Fed-batch culture of Candida guilliermondii FTI 20037 for xylitol production from sugar cane bagasse hydrolysate

A fed-batch culture system was used to study xylitol production by Candida guilliermondii FTI 20037 in a synthetic and a sugar cane bagasse hydrolysate medium. The values achieved for xylitol yield and volumetric productivity were, respectively, 0 · 84 g g⁻¹ and 0 · 64 g l⁻¹ h⁻¹ using the synthetic medium and 0 · 78 g g⁻¹ and 0 · 62 g l⁻¹ h⁻¹ using the hydrolysate medium.     

Survey of wound-induced ethylene production by excised root segments

Ethylene production was measured from excised 10-mm apical and subapical root segments from 50 cultivars in 19 species of 7 families. Monocotyledonous species tended to have much lower rates of ethylene production than dicotyledonous species. Ethylene production was generally higher in apical root segments than in subapical segments within 1 h of wounding. However, cultivars of Cucumis melo , C. sativus , Helianthus annuus , Hibiscus esculentus , and Zea mays had higher rates of ethylene production from subapical segments. In apical root segments, Phaseolus aureus cv. Berken had the highest ethylene production rate (76.7 ηl g⁻¹ h⁻¹), while Zea mays cv. Silver Queen had the lowest rate (0.6 ηl g⁻¹ h⁻¹). In subapical root segments, Cucumis sativus cv. Armenian had the highest rate (55.7 ηl g⁻¹ h⁻¹), while Zea mays cv. Silver Queen again had the lowest rate (0.6 ηl g⁻¹ h⁻¹). The many different responses in magnitude and kinetics of wound-induced ethylene production among the species, cultivars and tissues should provide interesting and useful systems with which to study wound responses and induced ethylene production.     

Relationships between bone growth rate, body mass and resting metabolic rate in growing amniotes: a phylogenetic approach

We explored the factors that explain the variation in resting metabolic rates (RMR) in growing amniotes by using the phylogenetic comparative method. For this, we measured raw RMR (mL O₂ h⁻¹), body mass, body mass growth rate, and periosteal bone growth rate in a sample of 44 growing individuals belonging to 13 species of amniotes. We performed variation partitioning analyses, which showed that phylogeny explains a significant fraction of the variation of mass-specific RMR (mL O₂ h⁻¹ g⁻¹), and that the cost of growth is much higher than the cost of maintenance. Moreover, we tested the hypothesis of the independence of energy allocation, and found that maintenance metabolism and growth rates are not significantly related. Finally, we calculated the statistical parameters of the relationship between geometry-corrected RMR (mL O₂ h⁻¹ g^−0.67) and bone growth rate. This relationship could potentially be used in palaeobiology to infer RMR from bone tissue samples of fossil species by assuming Amprino's rule (according to which bone tissue types reflect bone growth rates). These estimates would be especially interesting for Mesozoic non-avian theropod dinosaurs and Permian and Triassic therapsids to investigate, respectively, the origin of avian and mammalian endothermy.  © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 92 , 63–76.     

Energy density of anchovy Engraulis encrasicolus L. in the Adriatic Sea

European anchovy Engraulis encrasicolus , with total lengths ranging from 40·0 to 132·5 mm, were sampled during October 2002 and May 2003 in the northern Adriatic Sea in order to estimate their energy densities ( E _D). A highly significant ( P  < 0·001) relationship between E _D(y)(J g⁻¹wet mass) and per cent dry mass ( x ) was found: y  = 321 x  − 3316·9 ( n  = 161, r ² = 0·82).     

Thermogenesis of three species of Arum from Crete

Inflorescences of arum lilies have a three-part spadix with a scent-producing, sterile appendix above two bands of fertile male and female florets. The appendix and male florets are thermogenic, but with different temporal patterns. Heat-production was measured in Arum concinnatum , A. creticum and A. idaeum . The male florets of A. concinnatum showed a 3 d continuous episode of thermogenesis with three waves, and the appendix warmed in a single, 6 h episode. Maximum fresh-mass-specific CO₂ production rate was 0.17  µ mol s⁻¹ g⁻¹ to achieve a 10.9 °C temperature elevation by the appendix, and 0.92  µ mol s⁻¹ g⁻¹ to achieve a 4.8 °C elevation by male florets. Reversible, physiological temperature regulation was not evident in either tissue. Respiration increased with tissue temperatures with Q₁₀ values of 1.8–3.9, rather than less than 1.0 as occurs in thermoregulatory flowers. Experimental step changes in temperature of appendix and male floret tissues also failed to show thermoregulatory responses. The patterns of thermogenesis therefore appear to be fixed by the temporal sequence of blooming. Thermogenesis in the alpine species, A. creticum and A. idaeum , was significantly lower than in the lowland A. concinnatum , possibly related to difficulty in raising floral temperature in their cold and windy habitat.     

