Thermococcus kodakarensis provides a versatile hyperthermophilic archaeal platform for protein expression.

Hyperthermophiles, typically defined as organisms with growth optima ≥80°C, are dominated by the Archaea. Proteins that support life at the extremes of temperatures often retain substantial biotechnological and commercial value, but the recombinant expression of individual hyperthermophilic proteins is commonly complicated in non-native mesophilic hosts due to differences in codon bias, intracellular solutes and the requirement for accessory factors that aid in folding or deposition of metal centers within archaeal proteins. The development of versatile protein expression and facilitated protein purification systems in the model, genetically tractable, hyperthermophilic marine archaeon Thermococcus kodakarensis provides an attractive platform for protein expression within the hyperthermophiles. The assortment of T. kodakarensis genetic backgrounds and compatible selection markers allow iterative genetic manipulations that facilitate protein overexpression and expedite protein purifications. Expression vectors that stably replicate both in T. kodakarensis and Escherichia coli have been validated and permit high-level ectopic gene expression from a variety of controlled and constitutive promoters. Biologically relevant protein associations can be maintained during protein purifications to identify native protein partnerships and define protein interaction networks. T. kodakarensis thus provides a versatile platform for the expression and purification of thermostable proteins.

Maternal dietary omega-3 deficiency worsens the deleterious effects of prenatal inflammation on the gut-brain axis in the offspring across lifetime.

Maternal immune activation (MIA) and poor maternal nutritional habits are risk factors for the occurrence of neurodevelopmental disorders (NDD). Human studies show the deleterious impact of prenatal inflammation and low n-3 polyunsaturated fatty acid (PUFA) intake on neurodevelopment with long-lasting consequences on behavior. However, the mechanisms linking maternal nutritional status to MIA are still unclear, despite their relevance to the etiology of NDD. We demonstrate here that low maternal n-3 PUFA intake worsens MIA-induced early gut dysfunction, including modification of gut microbiota composition and higher local inflammatory reactivity. These deficits correlate with alterations of microglia-neuron crosstalk pathways and have long-lasting effects, both at transcriptional and behavioral levels. This work highlights the perinatal period as a critical time window, especially regarding the role of the gut-brain axis in neurodevelopment, elucidating the link between MIA, poor nutritional habits, and NDD.

Essential omega-3 fatty acids tune microglial phagocytosis of synaptic elements in the mouse developing brain.

Omega-3 fatty acids (n-3 PUFAs) are essential for the functional maturation of the brain. Westernization of dietary habits in both developed and developing countries is accompanied by a progressive reduction in dietary intake of n-3 PUFAs. Low maternal intake of n-3 PUFAs has been linked to neurodevelopmental diseases in Humans. However, the n-3 PUFAs deficiency-mediated mechanisms affecting the development of the central nervous system are poorly understood. Active microglial engulfment of synapses regulates brain development. Impaired synaptic pruning is associated with several neurodevelopmental disorders. Here, we identify a molecular mechanism for detrimental effects of low maternal n-3 PUFA intake on hippocampal development in mice. Our results show that maternal dietary n-3 PUFA deficiency increases microglia-mediated phagocytosis of synaptic elements in the rodent developing hippocampus, partly through the activation of 12/15-lipoxygenase (LOX)/12-HETE signaling, altering neuronal morphology and affecting cognitive performance of the offspring. These findings provide a mechanistic insight into neurodevelopmental defects caused by maternal n-3 PUFAs dietary deficiency.

Dietary omega-3 deficiency exacerbates inflammation and reveals spatial memory deficits in mice exposed to lipopolysaccharide during gestation.

