Mitotic chromosome biorientation in fission yeast is enhanced by dynein and a minus-end-directed, kinesin-like protein

Chromosome biorientation, the attachment of sister kinetochores to sister spindle poles, is vitally important for accurate chromosome segregation. We have studied this process by following the congression of pole-proximal kinetochores and their subsequent anaphase segregation in fission yeast cells that carry deletions in any or all of this organism's minus end-directed, microtubule-dependent motors: two related kinesin 14s (Pkl1p and Klp2p) and dynein. None of these deletions abolished biorientation, but fewer chromosomes segregated normally without Pkl1p, and to a lesser degree without dynein, than in wild-type cells. In the absence of Pkl1p, which normally localizes to the spindle and its poles, the checkpoint that monitors chromosome biorientation was defective, leading to frequent precocious anaphase. Ultrastructural analysis of mutant mitotic spindles suggests that Pkl1p contributes to error-free biorientation by promoting normal spindle pole organization, whereas dynein helps to anchor a focused bundle of spindle microtubules at the pole.     

The influence of ethylene perception on sex expression in melon (<Emphasis Type="Italic">Cucumis melo </Emphasis>L.) as assessed by expression of the mutant ethylene receptor, <Emphasis Type="Italic">At-etr1-1</Emphasis>, under the control of constitutive and floral targeted promoters

Sexual diversity expressed by Curcurbitaceae species is a primary example of developmental plasticity in plants. Ethylene, which promotes femaleness (carpel development), plays a key role in sex determination. We sought to determine the critical location for ethylene perception in developing floral primodia. The dominant negative Arabidopsis ethylene response mutant gene, etr1-1, was introduced into melon (Cucumis melo L.) plants under control of the constitutive cauliflower mosaic virus (CaMV) 35S promoter, or floral-targeted Apetela3 (AP3) and Crab’s Claw (CRC) promoters, which in Arabidopsis, promote expression in petal and stamen, and carpel and nectary primordia, respectively. Based on effects of exogenous ethylene, it was predicted that inhibition of ethylene perception by carpel primordia would inhibit carpel development. Constitutive expression of etr1-1 caused several phenotypes associated with ethylene insensitivity, verifying that etr1-1 inhibits ethylene perception in the heterologous melon system. Carpel-bearing bud production was essentially abolished in 35S::etr1-1 melons, providing direct demonstration of the requirement for ethylene perception for carpel development. CRC::etr1-1 plants, however, showed enhanced femaleness as manifested by earlier and increased number of carpel-bearing buds, and production of female (rather than bisexual) buds. Despite increased carpel-bearing bud formation, a greater proportion of the CRC::etr1-1 carpel-bearing buds aborted before anthesis. AP3::etr1-1 plants showed increased maleness by nearly exclusive staminate flower production, and poorly developed carpels in the rare bisexual flowers. These results indicate that ethylene perception by the stamen (or petal) primordia plays a critical role in promoting carpel development at the time of sex determination, while ethylene perception by the carpel is important for maturation of carpel-bearing flowers to anthesis.     

Fgf3 is required for dorsal patterning and morphogenesis of the inner ear epithelium

The inner ear, which contains sensory organs specialized for hearing and balance, develops from an ectodermal placode that invaginates lateral to hindbrain rhombomeres (r) 5-6 to form the otic vesicle. Under the influence of signals from intra- and extraotic sources, the vesicle is molecularly patterned and undergoes morphogenesis and cell-type differentiation to acquire its distinct functional compartments. We show in mouse that Fgf3, which is expressed in the hindbrain from otic induction through endolymphatic duct outgrowth, and in the prospective neurosensory domain of the otic epithelium as morphogenesis initiates, is required for both auditory and vestibular function. We provide new morphologic data on otic dysmorphogenesis in Fgf3 mutants, which show a range of malformations similar to those of Mafb (Kreisler), Hoxa1 and Gbx2 mutants, the most common phenotype being failure of endolymphatic duct and common crus formation, accompanied by epithelial dilatation and reduced cochlear coiling. The malformations have close parallels with those seen in hearing-impaired patients. The morphologic data, together with an analysis of changes in the molecular patterning of Fgf3 mutant otic vesicles, and comparisons with other mutations affecting otic morphogenesis, allow placement of Fgf3 between hindbrain-expressed Hoxa1 and Mafb, and otic vesicle-expressed Gbx2, in the genetic cascade initiated by WNT signaling that leads to dorsal otic patterning and endolymphatic duct formation. Finally, we show that Fgf3 prevents ventral expansion of r5-6 neurectodermal Wnt3a, serving to focus inductive WNT signals on the dorsal otic vesicle and highlighting a new example of cross-talk between the two signaling systems.     

UbiProt: a database of ubiquitylated proteins

Background  

Post-translational protein modification with ubiquitin, or ubiquitylation, is one of the hottest topics in a modern biology due to a dramatic impact on diverse metabolic pathways and involvement in pathogenesis of severe human diseases. A great number of eukaryotic proteins was found to be ubiquitylated. However, data about particular ubiquitylated proteins are rather disembodied.     

A study of water diffusion into a high-amylose starch blend: the effect of moisture content and temperature

The effect of moisture content and temperature on water diffusion into a modified high amylose (< or = 90%) maize thermoplastic starch blend was investigated. Gravimetric and magnetic resonance imaging (MRI) studies were conducted to elucidate the diffusion mechanism and diffusion coefficients for this system. The diffusion coefficient data demonstrated that the rate of water diffusion into this blend was significantly dependent upon temperature and moisture content. Water diffusion was faster at higher temperatures and generally for samples stored at higher relative humidity environments. It was revealed from the gravimetric data that water diffusion into this starch blend was Fickian; however, further analysis of the MRI images found that the water diffusion mechanism was exponentially dependent on the concentration. This result was determined by comparing experimental water concentration profiles to a theoretical model calculated using the implicit Crank-Nicolson finite difference method.     

Study of Interaction of the PARP Family DNA-Dependent Proteins with Nucleosomes Containing DNA Intermediates of the Initial Stages of BER Process

Biochemistry (Moscow) - Reaction of (ADP-ribosyl)ation catalyzed by DNA-dependent proteins of the poly(ADP-ribose)polymerase (PARP) family, PARP1, PARP2, and PARP3, comprises the cellular response...     

Cell Wall Galactofuranan of “Paenarthrobacter pyridinovorans” VKM Ac-1098D

Microbiology - The structure of the cell wall glycopolymer and the taxonomic position of the pyridine-degrading strain VKM Ac-1098D were established. By using chemical and NMR spectroscopic...     

Cell Wall Glycopolymers as a Diagnostic Trait of Arthrobacter crystallopoietes

Microbiology - The composition and structure of the cell wall glycopolymers from Arthrobacter crystallopoietes VKM Ac-1107T (family Micrococcaceae, phylum Actinobacteria), previously assigned to...