Impact of temperature on food intake and growth in juvenile burbot

The effect of temperature on food consumption, food conversion and somatic growth was investigated with juvenile burbot Lota lota (age 0 years). Juvenile burbot showed a significant dome shaped relationship between relative daily food consumption ( C _R) and temperature ( T ) with C _R = − 0·00044 T ² + 0·01583 T  − 0·06010; ( n  = 90, r ² = 0·61). Maximum C _R was at 17·9° C (95% CL 17·2–18·6° C). The temperature related instantaneous growth rate ( G ) also followed a dome shaped function with G  = − 0·000063 T ² + 0·002010 T  − 0·007462; ( n  = 95, r ² = 0·57), with maximum growth rate at 16·0° C (95% CL 15·3–16·6° C). A significant linear relationship was found between the water temperature and the conversion coefficient ( C _C) with C _C = − 1·63 T  + 59·04; ( n  = 80, r ² = 0·74). The results indicate that juvenile burbot in large lakes benefit from higher water temperatures in the littoral zone, by increased food uptake and growth, especially during the warm summer months. Because profundal water temperatures do not reflect the optimal temperature for food consumption in large burbot, temperature is unlikely to be the main proximate factor for the obligate littoral‐profundal migration of juvenile burbot observed in many lake populations.     

Ecosystem productivity can be predicted from potential relative growth rate and species abundance

We show that ecosystem-specific aboveground net primary productivity (SANPP, g g⁻¹ day⁻¹, productivity on a per gram basis) can be predicted from species-level measures of potential relative growth rate (RGR_max), but only if RGR_max is weighted according to the species' relative abundance. This is in agreement with Grime's mass-ratio hypothesis. Productivity was measured in 12 sites in a French Mediterranean post-agricultural succession, while RGR_max was measured on 26 of the most abundant species from this successional sere, grown hydroponically. RGR_max was only weakly correlated ( r ² = 0.12, P  < 0.05) with field age when species abundance was not considered, but the two variables were strongly correlated ( r ² = 0.81, P  < 0.001) when the relative abundance of species in each field was taken into account. SANPP also decreased significantly with field age. This resulted in a tight relationship ( r ² = 0.77, P  < 0.001) between productivity and RGR_max weighted according to species relative biomass contribution. Our study shows that scaling-up from the potential properties of individual species is possible, and that information on potential and realized species traits can be integrated to predict ecosystem functioning.     

Utilization of several plant proteins by gibel carp (Carassius auratus gibelio)

Six isonitrogenous (gross protein content 35%) and isoenergetic (gross energy content 17 kJ g⁻¹) diets were formulated to investigate the effects of inclusion of plant proteins on the gibel carp ( Carassius auratus gibelio L.). The plant proteins tested were: soybean cake (SBC), potato protein concentrate (PPC), peanut cake (PNC), cottonseed cake (CSC) and rapeseed cake (RSC). Fish meal (FM) was used as control. In each diet, 27% of the protein was supplied by fish meal, and the rest supplied by the plant protein tested. Each diet was fed to three groups of gibel carp for 8 weeks in a recirculation system. Specific growth rate (SGR) in fish fed the control diet was significantly higher than those in the other groups, and SGR in fish fed the PPC was significantly lower than in fish fed other plant proteins. There was no significant difference in SGR among the other groups. Feeding rates were ranked in the order: RSC > CSC > FM > PNC > SBC > PPC. Conversion efficiency was highest in groups fed FM, SBC and PNC, followed by groups fed CSC and RSC, and was lowest in the group fed PPC. The fish fed PPC showed lower protein retention than those fed FM and SBC. FM showed highest energy retention while PPC showed lowest. There was no significant relationship between SGR and intake of digestible protein (g g⁻¹ day⁻¹), digestible lysine (g g⁻¹ day⁻¹), digestible methionine (g g⁻¹ day⁻¹) or digestible total essential amino acids (g g⁻¹ day⁻¹), suggesting that the differences in SGR could not alone account for any of these variables.     

