Starch granule size variation and relationship with tuber dry matter content in heritage potato varieties

Heritage potato varieties in Canada are historic old varieties collected from Canada and various countries before the formal establishment of the Canadian plant variety registration system and may be a valuable gene resource for beneficial traits in potato breeding and bioproducts development. Greater evaluation is the key for the enhanced use of these materials. It is unknown how much variation of starch granules occurs among Canadian heritage potato varieties. We analyzed the starch granule size of 14 potato heritage varieties held in the Canadian Plant Gene Resources collection over 2 years using a squeezed juice and microscopic method recently developed at the Potato Research Centre. The varieties demonstrated considerable variation in starch granule size and shape. The granules showed average lengths ranging from 18 μm in the variety Congo to 32 μm in ‘Russet Burbank’. The largest single granule measured from 64 μm in ‘Congo’ to 91 μm in ‘Crotte d’Ours.’ The granule sizes of the varieties showed a very high correlation (r = 0.975, P < 0.0001) between years. This high reproducibility suggests the existence of genetic factors in determining starch granule size. We also found that the starch granule size is positively correlated with tuber dry matter (in terms of specific gravity) in these heritage potatoes. The results demonstrated reproducible genotypic variation for starch granule size and shape in tubers with a significant correlation to tuber dry matter in these heritage potato varieties, and offers the possibility for and agronomic relevance of genetic modification of starch granules through selective breeding.     

In vitro digestibility of α-casozepine, a benzodiazepine-like peptide from bovine casein, and biological activity of its main proteolytic fragment

α-Casozepine is a peptide, corresponding to the sequence 91-100 of the bovine α(s1)-casein, displaying anxiolytic activity in the rat. The α(s1)-casein tryptic hydrolysate containing this peptide decreases stress effects after oral administration in various species including man. Therefore, the stability of this peptide toward gastric and pancreatic proteases has been assessed by using pepsin, chymotrypsin/trypsin, Corolase PP, pepsin followed by chymotrypsin/trypsin or pepsin followed by Corolase PP. α-Casozepine was slowly degraded by chymotrypsin, much more sensitive to pepsin and Corolase PP but not completely destroyed after 4 h kinetics. The bonds in the region 91 to 95 of the α-casozepine were totally resistant to hydrolysis by all studied proteases. Surprisingly, a fragment, corresponding to the sequence 91-97 and found in all the hydrolysis media in significant amount, possessed an anxiolytic activity in three behavioral tests measuring this parameter. This peptide could participate in the in vivo activity of α-casozepine.     

Effect of cis/trans isomerism of beta-carotene on the ratios of volatile compounds produced during oxidative degradation

beta-Carotene is, when cleaved, an important source of flavor and aroma compounds in fruits and flowers. Among these aroma compounds, the main degradation products are beta-ionone, 5,6-epoxy-beta-ionone, and dihydroactinidiolide (DHA), which are associated by flavorists and perfumers with fruity, floral, and woody notes. These three species can be produced by degradation of beta-carotene through an attack by enzyme-generated free radicals and a cleavage at the C9-C10 bond. This study investigated the influence of cis/trans isomerism at the C9-C10 bond on the production of beta-carotene degradation compounds, first with a predictive approach and then experimentally with different isomer mixtures. beta-Carotene solutions containing high ratios of 9-cis-isomers produced more DHA, suggesting a different pathway than for the transformation of all-trans-beta-carotene to ionone and DHA. These results are important in the search for financially viable processes to produce natural carotene-derived aroma compounds.     

Geographical distribution of Alzheimer's disease cases at birth and the geochemical profile of Saguenay-Lac-Saint-Jean/Québec,Canada (image project)

Accepting as founded the hypothesis of a multifactorial origin for the Alzheimer's disease (AD), we explore the possible links between the geographical distribution of AD cases according to their birth place and the geochemical profile of the Saguenay-Lac-Saint-Jean (SLSJ) territory in the province of Québec. The method used for factor analysis of correspondances (FAC) and another one based on the differences between the residential and municipal geochemical concentrations (DRMC) have been used for this purpose. The geochemical matrix of SLSJ relates the highest concentrations of nickel, copper and zinc to the sector surrounding the Jonquière municipality. Moreover, high concentrations of iron, lead and manganese were found in the northern sector of the Lac Saint-Jean. The DRMC method corroborates this strong correlation between iron, lead and manganese. Furthermore, these concentrations do not differ from the north-american geochemical standards. No single geochemical element seems to be associate with the spatial distribution of cases. It is, however, still possible that a certain synergistic effect between two or several elements could be implied in the development of the disease. According to the results of the soil analysis, there does not seem to be any association between the spatial distribution of cases and the concentration of aluminum, a chemical element that has been thought to be implied in the etiology of AD. These results are compared with those obtained by other workers in the micronesian islands, where abnormally high frequencies of amyotrophic lateral sclerosis and parkinsonism dementia have already been observed.     

Detailed physicochemical characterization of the 2S storage protein from rape (Brassica napus L.)

Chromatographic, chemical, and spectroscopic techniques were used to characterize the physicochemical properties of napin purified by preparative chromatography. The molar extinction coefficient was determined (epsilon = 0.56), and static and dynamic light scattering measurements enabled the average molecular weight (M(w) = 13919), the second virial coefficient (A(2) = 23.95 x 10(-)(5) mol cm(3) g(-)(2)), and the hydrodynamic radius (R(H) = 1.98 nm) to be determined. No conformational changes were observed by fluorescence and circular dichroism measurements in different buffers at pH 3, 4.6, 7, and 12, confirming the high pH stability of this protein. From MALDI-TOF analysis and after enzymatic digestion, it was found that this purified sample, extracted from the rapeseed variety Express, contained mainly isoform 2SS3_BRANA.     

