The Effect of Chilling of the Physiological and Simulated Apex of 2- and 3-leaf Plants of Pisum sativum L. cv. Alaska on Lateral Shoot Growth, C-14 IAA Movement and P-32 Accumulation

The apex of a 3-leaf pea plant was chilled in cold chambers maintained at 5–7°C. The lateral shoots 1 through 5 grew, and shoot 5 eventually dominated other lateral shoots. The apex when returned to the ambient temperature did not reimpose apical dominance. The growing lateral shoots competed with the stem apex. The apices of 2- and 3-leaf plants were chilled and P-32 distribution in these plants was studied in the entire plant, at various intervals of time. Phosphorus-32 accumulation followed the growth pattern of the plant. The lateral shoots accumulated P-32 activity and very little activity was accumulated by the apex. The dominating shoots 2 and 5 accumulated the maximum amount of activity in 2- and 3-leaf plants, respectively. Labeled-IAA moved basipetally through the stem when applied to the cut stump simulating the apex. By cold treatment the translocation of IAA was influenced more than its absorption. The plant seems to metabolize this compound in the later periods of application. The plant now becomes “insensitive” to auxin and the lateral shoots grow.     

Relationship between tektins and intermediate filament proteins: an immunological study

Affinity-purified antibodies raised against three flagellar tektins (tektin A, B, and C) from each of two sea urchin species (Lytechinus pictus and Strongylocentrotus purpuratus) were used to study the immunological relationship between tektins and intermediate filament proteins. By immunofluorescence microscopy, several antitektins revealed a staining of intermediate filament-like arrays in three vertebrate cell lines tested. Immunoelectron microscopy substantiated the cross reaction of antitektins with intermediate filaments. When the cells were treated with cytochalasin B, the arrangement of the filaments recognized by anti-(Lp)-tektin B was altered; the alteration observed is typical for keratin filaments. By immunoblot, it was found that anti-(Lp)-tektin B cross reacted with two isoforms or different proteins of approximately 54 kD with pIs of 6.1 and 6.2 in human carcinoma epithelia (HeLa) cells and with two isoforms or different proteins of approximately 55 kD with pIs of 6.1 and 6.3 in pig kidney epithelia (LLC-PK1) cells. Furthermore, when antitektin antibodies were affinity purified with the 54 kD HeLa keratin, these keratin-specific antibodies again restained the original tektins on immunoblots. From these observations, it can be concluded that tektins and keratins are to a certain extent immunologically related. To determine the degree of the immunological relationship, tektin filaments and purified intermediate filaments from HeLa cells were cleaved with alpha-chymotrypsin and examined by quantitative immunoblot analysis. On immunoblots of digested tektins from L. pictus, anti-(Lp)-tektin B recognized several cleavage products in the range of 20 kD to 46 kD. However, when immunoblots of digested intermediate filaments from HeLa cells were probed, the cross reaction of anti-(Lp)-tektin B with HeLa keratins was eliminated by more than 98% within 2 min, suggesting that tektins have epitopes in common with the end domains of certain keratins.     

B-cells of the synovial membrane. II. Differentiation during development of the synovial cavity in the mouse

Summary Study of pre- and postnatal development of the metatarsophalangeal joint of the mouse shows that the synovial cavity (SC) forms before any differentiation of the synovial mesenchyme. The primitive cleft results from degradation of a thin vascular mesenchymal layer in direct contact with the chondrogenic layers. Differentiation of the synovial membrane coincides with clarification of the SC (3rd to 6th day of postnatal life). When dilatation of the SC occurs (6th to 8th day), the two intimal cells types (A- and B-cells) are well identified. The B-cells already show typical features at day 6; their content of typical dense secretory vesicles is comparable to that of the adult B-cells at day 13. The specific secretory function of B-cells could be correlated with the particular structure of the intimal interstitial tissue and could account for the origin of some protein(s) of the synovial fluid.ERA 178 (Neuroendocrinologie Comparée) du CNRS et INSERM     

Membrane differentiations in spermatozoa of the squid,Loligo pealeii

Regional differences in the structure of the plasma membrane and acrosome membrane of squid spermatozoa were studied by freeze-fracture and thin section electron microscopy. In regions of close apposition the plasma membrane and acrosome membrane are adjoined to one another by regularly spaced linkages. These linkage sites, overlie a set of fibers located at the inner face of the acrosomal membrane. The acrosomal fibers terminate in a layer of granular material located at the base of the acrosome. Detergent treatment of sperm releases the fibers and granular material as an interconnected complex. Freeze-fracture replicas reveal a random arrangement of intramembranous particles in the plasma membrane over the sperm head and linear aggregates of intramembranous particles in the acrosomal membrane. Several regional differences in the structure of the flagellar plasma membrane are present. The thickness of the glycocalyx is progressively reduced distally along the flagellum. Freeze-fracture replicas show evenly spaced linear arrays of intramembranous particles which extend parallel t o the flagellar long axis. Examination of spermatozoa extracted to disrupt flagellar geometry suggest that the dense fiber-doublet microtubule complexes are attached to the plasma membrane. The possible functional role of these membrane differentiations and their relationship t o membrane structures in mammalian spermatozoa are discussed.     

Panmixia across elevation in thermally sensitive Andean dung beetles

Janzen's seasonality hypothesis predicts that organisms inhabiting environments with limited climatic variability will evolve a reduced thermal tolerance breadth compared with organisms experiencing greater climatic variability. In turn, narrow tolerance breadth may select against dispersal across strong temperature gradients, such as those found across elevation. This can result in narrow elevational ranges and generate a pattern of isolation by environment or neutral genetic differentiation correlated with environmental variables that are independent of geographic distance. We tested for signatures of isolation by environment across elevation using genome‐wide SNP data from five species of Andean dung beetles (subfamily Scarabaeinae) with well‐characterized, narrow thermal physiologies, and narrow elevational distributions. Contrary to our expectations, we found no evidence of population genetic structure associated with elevation and little signal of isolation by environment. Further, elevational ranges for four of five species appear to be at equilibrium and show no decay of genetic diversity at range limits. Taken together, these results suggest physiological constraints on dispersal may primarily operate outside of a stable realized niche and point to a lower bound on the spatial scale of local adaptation.     

