Complex relationship of body mass index with mortality in patients with critical limb ischemia undergoing endovascular treatment.

OBJECTIVE: To investigate the relationship between body mass index (BMI) and long-term outcomes of patients with CLI after endovascular treatment (EVT). DESIGN: Retrospective multicenter study. SUBJECTS: 1088 consecutive patients (1306 limbs, mean age 72 ± 10 years) with CLI who underwent EVT for isolated infrapopliteal artery lesions were evaluated. These subjects were identified in the J-BEAT III registry. METHODS: The patients were divided into groups based on BMI <18.5 kg/m2 (underweight, n = 188; 219 limbs), 18.5 to 24.9 kg/m2 (normal weight, n = 718; 868 limbs), and >25.0 kg/m2 (overweight/obese, n = 182; 219 limbs). The endpoints were overall survival and freedom from major adverse limb events (MALE). RESULTS: The median follow up period was 1.5 years (range: 1 month-8.7 years). The 3 year overall survival rates were 33.3%, 61.2%, and 69.8% in underweight, normal, and overweight/obese patients, respectively. The survival rate was significantly lower in underweight patients and significantly higher in overweight/obese patients compared with patients of normal weight (both p < .0001). The 3 year rates of freedom from MALE did not differ significantly among the three groups (36.4%, 45.4%, and 52.3%, respectively, p = .32). Age, BMI <18.5 kg/m2, heart failure, aortic valve stenosis, renal failure, triglyceride levels, serum albumin <3.0 g/dL, anticoagulant treatment, non-ambulatory status, and Rutherford 6 classification all were significantly associated with overall survival. CONCLUSIONS: BMI has a complex correlation with mortality in patients with CLI after EVT for isolated infrapopliteal artery lesions. Underweight patients with CLI have an extremely poor prognosis. Such patients have many other factors associated with mortality, but low BMI was identified as an independent predictor of a poor prognosis in patients with CLI. Similarly, normal weight patients had a small but significant increase in mortality compared with overweight/obese patients.

Impact of control measures including decolonization and hand hygiene for orthopaedic surgical site infection caused by MRSA at a Japanese tertiary-care hospital.

BACKGROUND: Meticillin-resistant Staphylococcus aureus (MRSA) is the most common pathogen in orthopaedic surgical site infections (SSIs). However, few studies have investigated the transmission process of orthopaedic MRSA SSI. AIM: To investigate the transmission process of orthopaedic MRSA SSI using epidemiological and molecular analyses and to determine a method to prevent MRSA SSI in nosocomial orthopaedic surgery. METHODS: Active MRSA surveillance, preoperative decolonization and contact precautions for MRSA-positive cases was performed at our institution. Changes in epidemic strains were evaluated and the possibility of transmission from patients in an orthopaedic ward of a Japanese tertiary-care hospital was assessed by genotyping stored MRSA strains. In addition, data on the prevalence of MRSA SSI, MRSA colonization, and use of an alcohol antiseptic agent (mL/patient-days) during 2005-2022 were retrospectively assessed. FINDINGS: SCCmec type II strain in the SSI group decreased over time, associated with fewer outbreaks. Even during a period of high infection rates, no cases of transmission-induced SSI from nasal MRSA carriers were identified. The infection rate correlated negatively with the use of an alcohol antiseptic agent (r = -0.82; P < 0.0001). Two cases among five nasal carriers developed MRSA SSI caused by strains different from those related to nasal colonization. CONCLUSION: The infection control measures for transmission from the hospital reservoirs including strict adherence to hand hygiene and decolonization of carriers is likely to be important for the prevention of orthopaedic MRSA SSI. However, the need for contact precautions for decolonized nasal carriers might be low.

Genetic decrease in fatty acid unsaturation of phosphatidylglycerol increased photoinhibition of photosystem I at low temperature in tobacco leaves.

Leaves of transgenic tobacco plants with decreased levels of fatty acid unsaturation in phosphatidylglycerol (PG) exhibited a slightly lower level of the steady state oxidation of the photosystem I (PSI) reaction center P700 (P700(+)) than wild-type plants. The PSI photochemistry of wild-type plants was only marginally affected by high light treatments. Surprisingly, all plants of transgenic lines exhibited much higher susceptibility to photoinhibition of PSI than wild-type plants. This was accompanied by a 2.5-fold faster re-reduction rate of P700(+) in the dark, indicating a higher capacity for cyclic electron flow around PSI in high light treated transgenic leaves. This was associated with a much higher intersystem electron pool size suggesting over-reduction of the PQ pool in tobacco transgenic lines with altered PG unsaturation compared to wild-type plants. The physiological role of PG unsaturation in PSI down-regulation and modulation of the capacity of PSI-dependent cyclic electron flows and distribution of excitation light energy in tobacco plants under photoinhibitory conditions at low temperatures is discussed. This article is part of a Special Issue entitled: Photosynthesis Research for Sustainability: from Natural to Artificial.

