Protective Effect of Some Essential Oils Against Gamma-Radiation Damages in Tetrahymena pyriformis Exposed to Cobalt-60 Source.

The main purpose of this study was to investigate the protective effect of Rosmarinus officinalis, Origanum compactum, Lavandula angustifolia, and Eucalyptus globulus essential oils (EOs) against gamma-radiation-induced damages on Tetrahymena pyriformis growing in presence of cobalt-60 source. The chemical composition of the 4 EOs was analyzed by gas chromatography-mass spectrometry. The protective effects of EOs on growth, on morphology, and on some metabolic enzymes and antioxidant markers have been evaluated. Thus, addition of EOs significantly improves the growth parameters (generation number and time) in irradiating conditions. All EOs allowed restoring growth parameters over more than 90% compared to the controls. The morphological analysis indicated that T. pyriformis cells growing in irradiating conditions were able to regain their normal form in presence of the different EOs. Our results indicate that the 4 EOs also have protective effects on some metabolic enzymes. They allowed recovering totally or partially the glyceraldehyde 3-phosphate dehydrogenase and the succinate dehydrogenase activities compared to the controls. Moreover, the addition of EOs reduced the lipid peroxidation level and decreased the activities of catalase and superoxide dismutase induced by the gamma-radiation exposure. A more pronounced protective effect was found for O. compactum and L. angustifolia EOs compared to R. officinalis and E. globulus EOs. These results suggest that the studied EOs are efficient natural antioxidants that could offer protection against gamma-radiation-induced damages and can therefore be useful in clinical medicine.

Comparative study of the antioxidant activity of the essential oils of five plants against the H2O2 induced stress in Saccharomyces cerevisiae.

The purpose of this work was to investigate the protective effect of five essential oils (EOs); Rosmarinus officinalis, Thymus vulgaris, Origanum compactum Benth., Eucalyptus globulus Labill. and Ocimum basilicum L.; against oxidative stress induced by hydrogen peroxide in Saccharomyces cerevisiae. The chemical composition of the EOs was analyzed by gas chromatography (GC) and gas chromatography-mass spectrometry (GC/MS). The in vitro antioxidant activity was evaluated and the protective effect of EOs was investigated. Yeast cells were pretreated with different concentrations of EOs (6.25-25 µg/ml) for an hour then incubated with H2O2 (2 mM) for an additional hour. Cell viability, antioxidants (Catalase, Superoxide dismutase and Glutathione reductase) and metabolic (Succinate dehydrogenase) enzymes, as well as the level of lipid peroxidation (LPO) and protein carbonyl content (PCO) were evaluated. The chemical composition of EOs has shown the difference qualitatively and quantitatively. Indeed, O. compactum mainly contained Carvacrol, O. basilicum was mainly composed of Linalool, T. vulgaris was rich in thymol, R. officinalis had high α-Pinene amount and for E. globulus, eucalyptol was the major compound. The EOs of basil, oregano and thyme were found to possess the highest amount of total phenolic compounds. Moreover, they have shown the best protective effect on yeast cells against oxidative stress induced by H2O2. In addition, in a dose dependent manner of EOs in yeast medium, treated cells had lower levels of LPO, lower antioxidant and metabolic enzymes activity than cells exposed to H2O2 only. The cell viability was also improved. It seems that the studied EOs are efficient natural antioxidants, which can be exploited to protect against damages and serious diseases related to oxidative stress.

Changes in Growth, Morphology, and Physiology of Tetrahymena pyriformis Exposed to Continuous Cesium-137 and Cobalt-60 Gamma-Radiation.

