Dietary protein restriction during lactation in primiparous sows with different live weights at farrowing: I. Consequences on sow metabolic status and litter growth

The hypothesis that the restriction of dietary protein during lactation has different impacts on sow metabolic status and milk production according to body weight was evaluated. From 5-months of age until farrowing, the gilts were fed to achieve body weights of 180 or 240 kg at farrowing. At this time, 38 sows were assigned to one of three groups: " 180 kg" sows not restricted in dietary protein during lactation (180CP); "180 kg" restricted in protein (180LP), or "240 kg" sows restricted in protein (240LP). Catheters were fitted in the jugular vein of 24 sows and serial blood samples were collected 1 d before and 1 d after weaning. Amongst the protein-restricted animals, heavy sows (240LP) had a smaller appetite than light sows in early lactation, resulting in lower energy and protein intakes in the 240LP than in the 180LP sows. Body protein losses were 8, 11 and 13.5% of calculated body protein mass at farrowing in the 180CP, 180LP and 240LP sows, respectively. At the end of lactation, IGF-I concentrations were lower in the 180LP than in the sows from the other groups, probably because of the uncoupling between GH and IGF-I secretions. Low IGF-I concentrations likely promote lean tissue mobilization. Glucose and insulin profiles suggested an insulin resistance state in the 240LP sows compared with the 180LP sows, which may explain, at least in part, the lower feed intake and body reserve mobilization in these sows. Plasma pre- and post-prandial concentrations of amino acids in late lactation differed among the three treatment groups. Throughout lactation, litters from the 180LP and 240LP sows had a slower growth rate than litters from sows which were not restricted, suggesting that endogenous protein mobilization throughout lactation does not completely compensate for a low protein intake.     

Dietary protein restriction during lactation in primiparous sows with different live weights at farrowing: II. Consequences on reproductive performance and interactions with metabolic status

The hypothesis that the restriction of dietary protein during lactation has different impacts on reproductive performance in light and heavy sows at farrowing was investigated, as well as the relationships between reproductive parameters and sow metabolic data. At farrowing, 38 primiparous sows were assigned to one of three groups: sows weighing 180 kg not restricted in dietary protein during lactation (180CP); sows weighing 180 or 240 kg restricted in protein (180LP and 240LP). Twenty-four sows were catheterized and serial blood samples were collected 1 d before and 1 d after weaning. The sows were inseminated at the first estrus after weaning and slaughtered at d 30 of gestation. Protein restriction reduced the proportion of sows that returned to estrus within 8 d after weaning in the 180LP sows (P < 0.03), but not in the 240LP sows. It also induced a reduction in ovulation rate in the 180LP sows (P < 0.05) and, to a lesser extent, in the 240LP sows (P = 0.12). When the sows were categorized according to return to estrus (WOI < or = 8 or > 8 d), basal and mean concentrations of LH increased after weaning only in sows with a short WOI. Sows with a delayed estrus exhibited a higher ratio of plasma tyrosine to large neutral amino acids (AA, P < 0.01). In conclusion, large body reserves at farrowing buffer, at least in part, the detrimental effect of a strongly negative nitrogen balance on reproduction. We suggest that the alteration of AA profiles induced by dietary protein restriction and body protein loss alters LH secretion via modifications of the neurotransmitters involved in GnRH secretion.     

Hypercomplexity

What is biological complexity? How many sorts exist? Are there levels of complexity? How are they related to one another? How is complexity related to the emergence of new phenotypes? To try to get to grips with these questions, we consider the archetype of a complex biological system, Escherichia coli. We take the position that E. coli has been selected to survive adverse conditions and to grow in favourable ones and that many other complex systems undergo similar selection. We invoke the concept of hyperstructures which constitute a level of organisation intermediate between macromolecules and cells. We also invoke a new concept, competitive coherence, to describe how phenotypes are created by a competition between maintaining a consistent story over time and creating a response that is coherent with respect to both internal and external conditions. We suggest how these concepts lead to parameters suitable for describing the rich form of complexity termed hypercomplexity and we propose a relationship between competitive coherence and emergence.     

Human beta-globin gene polymorphisms characterized in DNA extracted from ancient bones 12,000 years old.

Analyzing the nuclear DNA from ancient human bones is an essential step to the understanding of genetic diversity in current populations, provided that such systematic studies are experimentally feasible. This article reports the successful extraction and amplification of nuclear DNA from the beta-globin region from 5 of 10 bone specimens up to 12,000 years old. These have been typed for beta-globin frameworks by sequencing through two variable positions and for a polymorphic (AT) chi (T) gamma microsatellite 500 bp upstream of the beta-globin gene. These specimens of human remains are somewhat older than those analyzed in previous nuclear gene sequencing reports and considerably older than those used to study high-copy-number human mtDNA. These results show that the systematic study of nuclear DNA polymorphisms of ancient populations is feasible.     

The nucleo-junctional interplay of the cellular prion protein: A new partner in cancer-related signaling pathways?