Preliminary survey on putative insect vectors for Rubus stunt phytoplasmas

Phytoplasmas are cell wall‐less phytopathogenic bacteria which are associated with a disease in Rubus species known as Rubus stunt. Symptoms range from stunting, witches’ broom, small leaves, short internodes, enlarged sepals, phyllody and flower proliferation to fruit malformations. Phytoplasmas can be spread by vegetative propagation and by phloem‐feeding insect vectors. However, little is known about the spectrum and distribution of putative Rubus stunt insect vectors. In this study, a screening of putative insect vectors of Rubus stunt in raspberry plantations in southern and northern Germany was carried out during two successive years (2014 and 2015) with multiple sampling dates throughout the growing seasons. A total of 2,891 hemipteran insects were sorted, identified to family, genus or species level when possible, and a subset of 319 DNA samples containing a sum of 932 selected individuals representing all identified species, sampling locations and sampling dates were tested for phytoplasma DNA using qPCR. Altogether, eight DNA samples were positive for phytoplasma DNA, among them species from the genera Euscelidius, Macrosteles, Euscelis, Anaceratagalliaand Psammotettix. These data will form the basis for choosing and timing appropriate control measures against Rubus stunt and also for potential insect vector transmission experiments.     

Isolated cytoskeletons of human blood platelets: dark-field imaging of coiled and uncoiled microtubules

Detergent extraction of human blood platelets pre-treated with Taxol to stabilize microtubules allows isolation of marginal band (MB) cytoskeletons. We studied MB cytoskeleton structure using dark-field light microscopy and negative stain electron microscopy (EM). Dark-field illumination clearly demonstrated the "hoop" shape of MB cytoskeletons in unfixed suspensions where the microtubule coils had a mean diameter of 2.87 microns (+/- 0.18 micron, SD). Microtubules were uncoiled by brief exposure to trypsin (2 ng/micrograms protein) or by NaCl (154-600 mM) but not by DNase I, which removed approximately 40% of total actin, but had no effect on dark-field images of microtubule coils. As microtubules uncoiled, a single fiber emerged from the hoop and gradually lengthened as the brightness of the hoop diminished; these fibers correspond to the single microtubules seen by EM. Polypeptides of coiled and uncoiled MB cytoskeletons were analyzed by SDS-PAGE. When microtubules became uncoiled, no changes in the major components (alpha- and beta-tubulin, IEF-51K, or actin) were found. However, a number (greater than 10) of minor polypeptides, each less than 5% of total cytoskeletal protein and with an Mr ranging from 80,000- greater than 260,000, were decreased in "uncoiled" MB cytoskeletons. These results implicate one or more of these minor polypeptides in maintenance of hoop integrity. Dark-field light microscopy thus provides an approach toward investigating the mechanism(s) involved in maintaining the microtubule coil of the platelet marginal band.     

Enantioselective pharmacokinetics of lercanidipine in healthy volunteers

OBJECTIVE: The enantioselective kinetic disposition of lercanidipine, a dihydropyridine type of third-generation calcium antagonist, was investigated in six healthy male volunteers following a single 20 mg racemic oral dose. METHODS: Serial plasma samples were obtained from 0 to 24 h after drug administration. Lercanidipine enantiomers were analysed using a chiral LC-MS-MS method. RESULTS: The following differences (p < 0.05, Wilcoxon test) between (S) and (R) enantiomers were found (median): C(max) 2.071 ng mL(-1) versus 1.681 ng mL(-1); AUC(0-24)12.352 ng h mL(-1) versus 10.063 ng h mL(-1) and Cl/f 732.16 L h(-1) versus 1891.84 L h(-1). The AUC(0-infinity) values for (S)-LER were 1.21-fold higher than those for (R)-LER. CONCLUSION: The pharmacokinetics of LER was enantioselective in healthy volunteers following a single dose of 20 mg of the unlabeled racemic drug.     

Rib72, a conserved protein associated with the ribbon compartment of flagellar A-microtubules and potentially involved in the linkage between outer doublet microtubules

Ciliary and flagellar axonemes are basically composed of nine outer doublet microtubules and several functional components, e.g. dynein arms, radial spokes, and interdoublet links. Each A-tubule of the doublet contains a specialized "ribbon" of three protofilaments composed of tubulin and other proteins postulated to specify the three-dimensional arrangement of the various axonemal components. The interdoublet links hold the doublet microtubules together and limit their sliding during the flagellar beat. In this study on Chlamydomonas reinhardtii, we cloned a cDNA encoding a 71,985-Da polypeptide with three DM10 repeats, two C-terminal EF-hand motifs, and homologs extending to humans. This polypeptide, designated as Rib72, is a novel component of the ribbon compartment of flagellar microtubules. It remained associated with 9-fold arrays of doublet tubules following extraction under high and low ionic conditions, and anti-Rib72 antibodies revealed an approximately 96-nm periodicity along axonemes, consistent with Rib72 associating with interdoublet links. Following proteolysis- and ATP-dependent disintegration of axonemes, the rate of cleavage of Rib72 correlated closely with the rate of sliding disintegration. These observations identify a ribbon-associated protein that may function in the structural assembly of the axoneme and in the mechanism and regulation of ciliary and flagellar motility.