Der1, a novel protein specifically required for endoplasmic reticulum degradation in yeast.

The endoplasmic reticulum (ER) of the yeast Saccharomyces cerevisiae contains of proteolytic system able to selectively degrade misfolded lumenal secretory proteins. For examination of the components involved in this degradation process, mutants were isolated. They could be divided into four complementation groups. The mutations led to stabilization of two different substrates for this process. The mutant classes were called ''der'' for ''degradation in the ER''. DER1 was cloned by complementation of the der1-2 mutation. The DER1 gene codes for a novel, hydrophobic protein, that is localized to the ER. Deletion of DER1 abolished degradation of the substrate proteins. The function of the Der1 protein seems to be specifically required for the degradation process associated with the ER. The depletion of Der1 from cells causes neither detectable growth phenotypes nor a general accumulation of unfolded proteins in the ER. In DER1-deleted cells, a substrate protein for ER degradation is retained in the ER by the same mechanism which also retains lumenal ER residents. This suggests that DER1 acts in a process that directly removes protein from the folding environment of the ER.     

Stress and Age Related Spots with Immunoreactivity to Ubiquitin-Antibody at Protoplast Surfaces

Mesophyll protoplasts from primary leaves of 2, 3, and 4 weekold Viciafaba L. plants and from not expanded leaves of 2 weekold plants were incubated with rabbit anti-ubiquitin antibodyand FITC labeled goat anti-rabbit IgG. Dependent on age of theplant material, an increase in size and number of immunoreactivespots at protoplast surfaces were observed, when incubationswere performed after 16 h storage to allow protoplast to recover.A relationship between isolation stress and the intensity ofimmunolabeling was demonstrated for protoplasts from not expandedleaves. Furthermore, the surface of isolation stressed protoplastsshowed an increasing number of immunoreactive spots when plantswere previously exposed to water deficiency conditions for 1,2 or 4 days. Water deficiency conditions and isolation stressare therefore thought to induce ubiquitination of surface locatedproteins. A phenomenon, which seemed to be normally correlatedwith early events of senescence. (Received October 28, 1993; Accepted February 21, 1994)     

The effectiveness of flower strips and hedgerows on pest control,pollination services and crop yield: a quantitative synthesis

Floral plantings are promoted to foster ecological intensification of agriculture through provisioning of ecosystem services. However, a comprehensive assessment of the effectiveness of different floral plantings, their characteristics and consequences for crop yield is lacking. Here we quantified the impacts of flower strips and hedgerows on pest control (18 studies) and pollination services (17 studies) in adjacent crops in North America, Europe and New Zealand. Flower strips, but not hedgerows, enhanced pest control services in adjacent fields by 16% on average. However, effects on crop pollination and yield were more variable. Our synthesis identifies several important drivers of variability in effectiveness of plantings: pollination services declined exponentially with distance from plantings, and perennial and older flower strips with higher flowering plant diversity enhanced pollination more effectively. These findings provide promising pathways to optimise floral plantings to more effectively contribute to ecosystem service delivery and ecological intensification of agriculture in the future.     

The largest moss carpet transplant in Antarctica and its bryosphere cryptic biodiversity

Extremophiles - As part of the reconstruction of the Brazilian Antarctic Station on King George Island, three areas of moss carpet were transplanted to minimize the impact of the new facilities on...     

Thymosin β4 and Tissue Transglutaminase. Molecular Characterization of Cyclic Thymosin β4

Thymosin β₄ is the prototype of β-thymosins and is present in almost every mammalian cell. It is regarded to be the main intracellular G-actin sequestering peptide. Thymosin β₄ serves as a specific glutaminyl substrate for guinea pig transglutaminase. In the absence of an appropriate additional aminyl donor an ε-amino group of thymosin β₄ serves also as an aminyl substrate and an intramolecular bond is formed concomitantly NH₃ (17 Da) is lost. The molecular mass of the product is 4,949.6 Da. This is 16.3 Da less than the molecular mass of thymosin β₄ (4,965.9 Da). Digestion with endopeptidases and Edman degradation of the fragments identified the exact position of the ring forming isopeptide bond. In spite of 3 glutaminyl and 9 lysyl residues of thymosin β₄ only one isopeptide bond between Lys16 and Gln36 was formed (cyclic thymosin β₄). These two amino acid residues are conserved in all β-thymosins. Cyclic thymosin β₄ still forms a complex with G-actin albeit the stability of the complex is about one fiftieth of the stability of the thymosin β₄ × G-actin complex.     

