Calorie restriction (CR) is the most robust non-genetic intervention to delay aging. However, there are a number of emerging experimental variables that alter CR responses. We investigated the role of sex, strain, and level of CR on health and survival in mice. CR did not always correlated with lifespan extension, though it consistently improved health across strains and sexes. Transcriptional and metabolomics changes driven by CR in liver indicated anaplerotic filling of the Krebs cycle together with fatty acid fueling of mitochondria. CR prevented age-associated decline in the liver proteostasis network while increasing mitochondrial number, preserving mitochondrial ultrastructure and function with age. Abrogation of mitochondrial function negated life-prolonging effects of CR in yeast and worms. Our data illustrate the complexity of CR in the context of aging, with a clear separation of outcomes related to health and survival, highlighting complexities of translation of CR into human interventions.

Summary Increased expression of SIRT1 extends the lifespan of lower organisms and delays the onset of age-related diseases in mammals. Here, we show that SRT2104, a synthetic small molecule activator of SIRT1, extends both mean and maximal lifespan of mice fed a standard diet. This is accompanied by improvements in health, including enhanced motor coordination, performance, bone mineral density and insulin sensitivity associated with higher mitochondrial content and decreased inflammation. Short-term SRT2104 treatment preserves bone and muscle mass in an experimental model of atrophy. These results demonstrate it is possible to design a small molecule that can slow aging and delay multiple age-related diseases in mammals, supporting the therapeutic potential of SIRT1 activators in humans.

Hypocotyls of kidney beans (Phaseolus vulgaris L.) accumulated ascorbate after preincubation with a number of possible precursors, mainly L-galactono-␥-lactone (L-GL) and L-gulono-␥-lactone. The increase in the intracellular ascorbate concentration was parallel to the high stimulation of the L-GL dehydrogenase (L-GLD) activity measured in vitro using L-GL as a substrate and cytochrome c as an electron acceptor. Cell fractionation using a continuous linear Percoll gradient demonstrated that L-GLD is associated with mitochondria; therefore, pure mitochondria were isolated and subjected to detergent treatment to separate soluble from membrane-linked proteins. L-GLD activity was mainly associated with the detergent phase, suggesting that a membrane-intrinsic protein is responsible for the ascorbic acid biosynthetic activity. Subfractionation of mitochondria demonstrated that L-GLD is located at the inner membrane.

A new myosin motor-like chitin synthase gene, chsVb, has been identified in the vascular wilt fungus Fusarium oxysporum f. sp. lycopersici. Phylogenetic analysis of the deduced amino acid sequence of the chsVb chitin synthase 2 domain (CS2) revealed that ChsVb belongs to class VII chitin synthases. The ChsVb myosin motor-like domain (MMD) is shorter than the MMD of class V chitin synthases and does not contain typical ATP-binding motifs. Targeted disrupted single (⌬chsVb) and double (⌬chsV ⌬chsVb) mutants were unable to infect and colonize tomato plants or grow invasively on tomato fruit tissue. These strains were hypersensitive to compounds that interfere with fungal cell wall assembly, produced lemon-like shaped conidia, and showed swollen balloon-like structures in hyphal subapical regions, thickened walls, aberrant septa, and intrahyphal hyphae. Our results suggest that the chsVb gene is likely to function in polarized growth and confirm the critical importance of cell wall integrity in the complex infection process of this fungus.In order to establish successful infection, fungal pathogens must overcome highly effective, constitutive physical and chemical barriers, employing a range of different infection strategies. These strategies may be specific to a particular fungal species according to the nature of the host surface, and within a single species, they may depend on the type of spores initiating the infection process. A number of important steps in the infection process are common to all strategies, including adhesion to the surface of the plant, penetration of the plant surface, and acquisition of nutrients from the plant cells (18). Hyphae of plant and animal pathogenic filamentous fungi navigate on the underlying surface topography by thigmotropism in order to locate points of weakened surface integrity to gain vulnerable sites for invasion (18,15). These sites are penetrated mechanically by expansion of the growing hyphal tips. Furthermore, fungal hyphae have been predicted to resist, at their tips, an opposing resistant force exerted by 8% (wt/vol) agar (28). These forces are related to the cell turgor pressure acting against the surface of a substrate at cell expansion places. Thus, fungal morphogenesis is an essential component for host invasion (16) and, at the same time, for establishing the correct fungal cell wall biogenesis.Chitin, a microfibrillar ␤-1,4-linked homopolymer of N-acetylglucosamine (GlcNAc) (5), is considered to be a relatively minor but structurally important component of fungal cell walls. While in yeast (Saccharomyces cerevisiae), chitin constitutes 1 to 2% of the total dry weight, for filamentous fungi, the chitin content has been reported to reach up to 10 to 20% (5). Chitin seems to be present in all eukaryote kingdoms except Plantae. Thus, chitin and its biosynthesis are potentially interesting targets for the discovery of novel fungicides against phytopathogenic fungi. Chitin synthesis on the plasma membrane occurs by the extrusion of nascent chains into the cell wall ...

We analyzed ultrastructural changes and markers of fission/fusion in hepatocyte mitochondria from mice submitted to 40% calorie restriction (CR) for 6 months versus ad-libitum-fed controls. To study the effects of dietary fat under CR, animals were separated into three CR groups with soybean oil (also in controls), fish oil, and lard. CR induced differential changes in hepatocyte and mitochondrial size, in the volume fraction occupied by mitochondria, and in the number of mitochondria per hepatocyte. The number of cristae per mitochondrion was significantly higher in all CR groups compared with controls. Proteins related to mitochondrial fission (Fis1 and Drp1) increased with CR, but no changes were detected in proteins involved in mitochondrial fusion (Mfn1, Mfn2, and OPA1). Although many of these changes could be attributed to CR regardless of dietary fat, changing membrane lipid composition by different fat sources did modulate the effects of CR on hepatocyte mitochondria.