulations of AFC progenitors for unprimed IgM and memory IgG responses to the NIP determinant.

Spleen cells from CBA mice were separated by continuous, free-buffer film cell electrophoresis, and the capacity of cells in different fractions to mount an adoptive immune response specific for the NIP hapten determined. Experimental conditions were such that AFC progenitor B cells were measured, rather than helper or suppressor T cells. The IgM response of unprimed animals (a virgin or antigen inexperienced population) and the IgG response of long-term hapten-primed animals (a B memory cell population) were compared. The results indicated physical and biological heterogeneity in splenic B cells, with AFC progenitors for unprimed IgM and memory IgG responses being extensively separated.AFC progenitors for a primary IgM response in normal, germ-free and athymic mouse spleen, and bone marrow, separated into three distinct populations. Two of these were of much higher mobility than the typical splenic B cells and separated in the T cell zone. These cells produced a relatively early peak response of AFC after stimulation.AFC progenitors for a secondary IgG response were predominantly typical low-mobility B cells. Three regions of activity were separated, one overlapping part of the IgM progenitors. The slowest migrating activity peaks corresponded to the mobility of some recirculating B cells. These cells produced a more delayed AFC response after stimulation.AFC from the spleens of immunised mice separated as a single, broad, mediummobility peak distinct from most B cells and AFC progenitors. IgM and IgG (memory) AFC had similar electrophoretic characteristics.     

[3H]8-Hydroxy-2-(Di-n-Propylamino)Tetralin Binding to Pre- and Postsynaptic 5-Hydroxytryptamine Sites in Various Regions of the Rat Brain

The specific binding of [3H]8-hydroxy-2-(di-n-propylamino)tetralin ([ 3H]8-OH-DPAT) to 5-hydroxytryptamine (5-HT)-related sites was investigated in several regions of the rat brain. Marked differences were observed in the characteristics of binding to membranes from hippocampus, striatum, and cerebral cortex. Hippocampal sites exhibited the highest affinity (KD approximately 2 nM) followed by the cerebral cortex (KD approximately 6 nM) and the striatum (KD approximately 10 nM). Ascorbic acid inhibited specific [3H]8-OH-DPAT binding in all three regions but millimolar concentrations of Ca2+, Mg2+, and Mn2+ enhanced specific binding to hippocampal membranes, whereas only Mn2+ increased it in the cerebral cortex and all three cations inhibited specific binding to striatal membranes. Guanine nucleotides (0.1 mM GDP, GTP) inhibited binding to hippocampal and cortical membranes only. As intracerebral 5,7-dihydroxytryptamine markedly decreased [3H]8-OH-DPAT binding sites in the striatum, but not in the hippocampus, the striatal sites appear to be on serotoninergic afferent fibers. In contrast, in the hippocampus the sites appear to be on postsynaptic 5-HT target cells, as local injection of kainic acid decreased their density. Both types of sites appear to be present in the cerebral cortex. The postsynaptic hippocampal [3H]8-OH-DPAT binding sites are probably identical to the 5-HT1A subsites, but the relationship between the presynaptic binding sites and the presynaptic autoreceptors controlling 5-HT release deserves further investigation.     

Numerical technique of blood flow through catheterized arteries with overlapping stenosis

This study is concerned with the surgical technique for the injection of a catheter through arteries with overlapping stenosis in the presence of externally applied magnetic field and Hall currents influences. The nature of blood is analyzed mathematically by considering it as a micropolar fluid. The analysis is carried out for an artery with a mild stenosis. The governing equations with the corresponding boundary conditions solved numerically using Crank–Nicolson implicit finite difference scheme. The numerical technique give excellent agreement for axial velocity of the fluid, the circumferential microrotation, the wall shear stress distribution and the contour plots of stream lines. The obtained results show that the value of axial velocity is higher for a Newtonian fluid than that for a micropolar fluid model, the effect of suitable moving magnetic field (Hall currents influences) accelerates the speed of blood, the size of trapped bolus for the stream lines decrease if the spinning movement of the fluid molecules have considerable value regardless of small or large size of the fluid molecules and the flow of fluid is better with increasing the Hall current effect and the size of trapping bolus increase clearly by increasing the maximum height of stenosis where the fluid moves as a bulk.     

