Effect of seed on ripening control components during avocado fruit development

Seedless avocado fruit are produced alongside seeded fruit in the cultivar Arad, and both reach maturity at the same time. Using this system, it was possible to show that avocado seed inhibits the ripening process: seedless fruits exhibited higher response to exogenous ethylene already at the fruitlet stage, and also at the immature and mature fruit stages. They produced higher CO₂ levels, and the ethylene peak was apparent at the fruitlet stage of seedless fruit, but not of seeded ones. The expression levels of PaETR, PaERS1 and PaCTR1 on the day of harvest at all developmental stages were very similar between seeded and seedless fruit, except that PaCTR1 was higher in seedless fruit only at very early stages. This expression pattern suggests that the seed does not have an effect on components of the ethylene response pathway when fruits are just picked. The expression of MADS-box genes, PaAG1 and PaAGL9, preceded the increase in ethylene production of mature seeded fruit, but not at earlier stages. However, only PaAGL9 was induced in seedless fruit at early stages of development. Taken together, these data suggest that these genes are perhaps involved in climacteric response in seeded fruit, and the seed is responsible for their induction at normal fruit ripening.     

Capzb2 Interacts with β-Tubulin to Regulate Growth Cone Morphology and Neurite Outgrowth

Capping protein (CP) is a heterodimer that regulates actin assembly by binding to the barbed end of F-actin. In cultured nonneuronal cells, each CP subunit plays a critical role in the organization and dynamics of lamellipodia and filopodia. Mutations in either α or β CP subunit result in retinal degeneration in Drosophila. However, the function of CP subunits in mammalian neurons remains unclear. Here, we investigate the role of the β CP subunit expressed in the brain, Capzb2, in growth cone morphology and neurite outgrowth. We found that silencing Capzb2 in hippocampal neurons resulted in short neurites and misshapen growth cones in which microtubules overgrew into the periphery and completely overlapped with F-actin. In searching for the mechanisms underlying these cytoskeletal abnormalities, we identified β-tubulin as a novel binding partner of Capzb2 and demonstrated that Capzb2 decreases the rate and the extent of tubulin polymerization in vitro. We mapped the region of Capzb2 that was required for the subunit to interact with β-tubulin and inhibit microtubule polymerization. A mutant Capzb2 lacking this region was able to bind F-actin and form a CP heterodimer with α2-subunit. However, this mutant was unable to rescue the growth cone and neurite outgrowth phenotypes caused by Capzb2 knockdown. Together, these data suggest that Capzb2 plays an important role in growth cone formation and neurite outgrowth and that the underlying mechanism may involve direct interaction between Capzb2 and microtubules.     

26 Development of the cultivation of Laminaria Saccharina as the extractive inorganic component of an integrated aquaculture system and monitoring of therapeutants and phycotoxins

The development of sustainable integrated aquaculture systems requires combining fed aquaculture (finfish) with extractive inorganic aquaculture (seaweed) and extractive organic aquaculture (shellfish). With the support of AquaNet, the Network of Centers of Excellence in Aquaculture in Canada, we are developing such a system at an industrial pilot scale by co‐cultivating salmon (Salmo salar), kelp (Laminaria saccharina) and blue mussel (Mytilus edulis) at aquaculture sites in the Bay of Fundy, Canada. This presentation will focus on the development of the extractive inorganic component. The entire cycle of rearing Laminaria saccharina has been completed and improved, both in the laboratory and at the integrated sites: release in the laboratory of spores from mature macroscopic sporophytes, seeding of ropes, germination of microscopic gametophytes, sexual maturation of male and female gametophytes, development of zygotes into juvenile sporophytes, which are then transplanted to the sites for rapid grow‐out. Another aspect of the project, food safety monitoring of chemical therapeutants and phycotoxins in mussel and kelp cultured in proximity to salmon, will also be described. The productivity, nutrient absorption capacity, and role of the seaweed component are being analyzed so that its appropriate scale to the other components can be defined in order to develop responsible aquaculture practices in which metabolic/physiological processes of the different co‐cultured organisms counter‐balance each other within acceptable operational limits. Adopting polytrophic strategies will be key to the aquaculture industry to develop its environmentally and economically‐balanced diversification and increase its social acceptability within a broader coastal management framework.     

TAT‐MTS‐MCM fusion proteins reduce MMA levels and improve mitochondrial activity and liver function in MCM‐deficient cells

Methylmalonic aciduria (MMA) is a disorder of organic acid metabolism resulting from a functional defect of the mitochondrial enzyme, methylmalonyl‐CoA mutase (MCM). The main treatments for MMA patients are dietary restriction of propiogenic amino acids and carnitine supplementation. Liver or combined liver/kidney transplantation has been used to treat those with the most severe clinical manifestations. Thus, therapies are necessary to help improve quality of life and prevent liver, renal and neurological complications. Previously, we successfully used the TAT‐MTS‐Protein approach for replacing a number of mitochondrial‐mutated proteins. In this targeted system, TAT, an 11 a.a peptide, which rapidly and efficiently can cross biological membranes, is fused to a mitochondrial targeting sequence (MTS), followed by the mitochondrial mature protein which sends the protein into the mitochondria. In the mitochondria, the TAT‐MTS is cleaved off and the native protein integrates into its natural complexes and is fully functional. In this study, we used heterologous MTSs of human, nuclear‐encoded mitochondrial proteins, to target the human MCM protein into the mitochondria. All fusion proteins reached the mitochondria and successfully underwent processing. Treatment of MMA patient fibroblasts with these fusion proteins restored mitochondrial activity such as ATP production, mitochondrial membrane potential and oxygen consumption, indicating the importance of mitochondrial function in this disease. Treatment with the fusion proteins enhanced cell viability and most importantly reduced MMA levels. Treatment also enhanced albumin and urea secretion in a CRISPR/Cas9‐engineered HepG2 MUT (‐/‐) liver cell line. Therefore, we suggest using this TAT‐MTS‐Protein approach for the treatment of MMA.     

