481 research outputs found
Monolignolien kuljetusmekanismit solulimasta apoplastiseen tilaan puutuvissa soluissa
Ligniini on heti selluloosan jÀlkeen puiden toiseksi yleisin rakenteellinen biomolekyyli. Ligniini on tÀrkeÀ biopolymeeri sekÀ biologisesti ettÀ taloudellisesti. Ligniini antaa kasville fysikaalista kestÀvyyttÀ, erityisesti vettÀ kuljettavissa solukoissa, se toimii kasvin puolustuksessa patogeeneja vastaan fysikokemiallisena suojana. Taloudellisesti ligniini on sekÀ haitallinen ettÀ hyödyllinen yhdiste. Paperiteollisuudessa ligniinistÀ pyritÀÀn pÀÀsemÀÀn tarkasti eroon, koska hapettuessaan valon vaikutuksesta ligniinin absorbanssi muuttuu, ja kellastaa paperin. Energiatalouden kannalta ligniini on hyvin tÀrkeÀ molekyyli. Se sisÀltÀÀ paljon hiiltÀ ja sen polttaminen tuottaa nÀin ollen runsaasti energiaa. Ligniinin rakennetta kemiallisesti muokkaamalla siitÀ voidaan valmistaa monia hyödyllisiÀ yhdisteitÀ, kuten ravintolisiÀ, kuidunlÀhteitÀ, polttoainetta ja suoja-aineita. Ligniinin biosynteesin tunteminen on edellytys sen rakenteen muuttamiseen hyötykÀyttöön. Paperiteollisuuden kannalta erityisen tÀrkeÀÀ olisi yrittÀÀ vÀhentÀÀ ligniinin mÀÀrÀÀ sellupuussa, nÀin sÀÀstettÀisiin rahaa ja ympÀristöÀ huomattavasti, koska kemiallinen ja fysikaalinen ligniinin poistaminen paperimassasta on kallista ja ympÀristölle haitallista. Toisaalta energiapuun ligniinikoostumusta kannattaisi pikemminkin lisÀtÀ, nÀin puusta saatavaa energiamÀÀrÀÀ voidaan tilavuuteen nÀhden kasvattaa.
Ligniinin biosynteesi jakaantuu karkeasti ottaen kolmeen osaan: 1) ligniinin esiasteiden synteesiin 2) esiasteiden kuljetukseen solulimasta soluseinÀÀn 3) ligniinin polymerisaatioon soluseinĂ€ssĂ€. Ligniinin biosynteesin ensimmĂ€inen ja kolmas vaihe tunnetaan yksityiskohdiltaankin jo sangen hyvin. Sen sijaan toinen vaihe esiasteiden kuljetus on lĂ€hes tĂ€ysin tuntematon. TĂ€mĂ€ ei suinkaan tarkoita, ettĂ€ kuljetusvaihe olisi biosynteesin kannalta merkityksetön. PĂ€invastoin, se on hyvin tĂ€rkeĂ€ osa synteesiĂ€. Kuljetustapahtuma selvittĂ€minen voi hyvinkin lisĂ€tĂ€ tietĂ€mystĂ€mme myös ligniinin biosynteesin sÀÀtelystĂ€ ja ajoituksesta. Kuljetusmekanismia ei tunneta, mutta sille on esitetty kolme hypoteesi: 1) monolignolien suora diffuusio solukalvon lĂ€pi soluseinÀÀn, 2) Golgin laite âvĂ€litteinen kuljetus 3) ABC-transportterivĂ€litteinen kuljetus.
