Lotfi Fki

Cold hardening and sucrose treatment improve cryopreservation of date palm meristems

Date palm (Phoenix dactylifera L.) cv. Khenizi caulogenic meristems were initiated from achlorophyllous leaves excised from in vitro shoot cultures and then proliferated on a specific culture medium supplemented with 70 g dm−3 sucrose. Regeneration rates obtained when using standard vitrification, droplet-vitrification, and encapsulation-vitrification protocols reached 26.7, 60.0, and 40.0 %, respectively. Only explants smaller than 3 mm in diameter were found to survive cryogenic treatments. Sucrose preculture, cold hardening and loading solution pretreatments showed significant effects on regeneration rates. Moreover, our results indicate that both sucrose preculture and cold acclimation of explants increased proline content. Cryopreservation of date palm tissue with high proliferation capacity can directly benefit large scale micropropagation projects.

Inhibition of key digestive enzymes related to hyperlipidemia and protection of liver-kidney functions by Cystoseira crinita sulphated polysaccharide in high-fat diet-fed rats

The objective of this current study was to investigate the possible hyperlipidemic and antioxidative effects of Cystoseira crinita sulfated polysaccharide (CCSP) in rats fed with a high-fat diet, exhibited an inhibitory activity on pancreatic lipase in vitro. In vivo administration of this extract to HFD-rats lowered body weight and potentially inhibited key enzymes of lipid metabolism and absorption as lipase activity in both plasma and small intestine, which led to a notable decrease of blood LDL- cholesterol (LDL-Ch) and triglycerides (TG) levels, and an increase in HDL-cholesterol (HDL-Ch) levels in HFD-rats. CCSP was also observed to protect the liver-kidney functions efficiently, by decreasing of aspartate transaminase (AST), alanine transaminase (ALT), lactate dehydrogenase (LDH) and Creatine phosphokinase (CPK) activities and creatinine, albumin, T-bilirubin, uric acid, and urea rates in plasma. The histological analysis of liver and kidney tissues further established the positive effect of CCSP.

Ectopic Expression of Aeluropus littoralis Plasma Membrane Protein Gene AlTMP1 Confers Abiotic Stress Tolerance in Transgenic Tobacco by Improving Water Status and Cation Homeostasis

We report here the isolation and functional analysis of AlTMP1 gene encoding a member of the PMP3 protein family. In Aeluropus littoralis, AlTMP1 is highly induced by abscisic acid (ABA), cold, salt, and osmotic stresses. Transgenic tobacco expressing AlTMP1 exhibited enhanced tolerance to salt, osmotic, H2O2, heat and freezing stresses at the seedling stage. Under greenhouse conditions, the transgenic plants showed a higher level of tolerance to drought than to salinity. Noteworthy, AlTMP1 plants yielded two- and five-fold more seeds than non-transgenic plants (NT) under salt and drought stresses, respectively. The leaves of AlTMP1 plants accumulated lower Na+ but higher K+ and Ca2+ than those of NT plants. Tolerance to osmotic and salt stresses was associated with higher membrane stability, low electrolyte leakage, and improved water status. Finally, accumulation of AlTMP1 in tobacco altered the regulation of some stress-related genes in either a positive (NHX1, CAT1, APX1, and DREB1A) or negative (HKT1 and KT1) manner that could be related to the observed tolerance. These results suggest that AlTMP1 confers stress tolerance in tobacco through maintenance of ion homeostasis, increased membrane integrity, and water status. The observed tolerance may be due to a direct or indirect effect of AlTMP1 on the expression of stress-related genes which could stimulate an adaptive potential not present in NT plants.

Anti-obesity effect and protection of liver-kidney functions by Codium fragile sulphated polysaccharide on high fat diet induced obese rats

The present study investigates the hypolipidemic effects of sulphated polysaccharide obtained from Codium fragile (CFSP) in induced obese rats (HFD). The results showed an increase in body weight of HFD rats by 21.56% as compared to control normal rats. Moreover, serum lipase activity underwent an increase which led to an increase in the levels of total cholesterol (T-Ch), triglycerides (TG) and low density lipoprotein cholesterol (LDL-Ch) in serum associeted with a decrease in the level of high density lipoprotein cholesterol (HDL-Ch) in untreated HFD rats. This diet has disrupted the antioxidant status by decreasing the activities of antioxidant enzymes (superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX)) and subsequently an increase in thiobarbituric acid reactive substances (TBARS) level in liver and kidney of obese rats. All these disturbances are significantly corrected by CFSP administration with no fatty deposits in the liver and a protective effect against renal histological alteration. This confirms the important role of this polysaccharide in the fight against oxidative stress and the prevention of hyperlipidemia.