Maternal immune activation (MIA) is a common environmental insult on the developing brain and represents a risk factor for neurodevelopmental disorders. Animal models of in utero inflammation further revealed a causal link between maternal inflammatory activation during pregnancy and behavioural impairment relevant to neurodevelopmental disorders in the offspring. Accumulating evidence point out that proinflammatory cytokines produced both in the maternal and fetal compartments are responsible for social, cognitive and emotional behavioral deficits in the offspring. Polyunsaturated fatty acids (PUFAs) are essential fatty acids with potent immunomodulatory activities. PUFAs and their bioactive derivatives can promote or inhibit many aspects of the immune and inflammatory response. PUFAs of the n-3 series ('n-3 PUFAs', also known as omega-3) exhibit anti-inflammatory/pro-resolution properties and promote immune functions, while PUFAs of the n-6 series ('n-6 PUFAs' or omega-6) favor pro-inflammatory responses. The present study aimed at providing insight into the effects of n-3 PUFAs on the consequences of MIA on brain development. We hypothesized that a reduction in n-3 PUFAs exacerbates both maternal and fetal inflammatory responses to MIA and later-life defects in memory in the offspring. Based on a lipopolysaccharide (LPS) model of MIA (LPS injection at embryonic day 17), we showed that n-3 PUFA deficiency 1) alters fatty acid composition of the fetal and adult offspring brain; 2) exacerbates maternal and fetal inflammatory processes with no significant alteration of microglia phenotype, and 3) induces spatial memory deficits in the adult offspring. We also showed a strong negative correlation between brain content in n-3 PUFA and cytokine production in MIA-exposed fetuses. Overall, our study is the first to address the deleterious effects of n-3 PUFA deficiency on brain lipid composition, inflammation and memory performances in MIA-exposed animals and indicates that it should be considered as a potent environmental risk factor for the apparition of neurodevelopmental disorders.

Nutritional n-3 PUFAs deficiency during perinatal periods alters brain innate immune system and neuronal plasticity-associated genes.

Low dietary intake of the n-3 polyunsaturated fatty acids (PUFAs) is a causative factor of neurodevelopmental disorders. However the mechanisms linking n-3 PUFAs low dietary intake and neurodevelopmental disorders are poorly understood. Microglia, known mainly for their immune function in the injured or infected brain, have recently been demonstrated to play a pivotal role in regulating maturation of neuronal circuits during normal brain development. Disruption of this role during the perinatal period therefore could significantly contribute to psychopathologies with a neurodevelopmental neurodevelopmental component. N-3 PUFAs, essential lipids and key structural components of neuronal membrane phospholipids, are highly incorporated in cell membranes during the gestation and lactation phase. We previously showed that in a context of perinatal n-3 PUFAs deficiency, accretion of these latter is decreased and this is correlated to an alteration of endotoxin-induced inflammatory response. We thus postulated that dietary n-3 PUFAs imbalance alters the activity of microglia in the developing brain, leading to abnormal formation of neuronal networks. We first confirmed that mice fed with a n-3 PUFAs deficient diet displayed decreased n-3 PUFAs levels in the brain at post-natal days (PND)0 and PND21. We then demonstrated that n-3 PUFAs deficiency altered microglia phenotype and motility in the post-natal developing brain. This was paralleled by an increase in pro-inflammatory cytokines expression at PND21 and to modification of neuronal plasticity-related genes expression. Overall, our findings show for the first time that a dietary n-3 PUFAs deficiency from the first day of gestation leads to the development of a pro-inflammatory condition in the central nervous system that may contribute to neurodevelopmental alterations.

[Purgative activity of Cassia italica]. / Contribution à l'étude de l'activité purgative de Cassia italica.

Twenty guinea pigs were used to study the effects of Cassia italica leaves and pods extracts on intestinal motricity in vitro. The results obtained showed that the plant stimulate intestinal contractions with dose-dependent relation. Moreover, Cassia italica contractile activity was comparable to the acetylcholine one and was inhibited by atropine. According to these results, Cassia italica purgative activity is supported at least, by it's stimulating effect on intestinal motricity.

[Antihypertensive action of Parkia biglobosa+ (Jacq) Benth seeds in the rat]. / Etude de l'action antihypertensive des graines de Parkia biglobosa (Jacq). Benth chez le rat.