Isolation and characterization of an ether-type polyurethane-degrading micro-organism and analysis of degradation mechanism by Alternaria sp.

AIMS: To degrade ether-type polyurethane (ether-PUR), ether-PUR-degrading micro-organism was isolated. Moreover, ether-PUR-degrading mechanisms were analysed using model compounds of ether-PUR. METHODS AND RESULTS: A fungus designated as strain PURDK2, capable of changing the configuration of ether-PUR, has been isolated. This isolated fungus was identified as Alternaria sp. Using a scanning electron microscope, the grid structure of ether-PUR was shown to be melted and disrupted by the fungus. The degradation of ether-PUR by the fungus was analysed, and the ether-PUR was degraded by the fungus by about 27.5%. To analyse the urethane-bond degradation by the fungus, a degraded product of ethylphenylcarbamate was analysed using GC/MS. Aniline and ethanol were detected by degradation with the supernatant, indicating that the fungus secreted urethane-bond-degrading enzyme(s). PURDK2 also degraded urea bonds when diphenylmethane-4,4'-dibutylurea was used as a substrate. CONCLUSIONS: The enzyme(s) from PURDK2 degraded urethane and urea bonds to convert the high molecular weight structure of ether-PUR to small molecules; and then the fungus seems to use the small molecules as an energy source. SIGNIFICANCE AND IMPACT OF THE STUDY: Ether-PUR-degrading fungus, strain PURDK2, was isolated, and the urethane- and urea-bonds-degrading enzymes from strain PURDK2 could contribute to the material recycling of ether-PUR.

[Radiosurgery in trigeminal neuralgia: long-term results and influence of operative nuances]. / La radiochirurgie dans le traitement de la névralgie trigéminale : résultats à long terme et influence des nuances techniques.

Stereotactic radiosurgery is an alternative to conventional surgery for the treatment of trigeminal neuralgia. To better define the safety of radiosurgery and optimal technical choices, we reviewed our patient records and the literature. A total of 334 patients presenting with trigeminal neuralgia were treated between December 1992 and September 2005. A minimum of 1 year of follow-up was available for 262 patients. The mean age was 68 years (range: 30-90); 128 patients were male and 134 female. A neurovascular conflict was clearly visualized on MRI in 167 patients. Twenty-one had a past history of multiple sclerosis and 110 had already received conventional surgical treatment for trigeminal neuralgia. The intervention consisted of gamma knife radiosurgery (GKS) to the retrogasserian cisternal portion of the Vth cranial nerve. The median maximal dose used was 85Gy (range: 70-90). Actuarial curves show a plateau at 5 years for both the risk of hypoesthesia and recurrence. At 5 years, 58% of the patients remain pain-free and 83% have no trigeminal nerve disturbance. The median delay for pain cessation was 15 days. The initial pain-relief rate was 89%. None of the complications reported for the other techniques were observed. Patient selection (typical versus atypical, age, past surgery, multiple sclerosis) and details of operative technique (maximum dose, volume of nerve treated, target location, etc.) had a major influence on the probability of pain relief and toxicity risk. The details of operative technique are turning out to have a major influence on the clinical results. In our experience, high-dose (80-90Gy) retrogasserian (7-8mm from the brainstem) GKS provides the patient with a better chance of long-term pain relief and a lower risk of trigeminal nerve functional disturbance. GKS applied to the cisternal anterior trigeminal nerve using high doses provided safe and effective treatment for trigeminal neuralgia over the long term.

Low-temperature resistance of higher plants is significantly enhanced by a nonspecific cyanobacterial desaturase.