TÀmÀn työn tarkoituksena on tutkia Golgin laitteen ja ABC-transporttereiden osallisuutta monolignolien kuljetukseen. TÀssÀ työssÀ koniferiinia, mahdollista monolignolin kuljetus- ja varastomuotoa vastaan on valmistettu ja karakterisoitu vasta-aine, anti-koniferiini. Anti-koniferiinia kÀyttÀmÀllÀ on yritetty selvittÀÀ koniferiinin paikallistumista kuusen erilaistumisvaiheessa olevissa putkisoluissa. Koniferiinin sijaintia on myös selvitetty lituruohon juuressa ja kuusen A3/85-solukkoviljelmÀn soluissa. ABC-transporttereiden osallisuutta monolignolien kuljetukseen on selvitetty inhiboimalla monolignolien kuljetusta kuusen solukkoviljelmÀn soluissa, jotka ovat saaneet radioaktiivista glukoosia ja seuraamalla kuinka inhibiittori vaikuttaa solujen erittÀmien radioaktiivisten monolignoleiden eritysnopeuksiin.
Anti-koniferiinin havaittiin puhdistettuna tunnistavan sekÀ koniferiinin ettÀ koniferyylialkoholin. JÀlkimmÀisen tunnistus on kuitenkin heikompaa. Koniferiinin havaittiin paikallistuvan kolmevuotiaitten kuusten varressa puutuvien solujen soluseiniin. Lituruohossa koniferiini paikallistuu juuren huntuun. A3/85-soluissa koniferiini paikallistuu vakuolimaisiin rakenteisiin ja pistemÀisiin rakenteisiin solukalvon lÀheisyydestÀ. KÀytetyistÀ inhibiittoreista vanadaatin ei havaittu inhiboivan monolignoleiden kuljetusta, se pÀinvastoin kiihdyttÀÀ sitÀ. Reversin 121:stÀ saadut tulokset ovat tÀssÀ vaiheessa vielÀ ristiriitaisia
CLONING OF THE 1.4-kb mRNA SPECIES OF HUMAN COMPLEMENT FACTOR H REVEALS A NOVEL MEMBER OF THE SHORT CONSENSUS REPEAT FAMILY RELATED TO THE CARBOXY TERMINAL OF THE CLASSICAL 150-kDa MOLECULE
Three factor H mRNA species of 4.3 kb, 1.8 kb,
and 1.4 kb are constitutively expressed in human
liver. Having previously characterized full-length
cDNA clones derived from the 4.3-kb and 1.8-kb
factor mRNA, we report here the isolation and eucaryotic
expression of full-length cDNA clones coding
for the 1.4-kbm RNA species. The 1266-bp cDNA
codes for a polypeptide of 330 amino acids and
contains two polyadenylation signals and a short
poly(A)+tailT. he protein is composed of a leader
peptide followed by five short consensus repeat domains.
It shows a hybrid structure with the last
three domains being almost identical to the carboxy-
terminal of thcel assical 1 BO-kDa factor H molecule
and the two first domains representing unique
short consensus repeat structures. Eucaryotic
expression in COS7 cells revealed two polypeptides
derived from one cDNA clone that area lso found in
human serum. Differences between the cDcNloAn es
within the last three domains indicate two distinct,
possibly allelic sequences that, in addition, differ
from the authentic 150-kDa factor H sequence.
Southern blot results support the notion that the
4.3-kb factor H and the 1.4-kb factor H-related
mRNA are transcribed from two separate but highly
homologous genes.
