Effects of temperature on survival and growth of juvenile spinefoot rabbitfish (Siganus rivulatus)

Interest in culturing marbled spinefoot rabbitfish Siganus rivulatus is increasing in countries on the Eastern Mediterranean, Red Sea and Arabian Gulf. However, information on environmental tolerances and requirements for optimal growth are scarce. In the present work, the temperature requirements for spinefoot rabbitfish were investigated in two experiments. In the first experiment, juvenile rabbitfish were distributed into eight 180 L square tanks at 12 fish per tank. The temperature in four tanks was reduced at a rate of 1 °C day^?1 and in four tanks was increased by 1 °C day^?1 until the fish stopped feeding. Minimum and maximum temperatures for feeding were recorded. In the second experiment, the fish were placed in four temperature treatments (17, 22, 27, 32 °C) at four replicates per treatment for 8 weeks. Survival and growth were evaluated. Fish stopped feeding at 14 and 36 °C. Their maximum growth rate was at 27 °C, and survival was 100% in all treatments. The relationship between specific growth rate and temperature was parabolic, described by the equation: SGR=?0.0014 (T³)+0.0798 (T²)?1.3089 (T)+6.7342. The results show that S. rivulatus is a eurythermal fish whose optimal temperature for growth is circa 27 °C.     

Broiler and layer poultry manures as nitrogen sources for ‘douglas’ strawberry in a tunnel production system

Floor litter from laying hens (1‐year old) and from broiler chickens (8‐week old) were incorporated into soil and compared with ammonium sulfate [(NH₄)₂SO₄] and an unfertilized control treatment as sources of nitrogen (N) for ‘Douglas’ strawberry grown in a tunnel production system. Layer litter had 5.6% moisture, 3.9% N and 1.7% P, while broiler litter had 7.7% moisture, 4.9% N and 1.6% P; they were applied at a rate of 12.8 and 10.8 t/ha on wet basis, respectively, in August 1991. Ammonium sulfate was applied at 100 kg N/ha in three split applications during the growing season. ‘Douglas’ strawberry plants were transplanted on 15 November 1991 and fruits were harvested from 1 April to 10 June 1992. Nitrate‐nitrogen (NO₃‐N) concentrations at last harvest were comparable in the soil and leaf tissue among all treatments (P>0.05); leaf NO₃‐N, early in the harvest period, was highest (P<0.05) in the broiler treatment (8.55%) and lowest in the control (5.15%). Yields were increased (P<0.05) by the manure, with the broiler treatment yielding the highest and the control yielding the least.     

Response of fall greenhouse COS lettuce to clear mulch and nitrogen fertilizer

Application of clear plastic mulch with or without N fertilizer did not significantly increase (P > 0.05) yield of cos lettuce (Lactuca sativa L. cv. Paris Island), grown in Fall in a greenhouse in the Mediterranean mountains. Yield ranged from 31 to 38 kg/50 heads. Leaf NO₃‐N and total P levels were higher in mulched than unmulched plants, and in fertilized than in unfertilized plants, and always above the sufficiency level in all treatments. Soil levels of NO₃‐N were higher under mulched than unmulched plots, and under fertilized than unfertilized plots, which had more than 50 ppm NO₃‐N at harvest. This indicates ample supply of N and thus explains the lack of response to added N. It may be concluded that in mild climates and on soils with adequate N, lettuce will not respond to the use of clear mulch and N fertilizer.     

The effect of thermal history on the maillard reaction in a glassy matrix

To test whether the extent of physical aging affected the reaction rate, Maillard reaction kinetics were studied in glassy model preservation systems subjected to two different thermal histories. The glass transition temperature and physical aging of the matrix were determined using differential scanning calorimetry, and the normalized heat capacities were modeled using the Tool-Narayanaswamy-Moynihan approach. Samples prepared using the different thermal histories initially had different degrees of aging, but these were practically indistinguishable after 10 h under the reaction conditions (65 degrees C); the samples underwent rapid structural relaxation at that temperature. The reaction of glucose and lysine in an amorphous trehalose/sucrose matrix was followed using spectrophotometric and chromatographic analysis. A difference in reaction rate could only be distinguished in the rate of consumption of glucose, which was approximately 20% faster in the minimally aged matrix; no significant differences were seen in any other indicator of reaction.     