This study investigated the effects of gamma-radiation on Tetrahymena pyriformis. The experimental approach consists of exposing T. pyriformis growing in presence of Cesium-137 (137Cs) at dose rates of 1, 2, 4, and 6 cGy h-1 and Cobalt-60 (60Co) at dose rates of 8, 10, 15, and 20 cGy h-1. The radiation doses effects on growth, morphology, some metabolic enzymes, and reactive oxygen species (ROS) markers have been evaluated. When cells were growing in irradiating conditions at dose rates beyond 4 cGy h-1, a decreasing of cells and generation numbers with a prolongation of generation time and a change of morphological aspect with rounding-off of cells were observed compared to the control. The 50%-inhibitory dose (ID50) for radiation was estimated at 1568.72 ± 158.45 cGy. The gamma-radiation at dose rates more than 6 cGy h-1, affected both glyceraldehyde 3-phosphate dehydrogenase and succinate dehydrogenase by inhibiting their activities. All of these effects were more pronounced when cells were irradiated at the dose rate of 20 cGy h-1 using 60Co source. For ROS markers generated by gamma-radiation in T. pyriformis, the results showed an increase of the lipid peroxidation in cells grown in presence of gamma-radiation at dose rates more than 6 cGy h-1 and an enhancement in catalase and superoxide dismutase activities from the dose rate of 1 cGy h-1. These encouraging results suggested the use of T. pyriformis as a unicellular model cell to investigate other aspects of the response to ionizing radiation.

IL-1 and CD40/CD40L platelet complex: elements of induction of Crohn's disease and new therapeutic targets.

Ulcerative colitis (UC) and Crohn's disease (CD) are chronic and multifactorial diseases that affect the intestinal tract, both characterized by recurrent inflammation of the intestinal mucosa, resulting in abdominal pain, diarrhea, vomiting and, rectal bleeding. Inflammatory bowel diseases (IBD) regroup these two disorders. The exact pathological mechanism of IBD remains ambiguous and poorly known. In genetically predisposed patients, defects in intestinal mucosal barrier are due to an uncontrolled inflammatory response to normal flora. In addition to the genetic predisposition, these defects could be triggered by environmental factors or by a specific lifestyle which is widely accepted as etiological hypothesis. The involvement of the CD40/CD40L platelet complex in the development of IBD has been overwhelmingly demonstrated. CD40L is climacteric in cell signalling in innate and adaptive immunity, the CD40L expression on the platelet cell surface gives them an immunological competence. The IL-1, a major inflammation mediator could be involved in different ways in the development of IBD. Here, we provide a comprehensive review regarding the role of platelet CD40/CD40L in the pathophysiological effect of IL-1 in the development of Crohn's disease (CD). This review could potentially help future approaches aiming to target these two pathways for therapeutic purposes and elucidate the immunological mechanisms driving gut inflammation.

Effect of Peroxisome Proliferator-Activated Receptor-γ Coactivator-1 Alpha Variants on Spontaneous Clearance and Fibrosis Progression during Hepatitis C Virus Infection in Moroccan Patients.

Hepatitis C virus (HCV) is still one of the main causes of liver disease worldwide. Metabolic disorders, including non-alcoholic fatty liver disease (NAFLD), induced by HCV have been shown to accelerate the progression of fibrosis to cirrhosis and to increase the risk of hepatocellular carcinoma. An optimal peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PPARGC1A) activity is crucial to prevent NAFLD installation. The present study aims to investigate the associations between two common PPARGC1A polymorphisms (rs8192678 and rs12640088) and the outcomes of HCV infection in a North African context. A series of 592 consecutive Moroccan subjects, including 292 patients with chronic hepatitis C (CHC), 100 resolvers and 200 healthy controls were genotyped using a TaqMan allelic discrimination assay. PPARGC1A variations at rs8192678 and rs12640088 were not associated with spontaneous clearance of HCV infection (adjusted ORs = 0.76 and 0.79 respectively, P > 0.05, for both). Furthermore, multivariable logistic regression analysis showed that both SNPs were not associated with fibrosis progression (OR = 0.71; 95% CI 0.20-2.49; P = 0.739; OR = 1.28; 95% CI 0.25-6.54; P = 0.512, respectively). We conclude that, in the genetic context of South Mediterranean patients, rs8192678 and rs12640088 polymorphisms of PPARGC1A are neither associated with spontaneous clearance nor with disease progression in individuals infected with HCV.