Inhibitory activities of Cystoseira crinita sulfated polysaccharide on key enzymes related to diabetes and hypertension: in vitro and animal study

Abstract The present study investigated the effect of the Cystoseira crinita sulfated polysaccharide (CCSP) on key enzymes activities related to diabetes in vitro and in diabetic rats. We found that CCSP inhibited pancreatic α-amylase with IC50 = 39.16 μg/ml and angiotensin I-converting enzyme (ACE) activity with IC50 = 58.35 μg/ml in vitro. In diabetic rats, the administration of CCSP reduced the activity of α-amylase in serum, pancreas, and intestine by 23%, 44.38%, and 45%, respectively as compared to untreated diabetic rats. Moreover, the administration of CCSP to surviving diabetic rats protects pancreas β cells from death and damage, which leads to insulin levels. The decrease in α-amylase and the increase in insulin level lead to a decrease in glucose rate by 56% as compared to untreated diabetic rats. The inhibitory action of α-amylase activity and hypoglycemic effect of CCSP were confirmed by oral glucose tolerance test (OGTT). In addition, the administration of CCSP to surviving diabetic rats normalizes lipid profile, stimulates antioxidant capacity, and prevents liver–kidney toxicities, evidenced by decrease in serum indices of liver and kidney toxicity and confirmed by histological analysis. The overall findings presented in this study demonstrate that the administration of CCSP to diabetic rats can make it a potentially strong candidate for industrial application as a pharmacological agent for the treatment of hyperglycemia, hyperlipidemia, and liver–kidney dysfunctions.

Hypolipidemic effect of dihydroisoquinoline oxaziridine in high-fat diet-fed rats

Obesity is a serious health problem that increases the risk of many complications, including diabetes and cardiovascular disease. This study aims to evaluate, for the first time, the effects of oxaziridine 3 on lipoprotein lipase activity in the serum of rats fed with a high-fat diet (HFD) on body weight, lipid profile and liver-kidney functions. The administration of oxaziridine 3 to HFD-rats lowered body weight and inhibited the lipase activity of obese rats leading to notable decrease of T-Ch, TGs and LDL-Ch levels accompanied with an increase in HDL-Ch concentration in serum. Moreover, the findings of this study revealed that oxaziridine 3 helped to protect liver tissue from the appearance of fatty cysts. Additionally, oxaziridine 3 administration to HFD-rats induces antioxidant activity proven by the increase of superoxide dismutase (SOD) and catalase (CAT) activities and the decrease in Thiobarbituric acid reactive substances (TBARS) levels. It also induces the protection of liver-kidney functions confirmed by a decrease in the levels of toxicity parameters in blood.

Protective effect of Sargussum vulgare sulfated polysaccharide against molecular, biochemical and histopathological damage caused by alloxan in experimental diabetic rats

Diabetes is a serious condition that is linked to the development of oxidative stress. In the context of enhancing the biodiversity of Tunisias flora, this study aimed to evaluate the effect of Sargussum vulgare sulfated polysaccharide (SVSP) on hyperglycemia and diabetes complications in the alloxan-induced diabetic rats. Our results showed a disturbance of carbohydrate, lipid, hematological and histopathological parameters, an increase in the α-amylase enzyme activity and damage to the pancreatic, hepatic and renal tissues in rats rendered diabetic by alloxan. In contrast, treatment with SVSP resulted in a correction of fasting and postprandial blood glucose and HbA1c through inhibition of pancreatic α-amylase. We also noticed an improvement in hemogram parameters and an attenuation of the pancreatic oxidative stress markers as well as histological protections. On the other hand, the administration of SVSP to diabetic rats caused, besides the correction of glycemic and lipid parameters, a good defense against hepatotoxicity and nephrotoxicity of diabetes as well as good antioxidant status and histological protections.

Overexpression of AlTMP2 gene from the halophyte grass Aeluropus littoralis in transgenic tobacco enhances tolerance to different abiotic stresses by improving membrane stability and deregulating some stress-related genes

Herein, we report isolation of the AlTMP2 gene from the halophytic C4 grass Aeluropus littoralis. The subcellular localization suggested that AlTMP2 is a plasma membrane protein. In A. littoralis exposed to salt and osmotic stresses, the AlTMP2 gene was induced early and at a high rate, but was upregulated relatively later in response to abscisic acid and cold treatments. Expression of AlTMP2 in tobacco conferred improved tolerance against salinity, osmotic, H2O2, heat, and freezing stresses at the germination and seedling stages. Under control conditions, no growth or yield penalty were mentioned in transgenic plants due to the constitutive expression of AlTMP2. Interestingly, under greenhouse conditions, the seed yield of transgenic plants was significantly higher than that of non-transgenic (NT) plants grown under salt or drought stress. Furthermore, AlTMP2 plants had less electrolyte leakage, higher membrane stability, and lower Na+ and higher K+ accumulation than NT plants. Finally, six stress-related genes were shown to be deregulated in AlTMP2 plants relative to NT plants under both control and stress conditions. Collectively, these results indicate that AlTMP2 confers abiotic stress tolerance by improving ion homeostasis and membrane integrity, and by deregulating certain stress-related genes.

Photosynthesis parameters during acclimatization of in vitro-grown olive plantlets

Monitoring some parameters would help to overcome the difficulties that can affect in vitro-grown plants during the crucial step of their acclimatization. Thus, after the determination of net photosynthesis and other parameters during acclimatization of in vitro-grown olive plantlets, we concluded that three months after the transfer to ex vitro, the in vitro-grown olive plants become well acclimated. In fact, even though the net photosynthesis, relatively high in vitro, recorded low values after 15 d from the transfer, it reverted back to its standard rates after 180 d of acclimatization. Transpiration and stomatal conductance first increased significantly with a maximum of 6.22 mmol(H2O) m−2 s−1 and 1.8 mmol(H2O) m−2 s−1, respectively, but they regressed to very low values after 180 d of acclimatization. Some changes in the leaf anatomy were also observed; the reduction of stomata density and inversely, the increase of trichome density, especially on the abaxial side of the leaves, were observed.