The cellular prion protein PrP^c plays important roles in proliferation, cell death and survival, differentiation and adhesion. The participation of PrP^c in tumor growth and metastasis was pointed out, but the underlying mechanisms were not deciphered completely. In the constantly renewing intestinal epithelium, our group demonstrated a dual localization of PrP^c, which is targeted to cell-cell junctions in interaction with Src kinase and desmosomal proteins in differentiated enterocytes, but is predominantly nuclear in dividing cells. While the role of PrP^c in the dynamics of intercellular junctions was confirmed in other biological systems, we unraveled its function in the nucleus only recently. We identified several nuclear PrP^c partners, which comprise γ-catenin, one of its desmosomal partners, β-catenin and TCF7L2, the main effectors of the canonical Wnt pathway, and YAP, one effector of the Hippo pathway. PrP^c up-regulates the activity of the β-catenin/TCF7L2 complex and its invalidation impairs the proliferation of intestinal progenitors. We discuss how PrP^c could participate to oncogenic processes through its interaction with Wnt and Hippo pathway effectors, which are controlled by cell-cell junctions and Src family kinases and dysregulated during tumorigenesis. This highlights new potential mechanisms that connect PrP^c expression and subcellular redistribution to cancer.     

Genetic and Biochemical Characterization of the Phosphoenolpyruvate:Glucose/Mannose Phosphotransferase System of Streptococcus thermophilus

In most streptococci, glucose is transported by the phosphoenolpyruvate (PEP):glucose/mannose phosphotransferase system (PTS) via HPr and IIAB^Man, two proteins involved in regulatory mechanisms. While most strains of Streptococcus thermophilus do not or poorly metabolize glucose, compelling evidence suggests that S. thermophilus possesses the genes that encode the glucose/mannose general and specific PTS proteins. The purposes of this study were to determine (i) whether these PTS genes are expressed, (ii) whether the PTS proteins encoded by these genes are able to transfer a phosphate group from PEP to glucose/mannose PTS substrates, and (iii) whether these proteins catalyze sugar transport. The pts operon is made up of the genes encoding HPr (ptsH) and enzyme I (EI) (ptsI), which are transcribed into a 0.6-kb ptsH mRNA and a 2.3-kb ptsHI mRNA. The specific glucose/mannose PTS proteins, IIAB^Man, IIC^Man, IID^Man, and the ManO protein, are encoded by manL, manM, manN, and manO, respectively, which make up the man operon. The man operon is transcribed into a single 3.5-kb mRNA. To assess the phosphotransfer competence of these PTS proteins, in vitro PEP-dependent phosphorylation experiments were conducted with purified HPr, EI, and IIAB^Man as well as membrane fragments containing IIC^Man and IID^Man. These PTS components efficiently transferred a phosphate group from PEP to glucose, mannose, 2-deoxyglucose, and (to a lesser extent) fructose, which are common streptococcal glucose/mannose PTS substrates. Whole cells were unable to catalyze the uptake of mannose and 2-deoxyglucose, demonstrating the inability of the S. thermophilus PTS proteins to operate as a proficient transport system. This inability to transport mannose and 2-deoxyglucose may be due to a defective IIC domain. We propose that in S. thermophilus, the general and specific glucose/mannose PTS proteins are not involved in glucose transport but might have regulatory functions associated with the phosphotransfer properties of HPr and IIAB^Man.     

Biostratigraphie d’après les foraminifères et paléoenvironnements des séries post-Éocène du sondage ASHTART 28, golfe de Gabès (Tunisie)

The Cenozoic sequence of Ashtart 28 well drilled in the Gulf of Gabes (Tunisia) is the subject of a biostratigraphical study. The samples recovered in cuttings from 390 m and downwards allowed to recognize, above the Late Eocene sediments, a sedimentary series, lithologically diversified, nearly 1600 m thick. Marine Pliocene deposits, generally attesting a low bathymetry, lie unconformably above the Messinian (Oued Bel Khedim formation), which shows the usual features of the Mediterranean confinement. The underlying Messinian pre-evaporitic platform series (Melqart formation), that is over 250 m thick, is typical of a perireefal environment. The sediments assigned to the Tortonian (Somâa Sands formation) are continental and occur unconformably above the approximately 500-metres-thick Middle Miocene strata (Saouaf, Mahmoud, Aïn Grab and Salammbô pars formations). The marine Lower Miocene and Oligocene sediments (Salammbô pars and Ketatna formations), that are more than 300 m thick, lie in continuity under the Middle Miocene. The infralittoral Chattian sequence has especially supplied a diversified assemblage of larger foraminifera recovered in other west-mediterranean basins. Datings were obtained based on planktonic and larger benthic foraminifera (Miogypsinidae, Nummulitidae, Lepidocyclinidae) and by correlations obtained by means of well loggings and lithostratigraphy. Benthic foraminifera, mainly listed for the Miocene and Oligocene, are studied from a systematic, stratigraphic and paleogeographic point of view. The paleoenvironments of deposits are defined for each considered stratigraphic interval. Comparisons are sketched with other drillings of the Gulf of Gabes. Thanks to the numerous data obtained by this detailed study, the Ashtart drilling can serve as a reference for the Tertiary sequence of this part of the Mediterranean domain.