Fatty acid distribution in muscle,liver, and gonads of rays (Dasyatis marmorata,Rhinobatos cemiculus,and Rhinoptera marginata) from the East Tropical Atlantic Ocean

If a great number of rays are fished in the Tropical East Atlantic Ocean for their caudal fins, only a small amount of ray flesh is processed. Among them, three species of rays, Dasyatis marmorata, Rhinobatos cemiculus, and Rhinoptera marginata, from the Mauritanian coast have been investigated for the fatty acid composition of their lipids. Gas chromatography and gas chromatography-mass spectrometry allowed identification of 50 molecules from muscles, livers, and gonads of these fishes. Principal component analysis, starting from >50 samples, reveals significant differences in various fatty acid distributions, related to the species and sex of the sampled fish. Some of them are preferentially present in one sex or in both species, whereas the occurrence of others characterizes the male and female of one or two species. The results show that rays are potential resources of polyunsaturated fatty acids (PUFA) and should be used in the diet of local populations. The lipidic fractions contained a high amount of PUFA (up to 30% of the total), mainly composed of docosa-4,7,10,13,16,19-hexaenoic acid, eicosa-5,8,11,14-tetraenoic acid, and eicosa-5,8,11,14,17-pentaenoic acid.     

Main routes of oxygen ingress through different closures into wine bottles

The main routes of oxygen ingress into wine bottles through "technical" cork stoppers (Neutrocork), natural cork stoppers, and synthetic closures (Nomacorc) were investigated. A comparison was made among closures left uncovered (controls), closures with the closure-glass interface covered, and closures completely covered with a polyurethane impermeable varnish. The oxygen ingress into the bottles was measured by a nondestructive colorimetric method. Technical cork stoppers were essentially impermeable to atmospheric oxygen during the first 24 months of storage. Oxygen within natural corks diffused slowly but continuously into the bottles over the first 12 months of storage and in very tiny amounts through the cork-glass interface the 12 months thereafter. Nomacorc synthetic closures were permeable to atmospheric oxygen, mainly after the first month of storage.     

Shoot‐produced,light‐dependent factors are partially involved in the expression of the arbuscular mycorrhizal (AM) status of AM host and non‐host plants

Arbuscular mycorrhizal (AM) colonization and hyphal attachment to the roots of a host plant, bean, and a non‐host plant, lupin, were compared when grown either with light or in the dark with the AM fungus Glomus mosseae. When grown with light, bean roots were heavily colonized whereas lupin roots showed no signs of colonization, no formation of appressoria and only scarce hyphal attachment to the roots. In contrast to roots of plants grown with light, to living roots of beans and lupins grown in the dark many hyphae were attached and appressoria were formed. The role of shoot produced, light‐dependent factors in the expression of the AM mycotrophic status of AM host and non‐host plants is discussed.<?show $6#>     

The effect of local anaesthesia on anaesthetic requirements for feline ovariectomy

A dose of supplementary ketamine was used to evaluate the anaesthetic sparing effect of adding local anaesthesia to general anaesthesia in cats undergoing ovariectomy. Fifty-six healthy cats were randomly assigned to receive lidocaine 2% (group L) as skin infiltration (1 mg kg(-1)), topical application (splash block) on both the ovaries (2 mg kg(-1), each) and on abdominal muscular layers (1 mg kg(-1)), or an equal volume of NaCl 0.9% at the same sites (group S). Anaesthesia was induced with a mixture of 20 microg kg(-1) medetomidine and 5 mg kg(-1) ketamine administered intramuscularly. Rectal temperature, ECG, heart rate and respiratory rate were measured continuously. Ketamine supplemental boli (1 mg kg(-1), intravenously) were administered in response to movements during surgery. Local lidocaine significantly reduced the need for supplementary ketamine. All animals were returned to their owners without complications. With this protocol, local anaesthetics reduced the need for injectable anaesthetic during feline ovariectomy.     

Farmers' knowledge and perceptions of termites as pests of yam (Dioscorea spp.) in Central Benin

Destruction of yam (Dioscorea spp.) tubers by termites is a major constraint to yam production in Central Benin. To obtain the basic information for the development of appropriate strategies of termites management in yam, a structured questionnaire was used to interview 142 farmers about their knowledge of termite species of yam, susceptibility of yam landraces, and management practices in 14 villages through the study area. A total of 45 vernaculars names of termites were recorded corresponding to 10 species. All the names given to termite species had a signification, mainly related to morphological aspects, type of damage, and termite caste. Eleven features were used by farmers to identify yam termites. The infestation of yam fields mostly occurred from October to April with Amitermes evuncifer and Trinevitermes oeconomus being the most damaging termite species. Overall, eight factors were identified by farmers as favouring the proliferation of termites in yam fields with drought being the most frequently reported factor. Farmers identified 11 yam landraces that were highly susceptible to termites attack, while 12 yam landraces were listed as resistant. Application of chemicals was the most commonly reported control method, followed by destruction of termite nest, and application of botanical extracts. According to farmers, the high multiplication rate of termites is the most important constraint in managing the issue of termites in yam.