Using restaurant food waste as feed for Nile tilapia production

More than 40% of human food produced is wasted and much of it in restaurants. Two 8‐week feeding experiments were performed to evaluate the suitability of using restaurant food waste to supplement commercial feed (CF) in the aquaculture of Nile tilapia Oreochromis niloticus. In the first experiment, five feeding regimens in which CF was substituted by waste‐based feed at 0, 25, 50, 75 and 100% of daily offering were evaluated. Results show that 25% of the CF can be replaced with waste‐based feed without any significant effect on survival, growth, feed conversion, hepatosomatic, viscerosomatic (VSI) indices, haemoglobin, haematocrit and total plasma protein (TPP). In the second experiment, seven feeding treatments were evaluated in which daily offerings of CF were alternated with waste‐based feed in 6‐day cycles. Results suggest that replacement between 25% and 33% is feasible without significantly affecting survival or growth. Again, no significant differences were observed in growth, feed conversion ratio, VSI, haemoglobin, haematocrit and TPP. Findings suggest that around 25% replacement of CF with Lebanese restaurant waste‐based feed can be utilized in the culture of O. niloticus thus improving financial returns of farmers while reducing the environmental impact of food waste.     

Morphological characterization of snake melon (<Emphasis Type="Italic">Cucumis melo</Emphasis> var. <Emphasis Type="Italic">flexuosus</Emphasis>) populations from Palestine

Genetic diversity in 50 snake melon accessions collected from Palestine (West Bank) was assessed by examining variation in 17 phenotypic characters. These accessions belonged to four important landraces of Cucumis melo var. flexuosus: Green “Baladi” (GB), white Baladi (WB), green Sahouri (GS), and white Sahouri (WS). Principal component analysis (PCA) and a dendrogram were performed to determine relationships among populations and to obtain information on the usefulness of those characters for the definition of cultivars. PCA revealed that secondary fruit skin color, flesh color, primary fruit skin color, and secondary skin color pattern were the principal characters to discriminate melon accessions examined in the present study. According to the scatter diagram and dendrogram, landraces of C. melo var. flexuosus: GB, WB, GS, and WS formed different clusters. However, based on Euclidean genetic coefficient distances, GB and WB had the least degree of relatedness with GS and WS, indicating distantly related landraces (Baladi and Sahouri). On the other hand, the highest degree of relatedness was detected between WS on one hand, and both GS and WB on the other indicating closely related cultivars. Fruit traits variability among the different snake melon landraces was evaluated and discussed in this study. This evaluation of fruit trait variability can assist geneticists and breeders to identify populations with desirable characteristics for inclusion in cultivars breeding programs.     

Acute and chronic effects of aqueous ammonia on marbled spinefoot rabbitfish,Siganus rivulatus (Forsskål 1775)

Ammonia is a metabolite of aquatic organisms which might reach deleterious levels in intensive fish farms. The aim of the present study was to determine median lethal concentrations (96‐h LC₅₀) of total ammonia nitrogen (TA‐N) on marbled spinefoot rabbitfish (Siganus rivulatus) and chronic effects of TA‐N on survival, growth and behaviour of juvenile rabbitfish over a 50 day period. In the first experiment, fish were exposed to 0, 2, 4, 6, 8, 10, 12, 14, 16, 18 and 20 mg L^?1 TA‐N for 96 h and survival evaluated. In the second experiment, 12 fish were stocked per 50‐L tank and treated with one of 0, 2, 4, 6, 8, 10 and 12 mg L^?1 TA‐N with three replicate tanks per treatment. Survival and growth were determined and histopathological alterations of gills due to chronic ammonia exposure were studied by light and electron microscopy. The 96‐h LC₅₀ values were 16–18 mg L^?1 TA‐N. In the chronic exposure experiment, fish reared in water with 0 mg L^?1 TA‐N had 100% survival and had 50% weight increase in 50 days. Fish at 2 and 4 mg L^?1 TA‐N all died whilst fish in 6, 8, 10 and 12 mg L^?1 TA‐N survived and grew albeit less than in treatment 0 mg L^?1. Gills from ammonia treated fish displayed severe histological and ultrastructural alterations including hyperplasia, hypertrophy and fusion of secondary lamellae, aneurysms and presence of pleomorphic altered cells. Chronic exposure to ammonia is deleterious to marbled spinefoot rabbitfish and low concentrations of ammonia appear to kill the fish in <50 days whilst fish can survive for more than 50 days at concentrations between 6 and 12 mg L^?1 TA‐N.     