Novel Mutation in AIFM1 Gene Associated with X-Linked Deafness in a Moroccan Family.

INTRODUCTION: Auditory neuropathy is a hearing disorder where outer hair cell function within the cochlea is normal, but inner hair cell and/or the auditory nerve function is disrupted. It is a heterogeneous disorder, which can have either congenital or acquired causes. METHODS: We found a disease-segregating mutation in the X-linked AIFM1 gene through whole-exome sequencing, encoding the apoptosis-inducing factor mitochondrion-associated 1. RESULTS: The impact of the c.1045A>G; p.(Ser349Gly) mutation on the AIFM1 protein was predicted using different bioinformatics tools. The pedigree analysis in the examined family was consistent with X-linked dominant inheritance. DISCUSSION/CONCLUSION: To our knowledge, this is the first study that identifies a mutation in the AIFM1 gene in Moroccan patients suffering from X-linked auditory neuropathy.

Two novel homozygous missense mutations identified in the BSND gene in Moroccan patients with Bartter's syndrome.

OBJECTIVES: Hearing loss (HL) is one of the most common sensorineural disorders. In the present study, we identified two novel missense mutations in BSND gene causing Bartter syndrome type IV which is a genetic disease with an autosomal recessive transmission, characterized by hypokalaemia, metabolic alkalosis, an elevation in plasma renin activity and hyperaldosteronism as well as sensorineural deafness. METHODS: Whole-exome sequencing was performed to study the genetic causes of Hearing loss in two unrelated patients from two Moroccan families. RESULTS: The two novel homozygous mutations p.Arg8Gly (c.22C > G), p.Thr36Asn (c.107C > A) in exon 1 of BSND gene which encodes barttin were identified in 7 patients belonging to two unrelated families originated from central region of Morocco. CONCLUSION: We identified two novel missense mutations p.Arg8Gly and p.Thr36Asn in exon 1 of BSND gene; both mutations were described for the first time in Moroccan patients with Bartter syndrome type IV.

Effect of MBOAT7 variant on hepatitis B and C infections in Moroccan patients.

The outcomes of HBV and HCV infections are associated both with viral and host genetic factors. Here, we explore the role of a genetic variation located in membrane-bound O-acyltransferase domain-containing protein 7 (MBOAT7) gene on spontaneous clearance of HBV and HCV infections and on liver fibrosis. We genotyped MBOAT7 rs641738 polymorphism in 971 consecutive Moroccan subjects, including 288 patients with chronic hepatitis C (CHC), 98 cases with spontaneous clearance of HCV, 268 patients with chronic hepatitis B (CHB), 126 spontaneously cleared HBV infections and 191 healthy controls. MBOAT7 rs641738 variant is not associated with spontaneous clearance of HBV (OR = 0.67, 95% CI: 0.39-1.14; p = 0.131) and HCV infections (OR = 1.33, 95% CI: 0.79-2.23; p = 0.278). Furthermore, multivariable logistic regression analysis adjusted for biologically relevant covariates and potential confounders associated with the risk of liver disease progression revealed that MBOAT7 rs641738 is not associated either with fibrosis progression in CHC group (OR = 1.12; 95% CI: 0.55-2.28; p = 0.761) or with chronic progressive state in CHB patients (OR = 0.81; 95% CI: 0.41-1.61; p = 0.547). We conclude that the variant MBOAT7 rs641738 genotype is not associated with spontaneous clearance of HBV and HCV infections or with the progression of liver disease in chronic hepatitis B or C in a genetic context of Mediterranean patients.