Endocrine events during pre-diapause and non-diapause larval-pupal development of the tobacco hornworm, Manduca sexta

The haemolymph ecdysteroid titre and in vitro capacities of prothoracic glands and corpora allata to synthesize ecdysone and juvenile hormone, respectively, during the last-larval instar of diapause-destined (short-day) and non-diapause-destined (long-day) Manduca sexta were investigated. In general, the ecdysteroid titres for both populations of larvae were the same and exhibited the two peaks characteristic of the haemolymph titre during this developmental stage in Manduca. The only difference in the titre occurred between day 7 plus 12 h and day 7 plus 20 h, when the short-day larval titre did not decrease as quickly as the long-day titre. The in vitro synthesis of ecdysone by prothoracic glands of short- and long-day larvae during the pharate pupal phase of the instar were also essentially the same. Activity fluctuated at times which would support the idea that ecdysone synthesis by the glands is a major contributing factor to the changes in the haemolymph ecdysteroid titre. There was one subtle difference in prothoracic gland activity between the two populations, occurring on day 7 plus 2 h. By day 7 plus 10 h, however, rates of ecdysone synthesis by the short- and long-day glands were comparable. This elevated activity of the short-day glands occurred just prior to the period the haemolymph ecdysteroid titre remained elevated in these larvae. The capacities of corpora allata to synthesize juvenile hormone I and III in vitro were not markedly different in long- and short-day last-instar larvae. At the time of prothoracicotropic hormone release in the early pupa, activity of corpora allata from short- and long-day reared animals was low and also essentially the same. There were a few differences in the levels of synthesis at isolated times, but they were not consistent for both homologues. Overall, there are no compelling differences in the fluctuations of ecdysteroids and juvenile hormones between diapause-destined and non-diapause-destined Manduca larvae. Since these hormones do not appear to play any obviously significant role in the induction of pupal diapause in this insect, the photoperiodic induction of diapause in Manduca appears to be a predominantly brain-centred phenomenon not involving endocrine effectors.     

Reactivity of amino acids in the azo coupling reaction: I. Dependence of their reactivity on pH

Azo coupling reactions of N-α-acetylhistidine, N-α-acetyltyrosine, and N-α-acetyllysine with p-methylbenzenediazonium ion were investigated as model reactions to obtain information on the relative reactivity of the histidine, tyrosine, and lysine moieties of protein, separated from structural effects. The azo coupling yields of the amino acids increased as the pH of the reaction medium was increased, indicating that the ractive species are the imidazole anion of histidine, the phenolate anion of tyrosine, and the neutral ε-amino group of lysine. It was calculated, based on percentage yields of the azo products, that the imidazole anion is more reactive than the phenolate anion and the ε-amino group, respectively.     

Regulative interactions between cells of wing discs from different dipteran species

The mechanism by which patterns are produced appears to be repeated in each segment of an animal, and it has been proposed that it may even have been conserved in evolution so that different species would have the same system of positional information. This idea has been tested by mixing cells of a defined fragment of the wing disc of Drosophila melanogaster with wing disc fragments of five other dipteran species to assay the ability of these disc fragments to stimulate intercalary regeneration of the D. melanogaster cells. The genetically marked (y; mwh) D. melanogaster fragment was mechanically mixed with wing discs or wing disc fragments of four drosophilids (D. melanogaster as a control, D. virilis, D. hydei, Zaprionus vittiger), of Musca domestica, and of Piophila casei. The mixed aggregates were cultured in vivo for 7 days, then metamorphosed in D. melanogaster larval hosts. The D. melanogaster fragments were only stimulated to regenerate when combined with complementary fragments from D. melanogaster or D. virilis wing discs. In the combination between D. melanogaster and D. hydei, the tissue formed integrated mosaic patterns, but no regeneration ensued. The one positive result (D. melanogaster mixed with D. virilis) shows that positional cues can be exchanged and correctly interpreted between cells of different species. The negative results do not prove that the mechanism for establishing patterns is different in the tested species, but may be due to incompatibilities that are not related to pattern formation.