Effect of feeding level and feeding frequency on specific dynamic action in Silurus meridionalis

The effect of feeding level ( F _L; 0·5 to 4% dry diet mass per wet fish body mass) and feeding frequency (once every 4 days to twice per day) on postprandial metabolic response was investigated in southern catfish Silurus meridionalis at 27·5° C. The results showed that there was no significant difference in the specific dynamic action (SDA) coefficient among the groups of different feeding levels ( P  > 0·05). The duration increased from 26·0 to 40·0 h and the peak metabolic rate increased from 207·8 to 378·8 mg O₂ kg⁻¹ h⁻¹ when the feeding level was increased from 0·5 to 4%. The relationship between the peak metabolic rate ( R _P, mg O₂ kg⁻¹ h⁻¹) and F _L could be described as: R _P = 175·4 + 47·3 F _L( r ² = 0·943, n  = 40, P  < 0·001). The relationship between the SDA duration ( D , h) and F _L could be described as D =30·97 F _L^0·248 ( r ²=0·729, n =40, P  < 0·001).     

The use of a surface adhesion immunofluorescent (SAIF) method for the rapid detection of Yersinia enterocolitica serotype O:3 in meat

This study examined the attachment kinetics of Yersinia enterocolitica serotype O:3 to determine the optimum conditions for its isolation from meat enrichment systems using a novel surface adhesion technique. Minced beef was inoculated with Y. enterocolitica at an initial level of 10 cfu g⁻¹ and incubated at 25 °C in an enrichment broth. Yersinia was recovered from enriched samples on polycarbonate membranes by surface adhesion and enumerated using immunofluorescence microscopy. The surface adhesion immunofluorescence technique (SAIF) had a minimum detection limit of approximately 4·0–4·5 log₁₀ cfu ml⁻¹ and provided good correlation between the estimation of the numbers of Yersinia in the enrichment broth derived from plate counts on Yersinia Selective agar (CIN) and those determined by SAIF ( r ² ₌ 0·94; rsd ₌ ± 0·21). A derived regression equation of the SAIF count vs plate counts was used to predict Y. enterocolitica numbers in spiked meat samples stored at 0 °C for up to 20 d. The numbers as predicted by the SAIF method showed good correlation with counts derived by plating techniques ( r ² ₌ 0·78; rsd ₌ ± 0·42). The application of the SAIF technique for the rapid detection of Y. enterocolitica serotype O:3 from meat is discussed.     

Identification of the causative agent of cutaneous leishmaniasis in Chichaoua province, Morocco

Cutaneous leishmaniasis (CL) in Morocco is caused by three species, Leishmania major, L. tropica and L. infantum. CL has been known in Chichaoua province since 2000. Using DNA extracted from microscopic slides and parasite cultures, collected in the years 2006 and 2009, we identified for the first time L. tropica as the causative agent of CL in this region. Species identification was achieved by performing the ITS1-PCR-RFLP approach. By using this method it was possible to identify parasites in Giemsa stained slides containing less than five parasites per oil-immersion field even they were conserved for up to four months.     

Is white muscle anaerobic glycolysis capacity indicative of competitive ability in Arctic charr?

Food ingestion to assess dominance status, indicated that dominant Arctic charr Salvelinus alpinus displayed significantly higher white muscle pyruvate kinase (PK) and lactate dehydrogenase (LDH) activities compared to subordinate fish [PK = 429·57 ± 76·37 v . 331·00 ± 61·73 U g⁻¹ tissue ( P  = 0·022) and LDH = 929·33 ± 61·03 v . 775·25 ± 110·96 U g⁻¹ tissue; ( P  = 0·0007)].     

Influence of egg vitamin A status and egg incubation temperature on subsequent development of the early vertebral column in Atlantic salmon fry

The effect of egg vitamin A (VA) status and egg incubation temperature on the development of spinal disorders was investigated in Atlantic salmon Salmo salar fry. Atlantic salmon eggs were sorted into two groups with high VA (3·3 ± 0·1 μg retinol g⁻¹ dry mass) and low VA (2·2 ± 0·3 μg retinol g⁻¹ dry mass) status before fertilization and incubated at high (14° C) or low (8° C) temperature from 133 day degrees until the onset of feeding. High egg incubation temperatures increased the concentration of retinol in the eggs: the high VA and high temperature group displayed a significantly higher retinol concentration than the high VA and low temperature group ( P  = 0·001). After hatching, all experimental groups increased their retinol concentration. The source of the increased retinol levels was probably retinal, although astaxanthin may also be a VA precursor after hatching. Atlantic salmon fry incubated at high temperatures had increased amounts of notochord tissue. When measuring morphogenic activity in the notochord using the expression of sonic hedgehog ( shh , mRNA), however, no significant difference was found between the experimental groups. No clear effect of VA status or incubation temperature could be found on the formation of the early vertebral column although Atlantic salmon fry incubated at low temperatures had less regular constrictions of the prospective vertebral column than fry incubated at high temperatures.     