First Molecular Identification and Phylogeny of Moroccan Anopheles sergentii (Diptera: Culicidae) Based on Second Internal Transcribed Spencer (ITS2) and Cytochrome c Oxidase I (COI) Sequences.

Anopheles sergentii known as the "oasis vector" or the "desert malaria vector" is considered the main vector of malaria in the southern parts of Morocco. Its presence in Morocco is confirmed for the first time through sequencing of mitochondrial DNA (mDNA) cytochrome c oxidase subunit I (COI) barcodes and nuclear ribosomal DNA (rDNA) second internal transcribed spacer (ITS2) sequences and direct comparison with specimens of A. sergentii of other countries. The DNA barcodes (n = 39) obtained from A. sergentii collected in 2015 and 2016 showed more diversity with 10 haplotypes, compared with 3 haplotypes obtained from ITS2 sequences (n = 59). Moreover, the comparison using the ITS2 sequences showed closer evolutionary relationship between the Moroccan and Egyptian strains than the Iranian strain. Nevertheless, genetic differences due to geographical segregation were also observed. This study provides the first report on the sequence of rDNA-ITS2 and mtDNA COI, which could be used to better understand the biodiversity of A. sergentii.

Assessment of metals bioaccumulation and bioavailability in mussels Mytilus galloprovincialis exposed to outfalls pollution in coastal areas of Casablanca.

The present work aims to study the metallic contamination of four sampling sites located nearby major sewage outfalls of the Casablanca coast (Morocco), using indigenous mussels Mytilus galloprovincialis as bioindicators of pollution. This research offered the opportunity to study trace metals bioaccumulation mechanisms, which represent a major factor in assessment processes of the pollution effects in coastal ecosystem health. The bioavailability and the bioaccumulation of trace metals (Cu, Zn, Ni, Pb) were evaluated in order to compare the metallic contamination in mussels' tissues and find a possible correlation with physiological parameters of this filter feeding species. Our results showed a significant spatiotemporal variation of bioaccumulation, compared to control. A significant correlation coefficient between metals (Zn and Pb) bioavailability and physiological index (CI) was revealed in mussels from the most polluted location. The seasonal variation of trace metal accumulation was also raised; the highest values recorded during the dry period.

A novel mutation in SLITRK6 causes deafness and myopia in a Moroccan family.

Deafness and myopia syndrome is characterized by moderate-profound, bilateral, congenital or prelingual deafness and high myopia. Autosomal recessive non-syndromic hearing loss is one of the most prevalent human genetic sensorineural defects. Myopia is by far the most common human eye disorder that is known to have a clear heritable component. The analysis of the two exons of SLITRK6 gene in a Moroccan family allowed us to identify a novel single deleterious mutation c.696delG, p.Trp232Cysfs*10 at homozygous state in the exon 2 of the SLITRK6, a gene reported to cause deafness and myopia in various populations.

Homozygous mutations in PJVK and MYO15A genes associated with non-syndromic hearing loss in Moroccan families.

OBJECTIVES: Autosomal recessive non-syndromic hearing loss is a heterogeneous disorder and the most prevalent human genetic sensorineural defect. In this study, we investigated the geneticcause of sensorineural hearing loss in Moroccan patients and presented the importance of whole exome sequencing (WES) to identify candidate genes in two Moroccan families with profound deafness. METHODS: After excluding mutations previously reported in Moroccan deaf patients, whole exome sequencing was performed and Sanger sequencing was used to validate mutations in these genes. RESULTS: Our results disclosed the c.113_114insT (p.Lys41GlufsX8) and c.406C > T (p.Arg130X) homozygous mutations in PJVK and a homozygous c.5203C > T (p.Arg1735Trp) mutation in MYO15A, both genes responsible for non-syndromic recessive hearing loss DFNB59 and DFNB3, respectively. CONCLUSION: We identified in Moroccan deaf patients two mutations in PJVK and one mutation in MYO15A described for the first time in association with non-syndromic recessive hearing loss. These results emphasize that whole exome sequencing is a powerful diagnostic strategy to identify pathogenic mutations in heterogeneous disorders with many various causative genes.

