Formin-like 1 (FMNL1) Is Regulated by N-terminal Myristoylation and Induces Polarized Membrane Blebbing

The formin protein formin-like 1 (FMNL1) is highly restrictedly expressed in hematopoietic lineage-derived cells and has been previously identified as a tumor-associated antigen. However, function and regulation of FMNL1 are not well defined. We have identified a novel splice variant (FMNL1γ) containing an intron retention at the C terminus affecting the diaphanous autoinhibitory domain (DAD). FMNL1γ is specifically located at the cell membrane and cortex in diverse cell lines. Similar localization of FMNL1 was observed for a mutant lacking the DAD domain (FMNL1ΔDAD), indicating that deregulation of autoinhibition is effective in FMNL1γ. Expression of both FMNL1γ and FMNL1ΔDAD induces polarized nonapoptotic blebbing that is dependent on N-terminal myristoylation of FMNL1 but independent of Src and ROCK activity. Thus, our results describe N-myristoylation as a regulative mechanism of FMNL1 responsible for membrane trafficking potentially involved in a diversity of polarized processes of hematopoietic lineage-derived cells.     

Morphological gradients in the starling basilar papilla

The starling cochlea was studied with TEM at four locations along the basilar papilla to investigate gradients in morphological features over the papilla's length and width. Hair cell shape changes continuously from neural to abneural and from basal to apical. Unlike the situation in mammals, there are no distinct populations of hair cells; the previously described types (tall hair cells and short hair cells) are merely extremes in a continuum. Contacts between THC are a normal feature. Except at the base of the papilla, SHC have very large cuticular plates, suggesting a micromechanical function for these cells. In contrast to the THC, the SHC normally completely lack afferent innervation; this indicates that their function is restricted to within the basilar papilla itself. © 1992 Wiley-Liss, Inc.     

Do pollen beetles need pollen? The effect of pollen on oviposition,survival, and development of a flower‐feeding herbivore

Abstract.  1. Pollen is considered to be an important dietary component for many species of flower-feeding herbivores. Its influence on oviposition site selection by the pollen beetle Meligethes aeneus , and on the development of its larvae was investigated.
2. The effects of pollen presence and absence on adult, egg, and larval incidence in the field, and on larval development in the laboratory were compared through the use of Synergy, a composite hybrid oilseed rape Brassica napus variety comprising male-fertile (with pollen) and male-sterile (without pollen) plants.
3. In the field, adult females were more abundant on male-fertile plants during flowering, and a greater proportion of male-fertile than male-sterile buds were accepted for oviposition. These data indicate a possible role of pollen in oviposition site selection by female pollen beetles.
4. The numbers of first instar larvae on the two plant lines did not differ; however, more second instars were found on male-fertile than on male-sterile flowers. This suggests a greater larval survival on male-fertile plants, possibly due to the more readily available food resources and better nutrition afforded by the presence of pollen.
5. Laboratory experiments confirmed that a diet which included pollen improved survival to adulthood and resulted in heavier pupae and adults; however, pollen was not obligatory for larval survival and development.
6. The pollen beetle, previously thought to be an obligate pollen feeder, is therefore more generalist in its requirements for development. These findings may relate to the nutritional and behavioural ecology of other flower-feeding herbivores.     

Plant responses to H2S and SO2 fumigation. I. Effects on growth, transpiration and sulfur content of spinach

Exposure of spinach (Spinacia oleracea L. cv. Monosa) to 0.25 μl l_?1 H₂S reduced the relative growth rate by 26, 47 and 60% at 15, 18 and 25°C, respectively. Shoot to root ratio decreased in plants fumigated at 18 and 25°C. Growth of spinach was not affected by a 2-week exposure to 0.10 or 0.25 μl l_?1 SO₂. Both H₂S and SO₂ fumigation increased the content of sulfhydryl compounds and sulfate. A 2-week exposure to 0.25 μl l_?1 H₂S resulted in an increase in sulfhydryl and sulfate content of 250 to 450% and 63 to 248% in the shoots, respectively, depending on growth temperature. Exposure to 0.15 and 0.30 μl l_?1 H₂S at 20°C for 2 weeks resulted in a 46% increase in sulfate content of the shoots at 0.30 μl l_?1 and no detectable increase at 0.15 μl l_?1 H₂S; the sulfate content of the roots increased by 195 and 145% at 0.15 and 0.30 μl l_?1 H₂S, respectively. Fumigation with 0.25 μl l_?1 SO₂ at 20°C for 2 weeks resulted in an increase in sulfhydryl content and sulfate content in the shoots of 285% and 300 to 1100%. H₂S fumigation during the 12 h light period or only during the dark period resulted in identical growth reduction and accumulation of sulfhydryl compounds; they were about 50 and 67% of those observed in continuously exposed plants. H₂S- and SO₂-exposed plants showed an increased transpiration rate, which was mainly caused by an increased dark-period transpiration. No effect of H₂S and SO₂ on the water uptake of the plants and the osmotic potential of the leaves was detected. Plants fumigated with 0.25 μl l_?1 H₂S for 2 weeks were smaller and differed morphologically from the control plants by slightly more abaxially curved leaf margins. Cross sections of the leaves showed smaller cells at the margins and smaller and fewer air spaces. The increased transpiration in the H₂S-exposed plants is discussed in relation to the observed morphological changes.     