Culture-independent analysis of desulfovibrios in the human distal colon of healthy, colorectal cancer and polypectomized individuals

The production of hydrogen sulphide, an end product of metabolism by the sulphate-reducing bacteria (SRB) has been cited as a potential aetiological agent in gastrointestinal disease. Quantitative PCR (Q-PCR) assays to enumerate desulfovibrios from two gastrointestinal disease groups: colorectal cancer (CRC) n =27 and polypectomized individuals (PP) n =27, and two healthy control groups, elderly (H1) n =8 and young adults (H2) n =30 was performed. Analysis of Desulfovibrio sp. diversity using the dissimilarity sulphite reductase ( dsrAB ) gene as a molecular marker was also undertaken. Q-PCR detected Desulfovibrio sp. in all samples and no significant difference was observed for PP, H1, H2 with gene copy numbers of Desulfovibrio sp. averaging at 10⁶ g⁻¹ of faeces. Significantly reduced numbers of Desulfovibrio sp. were observed for CRC (10⁵ g⁻¹) compared with both PP and H2 groups ( P <0.05). Diversity analysis indicated that a low Desulfovibrio sp. diversity and the predominance of Desulfovibrio piger was a feature of both healthy and disease groups. In addition, a dsrAB gene sequence distantly related to a Gram-positive SRB was also recovered, highlighting the importance of cultivation-independent techniques for furthering our understanding of the diversity of the human gastrointestinal ecosystem.     

Phenolic compounds in peach (Prunus persica) cultivars at harvest and during fruit maturation

Six peach and six nectarine cultivars were evaluated for the phenolic content in their pulp and peel tissues. Chlorogenic acid, catechin, epicatechin, rutin and cyanidin-3-glucoside were detected as the main phenolic compounds of ripened fruits. The concentration was always higher in peel tissue, with average values ranging from 1 to 8 mg g⁻¹ dry weight (DW) depending on cultivar. Of the tested varieties, the white-flesh nectarine 'Silver Rome' emerged as the cultivar with the highest amount of total phenolics. Phenolic compounds were also profiled during fruit growth and ripening in the yellow nectarine cv. 'Stark Red Gold', which showed a decreasing concentration during fruit development in both peel and pulp tissues. Average amounts of total phenolics were approximately 25 mg g⁻¹ DW 60 days after full bloom and decreased to 3 mg g⁻¹ DW at ripening in pulp tissue. Differences among peel and pulp composition show the different dietetic and antioxidant potential of fruits consumed unpeeled and peeled.     

Persistence of Shiga toxin-producing Escherichia coli O26 in various manure-amended soil types

Aims:  To evaluate the behaviour of Shiga toxin-producing Escherichia coli (STEC) O26 strains inoculated in manure-amended soils under in vitro conditions.
Methods and Results:  Four green fluorescent protein (GFP)-labelled STEC O26 strains were inoculated in duplicate (at 10⁶ CFU g⁻¹) in three different manure-amended soil types, including two loam soils (A and B) and one clay loam soil (C), and two incubation temperatures (4 and 20°C) were tested. STEC counts and soil physical parameters were periodically monitored. STEC O26 cells were able to persist during extended periods in soil even in the presence of low moisture levels, i.e. less than 0·08 g H₂O g⁻¹ dry soil. At 4 and 20°C, STEC could be detected in soil A for 288 and 196 days, respectively, and in soils B and C for at least 365 days postinoculation at both temperatures. The ambient temperature (i.e. 20°C) was significantly associated with the highest STEC count decline in all soils tested.
Conclusions:  The temperature and soil properties appear to be contributory factors affecting the long-term survival of STEC O26 in manure-amended soils.
Significance and Impact of the Study:  This study provides useful information regarding the ecology of STEC O26 in manure-amended soils and may have implications for land and waste management.     