Update of the spectrum of GJB2 gene mutations in 152 Moroccan families with autosomal recessive nonsyndromic hearing loss.

Deafness is one of the most common genetic diseases in humans and is subject to important genetic heterogeneity. The most common cause of non syndromic hearing loss (NSHL) is mutations in the GJB2 gene. This study aims to update and evaluate the spectrum of GJB2 allele variants in 152 Moroccan multiplex families with non syndromic hearing loss. Seven different mutations were detected: c.35delG, p.V37I, p.E47X, p.G200R, p.Del120E, p.R75Q, the last three mutations were described for the first time in Moroccan deaf patients, in addition to a novel nonsense mutation, the c.385G>T which is not referenced in any database. Sixty six families (43.42%) have mutations in the coding region of GJB2, while the homozygous c.35delG mutation still to date the most represented 51/152 (33.55%). The analysis of the geographical distribution of mutations located in GJB2 gene showed more allelic heterogeneity in the north and center compared to the south of Morocco. Our results showed that the GJB2 gene is a major contributor to non syndromic hearing loss in Morocco. Thus, this report of the GJB2 mutations spectrum all over Morocco has an important implication for establishing a suitable molecular diagnosis.

Correlation between the plasma fibrinogen concentration and coronary heart disease severity in Moroccan patients with type 2 diabetes. Prospective study.

AIM: The present study aims at determining the relationship between the plasma fibrinogen concentration and the severity of coronary heart disease in type 2 diabetic patients. METHODS: Prospective analytical survey, based on a sample of 120 subjects divided in four groups: 30 non diabetic coronary patients (G1), 30 coronary diabetic patients (G2), 30 non-coronary diabetic patients (G3), and 30 healthy subjects (G4). RESULTS: The average age was 59.58±7.88 years; female gender predominated by 52.5%. The plasma fibrinogen concentration corresponded to 3.46g/L±0.86 in G1; 3.73g/L±1.11 in G2; 3.06g/L±0.98 in G3 and 2.46g/L±0.51 in G4; with a significant difference between the four groups (P=0.001). The plasma fibrinogen concentration increased in parallel with the cardiovascular risk (P=0.0001); there was also a significant correlation between the plasma fibrinogen concentration and the clinical and para-clinical coronary disease severity (respectively P=0.005 and P=0.0001). A positive correlation between the plasma fibrinogen concentration and hyperglycemia (P=0.035) was found in G4. But no correlation with the lipids parameters, except for the low density-lipoproteins in G3 (P=0.035). CONCLUSION: In the Moroccan population, the plasma fibrinogen concentration was positively and significantly correlated with the coronary heart disease severity.

Differential regulation of peroxisome proliferator-activated receptor (PPAR)-alpha1 and truncated PPARalpha2 as an adaptive response to fasting in the control of hepatic peroxisomal fatty acid beta-oxidation in the hibernating mammal.

Seasonal obesity and fasting-associated hibernation are the two major metabolic events governing hepatic lipid metabolism in hibernating mammals. In this process, however, the role of the nuclear receptor known as peroxisome proliferator-activated receptor (PPAR)-alpha has not been elucidated yet. Here we show, as in human, that jerboa (Jaculus orientalis) liver expresses both active wild-type PPARalpha (PPARalpha1wt) and truncated PPARalpha forms and that the PPARalpha1wt to truncated PPARalpha2 ratio, which indicates the availability of active PPARalpha1wt, is differentially regulated during fasting-associated hibernation. Functional activation of hepatic jerboa PPARalpha, during prehibernating and hibernating states, was demonstrated by the induction of its target genes, which encode peroxisomal proteins such as acyl-CoA oxidase 1, peroxisomal membrane protein 70, and catalase, accompanied by a concomitant induction of PPARalpha thermogenic coactivator PPARgamma coactivator-1alpha. Interestingly, sustained activation of PPARalpha by its hypolipidemic ligand, ciprofibrate, abrogates the adaptive fasting response of PPARalpha during prehibernation and overinduces its target genes, disrupting the prehibernation fattening process. In striking contrast, during fasting-associated hibernation, jerboas exhibit preferential up-regulation of hepatic peroxisomal fatty acid oxidation instead of the mitochondrial pathway, which is down-regulated. Taken together, our results strongly suggest that PPARalpha is subject to a hibernation-dependent splicing regulation in response to feeding-fasting conditions, which defines the activity of PPARalpha and the activation of its target genes during hibernation bouts of jerboas.