A broad-specificity delta 9 desaturase gene was cloned from the cyanobacterium Anacystis nidulans. The enzyme introduces a cis-double bond at the delta 9 position of both 16 and 18 carbon saturated fatty acids linked to many kinds of membrane lipids. The gene was stably introduced into tobacco plants under transcriptional control of the cauliflower mosaic virus 35S promoter, and the enzyme was targeted into plastids by the transit peptide of the pea RuBisCO small subunit. The transgenic plants had a highly reduced level of saturated fatty acid content in most membrane lipids and exhibited a significant increase in chilling resistance.

[Preoperative morphological assessments of congenital heart disease by multidetector computed tomography].

Preoperative morphological assessments and anatomical delineation are keys to treatment of adult patients with congenital heart disease. We report on 2 cases where morphological assessments by multidetector-row computed tomography (MDCT) were useful. Case 1. A 33-year-old male was diagnosed with atrial septal defect (ASD) complicated by mitral regurgitation (MR), tricuspid regurgitation (TR), and severe pulmonary hypertension. In establishing the diagnosis, we carefully examined and confirmed that there was no possibility of ostium primum defect or other complicating malformations. MDCT was useful for demonstrating the location and morphology of the defect, anatomical relation to the tricuspid ring and the presence or absence of complicating malformations. Case 2. A 61-year-old female was diagnosed with double-chambered right ventricle with an intraventricular pressure gradient of 80 mmHg. MDCT extensively and clearly delineated the position and shape of abnormal muscle bundles and the morphology of complicating ventricular septal defect (VSD). MDCT was also useful in the determination of specific surgical procedures and the quick understanding of the anatomy during surgery, and even in postoperative assessments of therapeutic effects.

Analysis of the structure, substrate specificity, and mechanism of squash glycerol-3-phosphate (1)-acyltransferase.

BACKGROUND: Glycerol-3-phosphate (1)-acyltransferase(G3PAT) catalyzes the incorporation of an acyl group from either acyl-acyl carrier proteins (acylACPs) or acyl-CoAs into the sn-1 position of glycerol 3-phosphate to yield 1-acylglycerol-3-phosphate. G3PATs can either be selective, preferentially using the unsaturated fatty acid, oleate (C18:1), as the acyl donor, or nonselective, using either oleate or the saturated fatty acid, palmitate (C16:0), at comparable rates. The differential substrate specificity for saturated versus unsaturated fatty acids seen within this enzyme family has been implicated in the sensitivity of plants to chilling temperatures. RESULTS: The three-dimensional structure of recombinant G3PAT from squash chloroplast has been determined to 1.9 A resolution by X-ray crystallography using the technique of multiple isomorphous replacement and provides the first representative structure of an enzyme of this class. CONCLUSIONS: The tertiary structure of G3PAT comprises two domains, the larger of which, domain II, features an extensive cleft lined by hydrophobic residues and contains at one end a cluster of positively charged residues flanked by a H(X)(4)D motif, which is conserved amongst many glycerolipid acyltransferases. We predict that these hydrophobic and positively charged residues represent the binding sites for the fatty acyl substrate and the phosphate moiety of the glycerol 3-phosphate, respectively, and that the H(X)(4)D motif is a critical component of the enzyme's catalytic machinery.

Mutations of adenomatous polyposis coli and beta-catenin genes during progression of lung tumors induced by N-nitrosobis(2-hydroxypropyl)amine in rats.

In the present study, we investigated mutations of the adenomatous polyposis coli (APC) and beta-catenin genes to clarify possible molecular mechanisms underlying development of lung tumors induced by N-nitrosobis(2-hydroxypropyl)amine (BHP) in rats. Male Wistar rats, 6 weeks of age, were given 2000 ppm BHP in drinking water for 12 weeks and then maintained without further treatment until sacrifice at week 25 DNA was extracted from paraffin-embedded tissues, and PCR-single-strand conformation polymorphism analysis, followed by nucleotide sequencing, was performed. No APC mutations were detected in 17 hyperplasias, but 2 of 15 adenomas (13.3%) and 8 of 20 adenocarcinomas (40.0%) showed changes within exon 1 to the mutation cluster region in exon 15. For beta-catenin, no mutations were detected in 17 hyperplasias, but 3 of 15 adenomas (20.0%) and 5 of 20 adenocarcinomas (25.0%) had alterations within or flanking codons corresponding to important phosphorylation sites. Immunohistochemical staining showed beta-catenin protein localized in the cell membranes in the surrounding normal-appearing lung and 216 hyperplasias and localized mainly in the cytoplasm and/or nucleus in 10 of 37 adenomas (27.0%) and 21 of 40 adenocarcinomas (52.5%). These results suggest that the APC-beta-catenin-T-cell factor signaling pathway is involved in the acquisition of growth advantage from adenomas to adenocarcinomas in BHP-induced rat lung carcinogenesis.