Comparative transcript profiling of a peach and its nectarine mutant at harvest reveals differences in gene expression related to storability

Gene expression at harvest was compared for two stone fruit cultivars, a peach and its near-isogenic nectarine mutant, using two microarray platforms, μPEACH1.0 and ChillPeach. Together, both platforms covered over 6,000 genes out of which 417 were differentially expressed between the fruits of the two cultivars at a p value of 0.05. A total of 47 genes in nectarine and 60 genes in peach were at least twofold higher relative to each other. Nectarine had much better storage characteristics than peach and could be stored for over 5 weeks at 5 °C without storage disorders. In an attempt to determine whether gene expression at harvest could give an indication of storage potential, the expression analysis of the two cultivars was compared to that of two genotypes with different sensitivities to chilling injury. Principal component analysis of gene expression results across four fruit types differing in chilling sensitivity resulted in 41 genes whose expression levels separated the fruits according to sensitivity to storage disorders, suggesting that the genes have a role in cold response adaptation.     

Paralytic shellfish toxins in zooplankton, mussels, lobsters and caged Atlantic salmon, Salmo salar, during a bloom of Alexandrium fundyense off Grand Manan Island, in the Bay of Fundy

Substantial mortalities of Atlantic salmon (Salmo salar) at two aquaculture sites in Long Island Sound, off Grand Manan Island, Bay of Fundy (BoF) (New Brunswick, Canada) in September 2003, were associated with a bloom of Alexandrium fundyense (>3 × 10⁵ cells L⁻¹), a dinoflagellate alga that produces toxins which cause paralytic shellfish poisoning (PSP). Cells of A. fundyense collected from surface waters while fish were dying had total paralytic shellfish (PS) toxin concentrations of 70.6 pg STX equiv. (saxitoxin equivalents) cell⁻¹ and PS toxin profiles rich in carbamate toxins (78.2%). The zooplankton sampled contained PS toxins (63.1 pg STX equiv. g⁻¹ wet wt) and the toxin profile matched that of A. fundyense cells.Mean PS toxin levels were low (<4 μg STX equiv. 100 g⁻¹ wet wt) in stomach, gill and muscle tissues of moribund salmon, suggesting that PS toxins are very lethal to salmon.The PS toxin concentrations in blue mussels (Mytilus edulis) growing on the salmon cages (37; 526 μg STX equiv. 100 g⁻¹ wet wt) were the highest recorded to date from this region. Their PS toxin profiles showed enhanced carbamate contents (85.5%) compared with that found in A. fundyense. Blue mussels collected from an adjacent Canadian Food Inspection Agency (CFIA) monitoring site in Grand Manan had PS toxin concentrations of 4214 and 150 μg STX equiv. 100 g⁻¹ wet wt in late September and December, respectively, well above the regulatory limit (RL), and horse mussels (Modiolus modiolus) collected in late September had PS toxin concentrations of 2357 μg STX equiv. 100 g⁻¹ wet wt. Detoxification under laboratory conditions suggested that blue mussels may require up to 19 weeks for elimination below RL when they accumulate these high concentrations of PS toxins. This depuration period may be shorter in the field.PS toxin levels above RL were detected in hepatopancreatic tissues of lobster (Homarus americanus), with lower levels (<16 μg STX equiv. 100 g⁻¹ wet wt) in tail muscle and gills.These results illustrate the movement of PS toxins through the marine food chain following an A. fundyense bloom in the BoF, and support earlier studies suggesting that kills from the region of zooplanktivorous fish, such as herring (Clupea harengus harengus), can be attributed to blooms of A. fundyense. This is the first reported incident of PSP associated with mortalities of caged Atlantic salmon in the BoF. Analyses of muscle tissues and viscera from the affected salmon indicated that any portion would not be a health hazard if consumed.     

A comparison of olanzapine and risperidone on the risk of psychiatric hospitalization in the naturalistic treatment of patients with schizophrenia

BACKGROUND: Decreasing hospital admissions is important for improving outcomes for people with schizophrenia and for reducing cost of hospitalization, the largest expenditure in treating this persistent and severe mental illness. This prospective observational study compared olanzapine and risperidone on one-year psychiatric hospitalization rate, duration, and time to hospitalization in the treatment of patients with schizophrenia in usual care. METHODS: We examined data of patients newly initiated on olanzapine (N = 159) or risperidone (N = 112) who continued on the index antipsychotic for at least one year following initiation. Patients were participants in a 3-year prospective, observational study of schizophrenia patients in the US. Outcome measures were percent of hospitalized patients, total days hospitalized per patient, and time to first hospitalization during the one-year post initiation. Analyses employed a generalized linear model with adjustments for demographic and clinical variables. A two-part model was used to confirm the findings. Time to hospitalization was measured by the Kaplan-Meier survival formula. RESULTS: Compared to risperidone, olanzapine-treated patients had significantly lower hospitalization rates, (24.1% vs. 14.4%, respectively, p = 0.040) and significantly fewer hospitalization days (14.5 days vs. 9.9 days, respectively, p = 0.035). The mean difference of 4.6 days translated to $2,502 in annual psychiatric hospitalization cost savings per olanzapine-treated patient, on average. CONCLUSIONS: Consistent with prior clinical trial research, treatment-adherent schizophrenia patients who were treated in usual care with olanzapine had a lower risk of psychiatric hospitalization than risperidone-treated patients. Lower hospitalization costs appear to more than offset the higher medication acquisition cost of olanzapine.