Sensitivity of liver metabolism in jerboa (Jaculus orientalis) to ciprofibrate, a peroxisome proliferator.

Ciprofibrate is a well-known drug used to normalize lipid parameters and fibrinogen in atherosclerosis patients. In laboratory rodents such as rats or mice, ciprofibrate exhibits peroxisome proliferator activity. However, to date, no clear alterations or side effects caused by ciprofibrate have been noted in humans. In order to further investigate such possible relationships, we studied the effects of sustained ciprofibrate treatment in jerboas (Jaculus orientalis). In these rodents, ciprofibrate does not induce hepatomegaly or promote liver cell DNA replication, confirming that this species more closely resembles humans than do rats or mice. The jerboas were treated daily with ciprofibrate at 3 mg/kg body weight for 4 weeks. Subcellular markers, clinical enzymes and enzymatic antioxidant defenses were then assessed. The results showed a strong decrease in peroxisomal catalase activity and an increase in the level of malondialdehyde (a stress biomarker). Moreover, ciprofibrate in vivo and in vitro inhibited D-3-hydroxybutyrate dehydrogenase, a mitochondrial enzyme of the ketone body interconversion that is important in redox balance (NAD+/NADH+H+ ratio). In conclusion, under these conditions, ciprofibrate induced alterations in the liver oxidative metabolism.

Prehibernation and hibernation effects on the D-3-hydroxybutyrate dehydrogenase of the heavy and light mitochondria from liver jerboa (Jaculus orientalis) and related metabolism.

The D-3-hydroxybutyrate dehydrogenase (BDH) (EC 1.1.1.30) from liver jerboa (Jaculus orientalis), a ketone body converting enzyme in mitochondria, in two populations of mitochondria (heavy and light) has been studied in different jerboa states (euthermic, prehibernating and hibernating). The results reveal: (1) important variations between states in terms of ketones bodies, glucose and lipid levels; (2) significant differences between the BDH of the two mitochondrial populations in term of protein expression and kinetic properties. These results suggest that BDH leads an important conformational change depending on the physiological state of jerboa. This BDH structural change could be the consequence of the lipid composition modifications in inner mitochondrial membrane leading to changes in BDH catalytic properties.

Characterization of two D-beta-hydroxybutyrate dehydrogenase populations in heavy and light mitochondria from jerboa (Jaculus orientalis) liver.

Mitochondrial membrane-bound and phospholipid-dependent D-beta-hydroxybutyrate dehydrogenase (BDH) (EC 1.1.1.30), a ketone body converting enzyme in mitochondria, has been studied in two populations of mitochondria (heavy and light) of jerboa (Jaculus orientalis) liver. The results reveal significant differences between the BDH of the two mitochondrial populations in terms of protein expression, kinetic parameters and physico-chemical properties. These results suggest that the beta-hydroxybutyrate dehydrogenases from heavy and light mitochondria are isoform variants. These differences in BDH distribution could be the consequence of cell changes in the lipid composition of the inner mitochondrial membrane of heavy and light mitochondria. These changes could modify both BDH insertion and BDH lipid-dependent catalytic properties.