Hundred white Wistar rats have been used to evaluate the antihypertensive effects of entire seeds and decorticated, fermented seeds of a soudanian plant, Parkia biglobosa. The arterial blood pressure was measured by using bloody method in anesthizied animals. The Pham Huu Chanh method was used to determine type plant's antihypertensive activity. According to the results obtained, in both preparations, adequate doses decrease arterial blood pressure, diastolic more than systolic, but the effect of fermented seeds was more important than the entire seeds. In the two cases, the decrease in blood pressure is greated in hypertensive than in normotensive subjects, and the hypotension induced was well correlated with a bradycardia.

[Choleretic effects of Cassia alata Linn in the rat]. / Etude de l'activité cholérétique de Cassia alata Linn chez le rat.

Fifty rats weighing average 200 g were used to study choleretic activity of Cassia alata LINN extract. Bile was collected according to acute biliarly fistula technic on animals anesthetized with 1.5g/kg of ethyle carbamate (Urethane ND). After determination of the minimal active dose (15 mg/kg) and lethal dose (100mg/kg) of the extract, rats were allowed in 5 groups of 10 each one: one reference group, one group receiving 15 mg/kg of Hydroxycyclohexenyl-butyrate (Hebecol ND) a synthetic choleretic, and 3 groups receiving respectively 15 mg/kg, 30 mg/kg and 60 mg/kg of Cassia alata extract. According to results obtained, choleretic activity of Cassia alata at 15 mg/kg is better than the Hebucol ND ones. But at elevated doses, the plant tend to inhibit bile secretion.

[Influence of dietary calcium/phosphorus ratio on blood calcium, phosphate and magnesium during gestation in the rabbit]. / Influence du rapport calcium/phosphore de la ration sur la calcémie, la phosphatémie et la magnésémie de la lapine en gestation.

Sixteen Thiès strain rabbits were used to study the effect of the calcium/phosphorus ratio on plasma calcium, inorganic phosphorus and magnesium levels during pregnancy. Animals were allocated in 2 groups of 8: one receiving a diet with a Ca/P ratio of 1:0 and the other a diet with Ca/P ratio of 2:1. Water was given ad libitum for all rabbits. Results obtained showed that Ca blood level was significantly higher in rabbits receiving the diet with Ca/P ratio of 2:1 before covering and during the first week of pregnancy. During the last 15 d of pregnancy, Ca blood level decreased significantly in the 2 groups of animals. Plasma inorganic phosphorus and magnesium levels were not significantly different in the 2 groups of rabbits until the 2nd wk of pregnancy. But at the end of pregnancy, while phosphatemia and magnesemia decreased in rabbits fed a high Ca/P ratio, in the other group these parameters remained unchanged.

[Influence of the season and of gestation on the plasma concentration of thyroid hormones: triiodothyronine (T3) and thyroxine (T4) in Sahel Peulh ewes]. / Influence de la saison et de la gestation sur la concentration plasmatique des hormones thyroïdiennes: triiodothyronine (T3) et thyroxine (T4), chez la brebis peulh du Sahel.

Seasonal and gestational variations of triiodothyronine (T3) and thyroxine (T4) plasma concentrations were evaluated in 12 pregnant and 6 non pregnant adult Sahel Peulh ewes. Blood samples were drawn from all animals at different dates for radio-immunoassay. In this particular breed of sheep, plasma triiodothyronine and thyroxine levels did not present significant variations from the beginning of the cool season (December) until the end of the dry warm season (May). On the contrary, a highly significant rise of hormones (P less than 0.01) was observed at the onset of the humid warm season (June). Moreover, a significant decrease of thyroid hormone plasma levels (P less than or equal to 0.05) greater for thyroxine than triiodothyronine was observed at the end of gestation, particularly in twin pregnancies. At birth, the thyroxine plasma level was higher in single than in twin lambs (139.6 +/- 66.5 vs 110.5 +/- 43.8 ng/ml).