Differences in fatty acid metabolisms in domestic animals: some dilemmas and ideas to address body composition and obesity control

Relatively high amounts of fats or oils (mayor que 40-50 g/kg diet) are frequently used in animal nutrition. Vegetables oils are richer in polyunsaturated fatty acids than animal fats. Most of the works studying the effect of different dietary fat sources are focused either on the existing differences on fat digestibility depending on their fatty acid composition (Wiseman et al., 1991) or on their effect on the carcass fat fatty acid profile (Sanz et al., 1999a). lnformation regarding the effect of dietary fat saturation on fat utilization and deposition it is more limited. lt is generally assumed that, apart from differences in digestion, fatty acids of different composition are equally used for metabolic purposes.

Reproductive long-term effects, endocrine response and fatty acid profile of rabbit does fed diets supplemented with n-3 fatty acids

The effect of a diet enriched with polyunsaturated n -3 fatty acids (PUFA) on endocrine, reproductive, and productive responses of rabbit females and the litters has been studied. Nulliparous does ( n = 125) were fed ad libitum from rearing to second weaning two diets supplemented with different fat sources: 7.5 g/kg lard for the control diet (group C; n = 63) or 15 g/kg of a commercial supplement containing a 50% ether extract and 35% of total fatty acids (FAs) as PUFA n -3 (Group P; n = 62). Dietary treatments did not affect apparent digestibility coefficients of nutrients, or reproductive variables of does including milk pro- duction, mortality and average daily gain of kits over two lactations. However, on Day 5 and 7 post-induction of ovulation, progesterone of Group P tended to increase to a greater extent than in does of Group C. Total PUFAs, n -6 and n -3 and eicosapentanoic (EPA) contents were greater in adipose tissues of does in Group P than in Group C. Docosapentaenoic acid (DPA), EPA, and docosahexaenoic acid (DHA) concentrations were greater in peri-ovarian than in scapular fat with abdominal fat being intermediate in concentration. In PUFA sup- plemented does, kit mortality at the second parturition tended to be less than in control does. Also, kits born to does of the PUFA-supplemented group weighed more and were of greater length than from does of control group. In conclusion, effectiveness of dietary intervention on reproductive and performance response is greater in the second parity, which suggests an accumulative long-term beneficial effect of n -3 FA supplementation in reproductive rabbit does

Study of the influence of actin-binding proteins using linear analyses of cell deformability

The actin cytoskeleton plays a key role in the deformability of the cell and in mechanosensing. Here we analyze the contributions of three major actin cross-linking proteins, myosin II, a-actinin and filamin, to cell deformability, by using micropipette aspiration of Dictyostelium cells. We examine the applicability of three simple mechanical models: for small deformation, linear viscoelasticity and drop of liquid with a tense cortex; and for large deformation, a Newtonian viscous fluid. For these models, we have derived linearized equations and we provide a novel, straightforward methodology to analyze the experiments. This methodology allowed us to differentiate the effects of the cross-linking proteins in the different regimes of deformation. Our results confirm some previous observations and suggest important relations between the molecular characteristics of the actin-binding proteins and the cell behavior: the effect of myosin is explained in terms of the relation between the lifetime of the bond to actin and the resistive force; the presence of a-actinin obstructs the deformation of the cytoskeleton, presumably mainly due to the higher molecular stiffness and to the lower dissociation rate constants; and filamin contributes critically to the global connectivity of the network, possibly by rapidly turning over crosslinks during the remodeling of the cytoskeletal network, thanks to the higher rate constants, flexibility and larger size. The results suggest a sophisticated relationship between the expression levels of actinbinding proteins, deformability and mechanosensing.

Palaeoenvironmental reconstruction of Las Conchas Mire (Asturias, N. Spain) from the ketone and fatty acid record= reconstrucción paleoambiental de la Turbera de las Conchas (Asturias, N. España)a partir del registro de cetonas y ácidos grasos

Se han estudiado los biomarcadores, principalmente cetonas y ácidos, preservados en el registro de 3.2 m de la Turbera de Las Conchas. Las cetonas reflejan cierta actividad bacteriana desde 94 cm hasta la base del registro, Los ácidos grasos reflejan una buena preservación de la materia orgánica, salvo en los 20 cm superiores en los que hay indicios de oxidación microbiana de alcanos .The biomarkers, mainly ketones and fally aclds, preserved In 3.2 m deep Las Conchas Mire have been studied, Kelones reflect certain bacterial activity from 94 cm to the bottom of the record. Falty aclds indlcate a good preservation of the organlc matter, wlth the exception of the uppermost 20 cm In whlch mlcroblal oxldation of alkanes are likely to occur