Toxicity of Four Chemotherapeutic Agents to Rabbitfish Siganus rivulatus

As aquaculture evolves from extensive pond culture to intensive tank and cage systems, chemical dips and baths are increasingly being used to treat a concomitant increase in ectoparasitic and bacterial infestations. Some of the main disease‐causing agents are ectoparasites on the skin and gills of fish. Consequently, application of chemotherapeutics is increasing in aquaculture industries in order to control outbreaks of parasitic infestations. However, the toxic effect of commonly used chemotherapeutic agents on specific aquacultured fish species is often unknown. The present work was performed to test the effect of four commonly used chemical treatments on rabbitfish, Siganus rivulatus. The lethal concentrations for 50% of population (LC₅₀) of formalin, copper sulfate, potassium permanganate, and hydrogen peroxide for S. rivulatus juveniles treated for 1 h were assessed. Formalin and potassium permanganate tolerance values were determined by calculating 72‐h LC₅₀ values through probit analysis. The 72‐h LC₅₀ values for the formalin toxicity tests were 551.0 and 1.68 mg/L, respectively. LC₅₀ of copper sulfate and hydrogen peroxide could not be determined from the concentrations tested but were found to be >3 and >700 mg/L, respectively. Accordingly, treatment concentrations of formalin and potassium permanganate used for other fish species could be lethal to S. rivulatus, but the species appears to be quite tolerant to copper sulfate and hydrogen peroxide.     

Effect of Glass Transition and Cross‐Linking on Rheological Properties of Gluten: Development of a Preliminary State Diagram

The glass transition temperature of gluten at different moisture levels was determined by differential scanning calorimetry and mechanical spectrometry. The dynamic moduli (G′ and G″) of gluten with 10–40% moisture were measured as a function of temperature by pressure rheometry. At 10% moisture, gluten exhibited entangled polymer flow at 92–140°C and networking reactions at higher temperatures. At higher moisture levels, gluten experienced structured flow before networking cross‐linking reactions. The onset temperature of the reaction zone was 120°C in 20% moisture gluten and 93°C at moisture levels of 30–40%. Softening of the vitrified network occurred at 184, 181, and 170°C in 20, 30, and 40% moisture gluten, respectively. A preliminary state diagram of gluten as a function of moisture and temperature was developed.     

Chromosomal changes in uroepithelial carcinomas

This article reviews and summarizes chromosomal changes responsible for the initiation and progression of uroepithelial carcinomas. Characterization of these alterations may lead to a better understanding of the genetic mechanisms and open the door for molecular markers that can be used for better diagnosis and prognosis of the disease. Such information might even help in designing new therapeutic strategies geared towards prevention of tumor recurrences and more aggressive approach in progression-prone cases.The revision of 205 cases of uroepithelial carcinomas reported with abnormal karyotypes showed karyotypic profile characterized by nonrandom chromosomal aberrations varying from one or few changes in low-grade and early stage tumors to massively rearranged karyotypes in muscle invasive ones. In general, the karyotypic profile was dominated by losses of chromosomal material seen as loss of entire chromosome and/or deletions of genetic materials. Rearrangements of chromosome 9 resulting in loss of material from 9p, 9q, or of the entire chromosome were the most frequent cytogenetic alterations, seen in 45% of the cases. Whereas loss of material from chromosome arms 1p, 8p, and 11p, and gains of chromosome 7, and chromosome arm 1q, and 8q seem to be an early, but secondary, changes appearing in superficial and well differentiated tumors, the formation of an isochromosome for 5p and loss of material from 17p are associated with more aggressive tumor phenotypes. Upper urinary tract TCCs have identical karyotypic profile to that of bladder TCCs, indicating the same pathogenetic mechanisms are at work in both locales. Intratumor cytogenetic heterogeneity was not seen except in a few post-radiation uroepithelial carcinomas in which distinct karyotypic and clonal pattern were characterized by massive intratumor heterogeneity (cytogenetic polyclonality) with near-diploid clones and simple balanced and/or unbalanced translocations. In the vast majority of cases strong correlation between the tumors grade/stage and karyotypic complexity was seen, indicating that progressive accumulation of acquired genetic alterations is the driving force behind multistep bladder TCC carcinogenesis. Although most of these cytogenetic alterations have been identified for many years, the molecular consequences and relevant cancer genes of these alterations have not yet been identified. However, loss of TSG(s) from chromosome 9 seems to be the primary and important event(s) in uroepithelial carcinogenesis