[Chondrosarcoma of rib origin; report of a case].

Chondrosarcoma of rib origin is rare. A 50-year-old man without symptom was pointed out an abnormal shadow on chest X-ray. Computed tomography (CT) showed a low density mass arising from the right chest wall, and a CT-guided needle aspiration biopsy disclosed the tumor consisted of cartilage matrix with a partial necrosis. We suspected the tumor to be a chondrosarcoma of rib origin and performed a wide resection with the right 3rd and 4th ribs. The defect of the chest wall was repaired with double prolene mesh. Histological examination revealed grade 2 chondrosarcoma. Postoperative course has been uneventful for 25 months.

Clinical evaluation of microcystic macular edema in patients with glaucoma.

PurposeTo investigate the prevalence of microcystic macular edema (MME) in patients with glaucoma and the relationship between glaucomatous visual field defects and MME.Patients and methodsWe analyzed 636 eyes of 341 glaucoma patients who underwent spectral domain optical coherence tomography (SD-OCT). MME was defined as vacuoles observed in the inner nuclear layer (INL) on SD-OCT. Quantitative assessment of MME area was performed using en-face imaging obtained swept-source OCT (SS-OCT) and Adobe Photoshop CS6 Extended software. These values were compared with the visual field results with the Humphrey field analyzer.ResultsMME was observed in 1.6% of eyes. The visual field mean deviation (MD), pattern standard deviation (PSD) and visual acuity was significantly worse (P= 0.023, P=0.037, and P=0.018, respectively) in eyes with MME. The average MME area was 2.38±1.43%. There was no significant correlation between visual field deficits and MME area.ConclusionsThe MME detection rate based on general inspection was 1.6%. MME in glaucomatous eyes were associated with worse MD, PSD, and visual acuity. Further research is needed to increase the number of cases to allow for more detailed analysis.

Characteristics of meso-particles formed in coagulation process causing irreversible membrane fouling in the coagulation-microfiltration water treatment.

In coagulation-membrane filtration water treatment processes, it is still difficult to determine the optimal coagulation condition to minimize irreversible membrane fouling. In microfiltration (MF), meso-particles (i.e., 20 nm-0.5 µm) are thought to play an important role in irreversible membrane fouling, especially their characteristics of particle number (PN) and zeta potential (ZP). In this study, a new nanoparticle tracker combined a high-output violet laser with a microscope was developed to identify the physicochemical characteristics of these microscopic and widely dispersed meso-particles. The effects of pH and coagulant dose on ZP and PN of micro-particles (i.e., >0.5 µm) and meso-particles were investigated, and then coagulation-MF tests were conducted. As the result, irreversible membrane fouling was best controlled for both types of membranes, while meso-particle ZP approached zero at around pH 5.5 for both types of natural water. Since PN was greatest under these conditions, ZP is more important in determining the extent of irreversible membrane fouling than PN. However, the acidic condition to neutralize meso-particles is not suitable for actual operation, as considering residual aluminum concentration, pipe corrosion, and chlorination efficiency. It is therefore necessary to investigate coagulants or other methods for the appropriate modification of meso-particle characteristics.

Glycerol-3-phosphate acyltransferase in plants.

Glycerol-3-phosphate acyltransferase (GPAT) catalyzes the transfer of an acyl group from an acyl donor to the sn-1 position of glycerol 3-phosphate. The plant cell contains three types of GPAT, which are located in the chloroplasts, mitochondria and cytoplasm, respectively. The enzyme in chloroplasts is soluble and uses acyl-(acyl-carrier protein) as the acyl donor, whereas the enzymes in the mitochondria and the cytoplasm are bound to membranes and use acyl-CoA as the acyl donor. cDNAs for GPAT of chloroplasts have been cloned from several plants, and the gene for the enzyme has been cloned from Arabidopsis thaliana. The amino acid sequences deduced from the nucleotide sequences of cDNAs indicate that the product of translation is a precursor of about 460 amino acid residues, which consists of a leader sequence of about 70 amino acid residues and a mature protein of about 400 residues, with a molecular mass of about 42 kDa. Genetic engineering of the unsaturation of fatty acids has been achieved by manipulation of the cDNA for the GPAT found in chloroplasts and has allowed modification of the ability of tobacco to tolerate chilling temperatures.