The effect of an emergent macrophyte (Typha angustifolia) on sediment resuspension in a shallow north temperate lake

1. The effects of emergent macrophytes on water turbidity and sediment resuspension in the shallow Kirkkojärvi basin of Lake Hiidenvesi were studied with sediment traps, and concomitant sediment and water samples. The study was conducted during May–August in three different zones of a stand of the emergent Typha angustifolia .
2. Within the stand (5 m from the edge), both the concentration of suspended solids and the rate of sediment resuspension were significantly lower than at the edge and outside the stand (5 m from the edge). The differences between the zones increased towards the end of summer together with the growing stem density. During the study period (82 days), 2210 g dw m⁻² of sediment was resuspended in the outer zone. At the edge and in the inner zone, the corresponding numbers were 1414 and 858 g dw m⁻², respectively.
3. With the resuspended sediment, 39.4 mg P  m⁻² day⁻¹ was brought to the water column outside the stand, 22.4 mg P  m⁻² day⁻¹ at the edge and 13.4 mg P  m⁻² day⁻¹ within the stand.
4. In early summer, the concentration of suspended solids had a highly significant positive effect on soluble reactive phosphorus (SRP) concentration in the water, whereas in late summer no effect was found. During the study period, phosphorus retention by emergent macrophyte stands corresponded to 3–5% of the present annual external phosphorus loading of the Kirkkojärvi basin.     

Identification of Leishmania spp. by Radiorespirometry

SYNOPSIS Preliminary investigation of the application of radiorespirometric technic to protozoan parasites of man indicates a potential for rapid identification. This technic, developed for identification of bacteria, was modified for use with culture forms of Leishmania. Five strains of Leishmania were compared: 2 of L. donovani , 2S and K; L. brasiliensis , 2936 and B; and 1 of L. tropica , A. Consistent and rapid (2 hr) identification was obtained by the radiorespirometric procedure. A computer-type analysis of the radiorespirometric profiles of the 5 strains permitted correct identification of each isolate at the strain level 100% of the time. This technic offers several advantages over many current procedures for identification of protozoan parasites: (A) It is simple, rapid and highly reproducible. (B) Since it does not rely on visual or spectrophoto-metric determination, it may be conducted in the presence of optically complex substances. (C) It requires relatively low numbers of organisms (2 × 10⁵/¹⁴C-labeled substrate). (D) It is based on differential enzymic activity between species and strains of organisms and therefore, ultimately, on inherent genetic determinates of the parasites. (E) Further development of the procedure and accumulation of a data reference "bank" would allow automation of most of the identification process.     

Impairment of the human phagocyte oxidative responses caused by Leishmania lipophosphoglycan (LPG): In vitro studies

Abstract Lipophosphoglycan (LPG), a surface glycoconjugate of Leishmania promastigotes, has been reported as playing an active role in protecting the parasite within phagolysosomes, by an impairment of monocyte oxidative responses. In this study the effect of LPG on the oxidative burst of human peripheral monocytes, eosinophils and neutrophils was evaluated. Our results demonstrated that either superoxide anion (O₂⁻) or hydrogen peroxide (H₂O₂) release by LPG-pretreated cells was diminished, emphasizing the ability of this glycoconjugate to impair the oxidative activity of all phagocytes.     

Ethylene synthesis and growth in embryogenic tissue of Norway spruce: Effects of oxygen, 1-aminocyclopropane-1-carboxylic acid, benzyladenine and 2,4-dichlorophenoxyacetic acid

Ethylene production from an embryogenic culture of Norway spruce ( Picea abies L.) was generally low. ca 2.5 nl g⁻¹ h⁻¹, whereas 1-aminocyclopropane-1 -carboxylic acid (ACC) concentration was high, fluctuating between 50 and 500 nmol g⁻¹ during the 11-day incubation period. Hypoxia (2.5 and 5 kPa O₂) rapidly inhibited ethylene production without subsequent accumulation of ACC. Exogenous ACC (1, 10 and 100 μ M ) did not increase ethylene production, but the highest concentrations inhibited tissue growth. Ethylene (7 μl I⁻¹) did not inhibit growth either when supplied as ethephon in the medium or in a continuous flow system. Benzyladenine (BA) had little effect on ethylene production, although it was necessary for sustaining the ACC level. Omission of 2.4-dichloro-phenoxyacetic acid (2.4-D) from the medium caused ethylene production to increase from about 2.5 to 7 nl g⁻¹ h⁻¹ within the 11-day incubation period. Although 2.4-D did not specifically alter the endogenous level of ACC, the lowest ACC level, 33 nmol g⁻¹, was observed in tissue treated with 2.4-D (22.5 μ M ) and no BA for 11 days. Data from this treatment were used to estimate the kinetic constants for ACC oxidase, the apparent K_m was 50 μ M and V_max 2.7 nl g⁻¹ h⁻¹. Growth of the tissue was strongly inhibited by 2.4-D in the absence of BA, but weakly in the presence of BA (4.4 μ M ). The results suggest that ethylene or ACC may be involved in the induction of embryogenic tissue and in the early stages of embryo maturation.