Peroxisome proliferator-activated receptors as regulators of lipid metabolism; tissue differential expression in adipose tissues during cold acclimatization and hibernation of jerboa (Jaculus orientalis).

Brown (BAT) and white (WAT) adipose tissues play a key role in the body energy balance orchestrated by the central nervous system. Hibernators have developed a seasonal obesity to respond to inhospitable environment. Jerboa is one of the deep hibernator originated from sub-desert highlands. Thus, this animal represents an excellent model to study cold adaptation mechanism. We report that the adipogenic factor PPARgamma exhibits a differential expression between BAT and WAT at mRNA level. A specific induction was only seen in WAT of pre-hibernating jerboa. Interestingly, PPAR beta/delta is specifically induced in BAT and brain of pre-hibernating jerboa, highlighting for the first time the possible key role of this ubiquitous isoform in the cold adaptation of this true hibernator. Inductions of PPARgamma(2) in WAT and PPAR beta/delta in BAT are blunted by a hypolipemic drug, the ciprofibrate. These changes may be correlated with hibernation arrest and death of treated jerboa. Mitochondrial acyl-CoA dehydrogenase and peroxisomal acyl-CoA oxidase activities in brown and white adipose tissues are decreased up to 85% during cold acclimatization (without food privation). These enzyme activities are subject to a strong induction in BAT and in WAT (3.4-7.5 fold) during the hibernation period. The BAT thermogenesis marker is also largely induced (approximately 4 fold of UCP1 mRNA level) during pre-hibernation period. Unexpectedly, treatment with ciprofibrate deeply affects lipolysis in BAT by increasing acyl-CoA dehydrogenase activity (3.4 fold) and acyl-CoA oxidase at both activity and mRNA levels (2.8 and 3.8 fold, respectively) and enhances strongly UCP1 mRNA level (9.5 fold) during pre-hibernation.

Hibernation impact on the catalytic activities of the mitochondrial D-3-hydroxybutyrate dehydrogenase in liver and brain tissues of jerboa (Jaculus orientalis).

BACKGROUND: Jerboa (Jaculus orientalis) is a deep hibernating rodent native to subdesert highlands. During hibernation, a high level of ketone bodies i.e. acetoacetate (AcAc) and D-3-hydroxybutyrate (BOH) are produced in liver, which are used in brain as energetic fuel. These compounds are bioconverted by mitochondrial D-3-hydroxybutyrate dehydrogenase (BDH) E.C. 1.1.1.30. Here we report, the function and the expression of BDH in terms of catalytic activities, kinetic parameters, levels of protein and mRNA in both tissues i.e brain and liver, in relation to the hibernating process. RESULTS: We found that: 1/ In euthemic jerboa the specific activity in liver is 2.4- and 6.4- fold higher than in brain, respectively for AcAc reduction and for BOH oxidation. The same differences were found in the hibernation state. 2/ In euthermic jerboa, the Michaelis constants, KM BOH and KM NAD+ are different in liver and in brain while KM AcAc, KM NADH and the dissociation constants, KD NAD+and KD NADH are similar. 3/ During prehibernating state, as compared to euthermic state, the liver BDH activity is reduced by half, while kinetic constants are strongly increased except KD NAD+. 4/ During hibernating state, BDH activity is significantly enhanced, moreover, kinetic constants (KM and KD) are strongly modified as compared to the euthermic state; i.e. KD NAD+ in liver and KM AcAc in brain decrease 5 and 3 times respectively, while KD NADH in brain strongly increases up to 5.6 fold. 5/ Both protein content and mRNA level of BDH remain unchanged during the cold adaptation process. CONCLUSIONS: These results cumulatively explained and are consistent with the existence of two BDH enzymatic forms in the liver and the brain. The apoenzyme would be subjected to differential conformational folding depending on the hibernation state. This regulation could be a result of either post-translational modifications and/or a modification of the mitochondrial membrane state, taking into account that BDH activity is phospholipid-dependent.