AmSUT1, a sucrose transporter in collection and transport phloem of the putative symplastic phloem loader Alonsoa meridionalis

A sucrose (Suc) transporter cDNA has been cloned from Alonsoa meridionalis, a member of the Scrophulariaceae. This plant species has an open minor vein configuration and translocates mainly raffinose and stachyose in addition to Suc in the phloem (C. Knop, O. Voitsekhovskaja, G. Lohaus [2001] Planta 213: 80-91). These are typical properties of symplastic phloem loaders. For functional characterization, AmSUT1 cDNA was expressed in bakers' yeast (Saccharomyces cerevisiae). Substrate and inhibitor specificities, energy dependence, and Km value of the protein agree well with the properties measured for other Suc transporters of apoplastic phloem loaders. A polyclonal antiserum against the 17 N-terminal amino acids of the A. meridionalis Suc transporter AmSUT1 was used to determine the cellular localization of the AmSUT1 protein. Using fluorescence labeling on sections from A. meridionalis leaves and stems, AmSUT1 was localized exclusively in phloem cells. Further histological characterization identified these cells as companion cells and sieve elements. p-Chloromercuribenzenesulfonic acid affected the sugar exudation of cut leaves in such a way that the exudation rates of Suc and hexoses decreased, whereas those of raffinose and stachyose increased. The data presented indicate that phloem loading of Suc and retrieval of Suc in A. meridionalis are at least partly mediated by the activity of AmSUT1 in addition to symplastic phloem loading.     

Increased acetylcholine levels in skin biopsies of patients with atopic dermatitis

Recent experimental evidence indicates that non-neuronal acetylcholine is involved in the regulation of basic cell functions. Here we investigated the cholinergic system in the skin of healthy volunteers and patients with atopic dermatitis (AD). The synthesizing enzyme, choline-acetyltransferase (ChAT), was studied by anti-ChAT immunohistochemistry and enzyme assay. Skin biopsies taken from healthy volunteers and from AD patients were separated into the 2 mm superfical (epidermis and upper dermis) and 3 mm underlying portion (deeper dermis and subcutis). ChAT enzyme activity was detected in homogenized skin and subcutaneous fat (about 13 nmol/mg protein/h). ChAT immunoreactivity was expressed in keratinocytes, hair papilla, sebaceous and eccrine sweat glands, endothelial cells and mast cells. In healthy volunteers the superficial and underlying portion of skin biopsies contained 130 +/- 30 and 550 +/- 170 pmol/g acetylcholine (n = 12), respectively. In AD patients (n = 7) acetylcholine was increased 14-fold in the superficial and 3-fold in the underlying biopsy portion. The present study demonstrates the widespread expression of ChAT protein in the vast majority of human skin cells. Tissue levels of acetylcholine are greatly (14-fold) enhanced in the superficial 2 mm skin of AD patients.     

Significance of histiocytes on otherwise-normal cervical smears from postmenopausal women. A retrospective study of 108 cases

OBJECTIVE: To evaluate the significance of histiocytes on normal cervical smears from postmenopausal women and correlate them with endometrial pathology. STUDY DESIGN: Histiocytes were classified into three types. The clinical history was obtained from cytologic and surgical reports. RESULTS: Among 108 cervical smears, 13 had large, foamy histiocytes (type A), 88 had histiocytes resembling superficial endometrial stromal cells (type B), and 7 had variably sized histiocytes alone or in association with inflammatory or multinucleated cells (type C). Endometrial pathology was identified in 13 patients (12.0%): 4/13 with type A histiocytes (2 endometrial adenocarcinomas, 2 endometrial polyps), 8/88 with type B histiocytes (8 endometrial polyps) and 1/7 with type C histiocytes (endometrial polyp). Among 70 patients with no clinical indications for endometrial sampling except for the presence of histiocytes, 4 demonstrated endometrial pathology (all endometrial polyps). In contrast, endometrial pathology was identified in 9/38 with clinical indications for endometrial sampling. Among the 13 patients with endometrial pathology, 9 had a significant clinical history (sensitivity of 69.2%), and 4 had histiocytes as the only indication for endometrial biopsy (sensitivity of 30.8%). CONCLUSION: A significant clinical history is more predictive of endometrial pathology and outweighs the significance of histiocytes as an indication for endometrial biopsy.     

Yeast Cdk1 translocates to the plus end of cytoplasmic microtubules to regulate bud cortex interactions

The budding yeast spindle aligns along the mother- bud axis through interactions between cytoplasmic microtubules (CMs) and the cell cortex. Kar9, in complex with the EB1-related protein Bim1, mediates contacts of CMs with the cortex of the daughter cell, the bud. Here we established a novel series of events that target Kar9 to the bud cortex. First, Kar9 binds to spindle pole bodies (SPBs) in G(1) of the cell cycle. Secondly, in G(1)/S the yeast Cdk1, Cdc28, associates with SPBs and phosphorylates Kar9. Thirdly, Kar9 and Cdc28 then move from the SPB to the plus end of CMs directed towards the bud. This movement is dependent upon the microtubule motor protein Kip2. Cdc28 activity is required to concentrate Kar9 at the plus end of CMs and hence to establish contacts with the bud cortex. The Cdc28-regulated localization of Kar9 is therefore an integral part of the program that aligns spindles.