Adventitions shoot formation on excised leaves of in vitro grown shoots of apple cultivars

Leaves taken from micropropagated shoots of several apple (Malus domestica Borkh.) cultivars were cultured in vitro on Linsmaier & Skoog (LS) medium or the rice anther culture medium of Chu et al. (N6) containing various concentrations of either benzyladenine (BA) or thidiazuron (TDZ) plus naphthaleneacetic acid (NAA). Of the TDZ concentrations tested, 10 M was most effective and it was equivalent to, or better than, 22 M BA for both the percentage of leaves regenerating shoots and number of shoots formed per regenerating leaf in almost every experiment. Lower concentrations of NAA (1.1 and 5.4 M) gave best results with both BA and TDZ. N6 medium gave consistently better results than LS. Lowering total salt concentration or total N concentration of LS to that of N6 did not improve the response nor did changing the NO₃:NH₄ ratio. The 3–4 leaves on the most distal part of the shoot were most responsive and tended to form the most adventitious shoots. Placing the leaf cultures in the dark for the first 2–3 weeks of the culture period produced the best results. Optimum results were obtained by culturing leaves from the distal part of the shoot in the dark for 2 weeks on N6 medium containing 10 M TDZ and 1.1 or 5.4 M NAA, then moving the cultures to 16 h daylight at a photon flux of 60 mol s^-1m^-2.     

Preferential expression of the maternally inherited X-linked phosphoglycerate kinase allele in human erythrocytes

Summary The stability of allelic gene expression of X-linked phosphoglycerate kinase was studied in seven carriers of a rare genetic variant named PGK München. The enzymatic activities in erythrocytes of five heterozygous females and three hemizygous males were determined repeatedly over a period of 10 years (1975–1984) and shown to remain constant. As the phosphoglycerate kinase activity is lower in cells expressing the PGK München allele, the ratio of the two cell types in all heterozygous females of the PGK München kindred could be calculated from the PGK activity and from the known allozyme activities in erythrocytes of homozygous wild type or hemizygous PGK München carriers. Since the maternal or paternal origin of both alleles is known from the pedigree, the quantitative expression of the maternally derived allozyme in heterozygous women could be determined. In heterozygous carriers the cell pool expressing the maternally inherited allele was significantly increased, independently, of the PGK allele linked to the maternal X chromosome (P<0.001). Our data show that inactivation of one of the two X chromosomes in human female erythropoietic stem cell precursors may be non-random, at least in the kindred and cell populations described here. The results are discussed in the context of random X chromosome inactivation (Lyon hypothesis).Dedicated to J.S., the senior of the family studied, on the occasion of her 80th birthday     

Molecular organisation of the genes involved in the production of F7(2) fimbriae, causing mannose-resistant haemagglutination, of a uropathogenic Escherichia coli 06:K2:H1:F7 strain

Summary The genes responsible for the formation of the F7₂ fimbriae of the uropathogenic E. coli strain AD110 (O6:K2:H1:F7) have been cloned on the recombinant plasmid pPIL110-35 (Van Die et al. 1983). The F7₂ fimbriae, like the F7₁ fimbriae of AD110, are responsible for mannose resistant haemagglutination (MRHA).The molecular organisation of the genes of pPIL110-35 involved in the expression of MRHA was studied by: (a) analysis of transposon and Tn5 insertion mutants. Mutations that cause an MRHA-deficient phenotype were located in discrete groups within an 11.5 kb restriction fragment of pPIL110-35, separated by insertion mutations that do not inactivate MRHA. (b) complementation experiments. Restriction fragments of pPIL110-35 subcloned in the vector pBR322 were tested for their ability to complement transposon insertion mutations in the corresponding regions of pPIL110-35. Five complementation groups were distinguished.Five genes (designated A-E) involved in the expression of MRHA can be distinguished by these results. The products of these genes were analysed in minicells. The results indicate that gene B codes for a 75 K dalton protein, gene C for a 23 K dalton protein and gene E for a 36 K dalton protein. No product of gene D was observed. Gene A probably codes for the 17 K dalton subunit polypeptide of the F7₂ fimbriae, as will be discussed.     

Investigation of cellobiohydrolase from trichoderma reesei by small angle X-ray scattering

Summary Trichoderma reesei was grown on sulfite pulp and the major cellobiohydrolase of the culture filtrate was purified to homogeneity. The distance distribution function p(r) measured by the small angle X-ray scattering technique indicates that the enzyme molecule has a rather unusual tadpole like shape with an isotropic head and a long tail. The maximum length is 18 nm and the largest diameter is 4.4 nm.