Transition of lipid phase in aqueous dispersions of diacylglyceryltrimethylhomoserine.

The phase transition in the lipid phase of aqueous dispersions of diacylglyceryltrimethylhomoserine (DGTS) was measured by fluorescence depolarization of parinaric acid and differential scanning calorimetry. In both techniques, the phase transition temperatures (Tm) of 1-palmitoyl-2-stearoyl DGTS and of 1,2-distearoyl DGTS were 53 and 59 degrees C, respectively. Each of these Tm values was significantly higher than the Tm value of phosphatidylcholine with an identical combination of fatty acids. This suggests that the intermolecular interactions of DGTS molecules are slightly different from those of phosphatidylcholine molecules.

Temperature shift-induced responses in lipids in the blue-green alga, Anabaena variabilis: the central role of diacylmonogalactosylglycerol in thermo-adaptation.

Changes in fatty acids and lipid molecular species after shift of growth temperature were studied in the blue-green alga, Anabaena variabilis. In the first 10 h after a temperature shift from 38 to 22 degrees C, lipid synthesis was markedly suppressed. During this period most of the palmitic acid of the diacylmonogalactosylglycerol was desaturated to palmitoleic acid. Thereafter lipid synthesis resumed, and, in the following hours, the relative contents of palmitic and palmitoleic acids were almost restored to original levels. On the other hand, the oleic and linoleic acids were almost restored to original levels. On the other hand, the oleic and inoleic acids were desaturated to alpha-linolenic acid in all the lipid classes. The desaturation reaction of the C18 acids were slower than those of the C16 acids. In the first 5 h after a growth-temperature shift from 22 to 38 degrees C, lipid synthesis was considerably stimulated. During this period, the relative content of palmitic acid increased and that of palmitoleic acid decreased in the diacylmonogalactosylglycerol, and in the following 20 h, they were restored. The oleic and linoleic acids increased with a concomitant decrease in alpha-linolenic acid in all the lipid classes. The decreases in unsaturation in the C16 and C18 acids were due to the stimulated synthesis of more saturated fatty acids. Among the major molecular species of the lipids a particular change was seen in 1-oleoyl-2-palmitoylmonogalactosyl-sn-glycerol. This species rapidly decreased after the downward temperature shift and rapidly increased after the upward temperature shift. From the viewpoint of thermo-adaptive regulation of membrane fluidity, the central role played by the diacylmonogalactosylglycerol in temperature acclimation is discussed.

Purification and characterization of 33 kilodalton protein of spinach chloroplasts.

A protein was prepared from spinach chloroplasts in a highly purified form. The isoelectric point of the protein was 5.2. The apparent molecular weight was estimated to be 33 000 by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate and urea, and 34 000 by gel filtration column chromatography with Sephadex G-100. The protein was provisionally named '33 kilodalton protein' according to the molecular weight. The absorption spectrum of the protein did not show any absorption band in the visible region. No histidine was found in the amino acid analysis of the protein. The 33 kilodalton protein was released from the thylakoid membrane by EDTA-treatment and also by sonic oscillation. The protein was bound to System II particles, but not to System I particles.

Chemical modification by trinitrobenzenesulfonate of a lipid and proteins of intracytoplasmic membranes isolated from Chromatium vinosum and Azotobacter vinelandii.

1. The structure of intracytoplasmic membranes of a photosynthetic bacterium chromatium vinosum and a nitrogen-fixing bacterium Azotobacter vinelandii was studied by chemical modification of amino groups of phosphatidylethanolamine and proteins with trinitrobenzenesulfonate. 2. Almost all the constituents of intracytoplasmic membranes of C. vinosum were solubilized in a mixture of chloroform, methanol and trichloroacetic acid. One-third of proteins in the intracytoplasmic membranes of C. vinosum was found solubilized in a mixture of chloroform and methanol. By using a column chromatography with Sephadex LH-20 in organic solvents, the unmodified as well as the trinitrophenylated proteins and also the trinitrophenylated phosphatidylethanolamine were separated from the other colored substances. 3. In the chemical modification of the intracytoplasmic membrane preparations, 30% of phosphatidylethanolamine and 15% of protein amino groups in C. vinosum and 45% of phosphatidylethanolamine and 20% of protein amino groups in A. vinelandii were estimated to be exposed to the aqueous phase. In the single-layered liposomes composed of phosphatidylethanolamine and phosphatidylglycerol with a ratio of 2:1, 40% of phosphatidylethanolamine were estimated to be exposed to the aqueous phase.