Factor H, a glycoprotein of 150,00
A review of Characeae (Charophyta) in Murmansk Region (Russia) with notes on a new record of Chara virgata
Five species of Characeae are known in Murmansk Region from five biogeographic provinces (Lps, Lt, Lim, Ks, Lv). One of them, Chara strigosa A.Braun, is included in the Red Data Book of the Russian Federation. A new site for C. virgata KĂŒtz. is described from a rich fen in the province of Lim. This is the second record of the species in the Region. The new site is situated about 100 km NW of the previous one in a lake near the White Sea coast. The status of this species in the Regional Red Data Book should be âVulnerableâ
Effect of complement-protein-C3b density on the binding of complement factor H to surface-bound C3b
Relation between heart rate variability and spontaneous and induced ventricular arrhythmias in patients with coronary artery disease
AbstractObjectives. The aim of this study was to determine the relation between autonomic control of heart rate and the spontaneous occurrence and inducibility of ventricular arrhythmias in patients with coronary artery disease.Background. Low heart rate variability increases the risk of arrhythmic events. It is not known whether impaired autonomic heart rate control reflects alterations in functional factors that contribute to the initiation of spontaneous arrhythmias or whether it is the consequence of an anatomic substrate for reentrant tachyarrhythmias.Methods. Fifty-four patients with coronary artery disease with a history of sustained ventricular tachycardia (n = 25) or cardiac arrest (n = 29) were studied by 24-h ambulatory electrocardiographic recording and by programmed electrical stimulation. Heart rate variability was compared among the patients with and without spontaneous ventricular arrhythmias and with and without inducibility of sustained ventricular tachyarrhythmias.Results. Eight patients had a total of 21 episodes of sustained ventricular tachycardia on Holter recordings. Standard deviation of RR intervals and low frequency and very low frequency components of heart rate variability were significantly blunted in patients with sustained ventricular tachycardias compared with those without repetitive ventricular ectopic activity (p < 0.05, p < 0.01 and p < 0.05, respectively). However, no significant alterations were observed in heart rate variability before the onset of 21 episodes of sustained ventricular tachycardia. Heart rate variability did not differ between the patients with or without nonsustained episodes of ventricular tachycardia. In patients with frequent ventricular ectopic activity, low frequency and very low frequency power components were significantly blunted compared with those with infrequent ventricular ectopic activity (p < 0.01 and p < 0.001, respectively). Heart rate variability did not differ significantly between the patients with and without inducible sustained ventricular tachyarrhythmias.Conclusions. Impaired very low and low frequency oscillation of heart rate reflects susceptibility to the spontaneous occurrence of ventricular arrhythmias but may not reflect the instantaneous triggers for life-threatening arrhythmias or a specific marker of the arrhythmic substrate for ventricular tachyarrhythmias
Kinetics of GLUT4 Trafficking in Rat and Human Skeletal Muscle
OBJECTIVEâIn skeletal muscle, insulin stimulates glucose transport activity three- to fourfold, and a large part of this stimulation is associated with a net translocation of GLUT4 from an intracellular compartment to the cell surface. We examined the extent to which insulin or the AMP-activated protein kinase activator AICAR can lead to a stimulation of the exocytosis limb of the GLUT4 translocation pathway and thereby account for the net increase in glucose transport activity. RESEARCH DESIGN AND METHODSâUsing a biotinylated photoaffinity label, we tagged endogenous GLUT4 and studied the kinetics of exocytosis of the tagged protein in rat and human skeletal muscle in response to insulin or AICAR. Isolated ep-itrochlearis muscles were obtained from male Wistar rats. Vastus lateralis skeletal muscle strips were prepared from open muscle biopsies obtained from six healthy men (age 39 11 years an
Inventory of long and short term future needs of food chain users for future functions of internet
vokKVIKA
The transcription factor Prox1 is essential for satellite cell differentiation and muscle fibre-type regulation
The remarkable adaptive and regenerative capacity of skeletal muscle is regulated by several transcription factors and pathways. Here we show that the transcription factor Prox1 is an important regulator of myoblast differentiation and of slow muscle fibre type. In both rodent and human skeletal muscles Prox1 is specifically expressed in slow muscle fibres and in muscle stem cells called satellite cells. Prox1 activates the NFAT signalling pathway and is necessary and sufficient for the maintenance of the gene program of slow muscle fibre type. Using lineage-tracing we show that Prox1-positive satellite cells differentiate into muscle fibres. Furthermore, we provide evidence that Prox1 is a critical transcription factor for the differentiation of myoblasts via bi-directional crosstalk with Notch1. These results identify Prox1 as an essential transcription factor that regulates skeletal muscle phenotype and myoblast differentiation by interacting with the NFAT and Notch pathways.Peer reviewe
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