Photosynthetic electron transport and phosphorylation reactions in thylakoid membranes from the blue-green alga Anacystis nidulans.

Thylakoid membranes were prepared from the blue-green alga, Anacystis nidulans with lysozyme treatment and a short period of sonic oscillation. The thylakoid membrane preparation was highly active in the electron transport reactions such as the Hill reactions with ferricyanide and with 2,6-dichlorophenolindophenol, the Mehler reaction mediated by methyl viologen and the system 1 reaction with methyl viologen as an electron acceptor and 2,6-dichlorophenolindophenol and ascorbate as an electron donor system. The Hill reaction with ferricyanide and the system 1 reaction was stimulated by the phosphorylating conditions. The cyclic and non-cyclic phosphorylation was also active. These findings suggest that the preparation of thylakoid membranes retained the electron transport system from H2O to reaction center 1, and that the phosphorylation reaction was coupled to the Hill reaction and the system 1 reaction.

Analyses of absorption and fluorescence spectra of water-soluble chlorophyll proteins, pigment system II particles and chlorophyll a in diethylether solution by the curve-fitting method.

Absorption and fluorescence spectra in the red region of water-soluble chlorophyll proteins, Lepidium CP661, CP663 and Brassica CP673, pigment System II particles of spinach chloroplasts and chlorophyll a in diethylether solution at 25 degrees C were analyzed by the curve-fitting method (French, C.S., Brown, J.S. and Lawrence, M.C. (1972) Plant Physiol 49, 421--429). It was found that each of the chlorophyll forms of the chlorophyll proteins and the pigment System II particles had a corresponding fluorescence band with the Stokes shift ranging from 0.6 to 4.0 nm. The absorption spectrum of chlorophyll a in diethylether solution was analyzed to one major band with a peak at 660.5 nm and some minor bands, while the fluorescence spectrum was analyzed to one major band with a peak at 664.9 nm and some minor bands. A mirror image was clearly demonstrated between the resolved spectra of absorption and fluorescence. The absorption spectrum of Lepidium CP661 was composed of a chlorophyll b form with a peak at 652.8 nm and two chlorophyll a forms with peaks at 662.6 and 671.9 nm. The fluorescence spectrum was analyzed to five component bands. Three of them with peaks at 654.8, 664.6 and 674.6 nm were attributed to emissions of the three chlorophyll forms with the Stokes shift of 2.0--2.7 nm. The absorption spectrum of Brassica CP673 had a chlorophyll b form with a peak at 653.7 nm and four chlorophyll a forms with peaks at 662.7, 671.3, 676.9 and 684.2 nm. The fluorescence spectrum was resolved into seven component bands. Four of them with peaks at 666.7, 673.1, 677.5 and 686.2 nm corresponded to the four chlorophyll a forms with the Stokes shift of 0.6--4.0 nm. The absorption spectrum of the pigment System II particles had a chlorophyll b form with a peak at 652.4 nm and three chlorophyll a forms with peaks at 662.9, 672.1 and 681.6 nm. The fluorescence spectrum was analyzed to four major component bands with peaks at 674.1, 682.8, 692.0 and 706.7 nm and some minor bands. The former two bands corresponded to the chlorophyll a forms with peaks at 672.1 and 681.6 nm with the Stokes shift of 2.0 and 1.2 nm, respectively. Absorption spectra at 25 degrees C and at --196 degrees C of the water-soluble chlorophyll proteins were compared by the curve-fitting methods. The component bands at --196 degrees C were blue-shifted by 0.8--4.1 nm and narrower in half widths as compared to those at 25 degrees C.

Structure and expression of fatty acid desaturases.

Fatty acid desaturases are enzymes that introduce double bonds into fatty acyl chains. They are present in all groups of organisms, i.e., bacteria, fungi, plants and animals, and play a key role in the maintenance of the proper structure and functioning of biological membranes. The desaturases are characterized by the presence of three conserved histidine tracks which are presumed to compose the Fe-binding active centers of the enzymes. Recent findings on the structure and expression of different types of fatty acid desaturase in cyanobacteria, plants and animals are reviewed in this article. Roles of individual desaturases in temperature acclimation and principles of regulation of the desaturase genes are discussed.