Effect of Greenhouse Temperature on Tomato Yield and Ripening

High fuel costs have encouraged producers of greenhouse tomato (Solanum lycopersicum L.) in the mid-Atlantic region to reduce air temperatures during the day. However, effects on fruit ripening and yield are not known, especially under the low light conditions found in off-season production. This 2-yr study compared fruit ripening and yield of tomato under two temperature regimes during the fall season. Two sets of 18 tomato plants, three rows of six, were grown in soilless culture under either a warm or cool temperature regime. Temperatures were similar during night hours but allowed to rise to at least 21- 24 degrees C in the cool greenhouse section and 23-26 degrees C in the warm section, depending on daily solar heating. Mean 24 hour temperature difference between zones was less than 2 degrees C. Ripe tomato fruit were harvested and weighed 3 times per week for 8 weeks and the remaining un-ripened green tomatoes were weighed at the termination of the experiment to obtain total fruit biomass. The warm zone produced significantly greater weight of ripe tomatoes (23%) than the cool zone. However, total fruit weight (ripe and green), was not significantly different. Thus a relatively small increase in temperature (2 degrees C) during the mid-day was associated with a significant increase in fruit ripening but not in total fruit weight. This study showed that greenhouse temperature could be used to better manage fruit production to match weekly market demand without affecting total fruit weight and that consistently maintaining a cool greenhouse would delay tomato ripening and likely increase the potential for plant stress due to high fruit loads remaining on the vines

The Effects of Processing and Ripening on the Quality of Pizza Cheese

End of Project ReportThe main aims of this project were to quantify the changes in fuctionality during maturation of cheese and to develop an understanding of the factors which mediate the development of functionality. The approach to achieving these objectives involved the establishment of a suitable pilot plant production procedure for low moisture Mozzarella, developing and/or adapting existing methods for objective evaluation of the functional properties of pizza cheeses, and evaluating the effects of ripening and variations in cheesemaking conditions (e.g. pH at stretching) on the composition, yield and functionality of low moisture Mozzarella cheese. The main conclusions were as follows: The technology for developing low moisture Mozzarella cheeses, with different compositions and functionalities, via alteration of cheesemaking parameters, has been developed. A database has been established on the storage-related changes that occur in texture, proteolysis and functionality of low moisture Mozzarella cheeses of different compositions. In addition an extensive database on the compositional, biochemical, microstructural, rheological and/or functional properties of different commerical cheeses - low moisture Mozzarella, Cheddar and analogue pizza cheese, has been compiled. The functionality of low moisture Mozzarella changes markedly on storage/ripening at 4ºC. Initially, during the first 5-10 days of storage, the functionality of the baked cheese is poor but then improves on further storage as reflected by reductions in melt time and apparent viscosity (chewiness) and increases in stretchability and flowability. The changes in functionality are mediated by storage-related increases in pH, proteolysis, protein-bound water and free oil in the cheese. On prolonged storage (e.g. > 60 d at 4ºC), the cheese functionality becomes impaired as the shredded cheese develops an increased susceptibility to clumping/balling which makes it difficult to dispense the cheese onto the pizza pie and achieve a uniform surface distribution. Moreover, the baked cheese tends to exude excess free oil and loses its desired level of chewiness attaining a 'soupy' consistency. Novel methods were developed/adapted to objectively quantify functionality in the raw (susceptibility of shredded cheese to clump) and cooked (stretchability, chewiness, viscoelasticity) cheeses.Department of Agriculture, Food and the Marin

Biochemical and Functional Relationships in Cheese.

End of Project ReportCheese is used extensively in cooking applications, mainly because of its flavour and heat-induced functionality, which is a composite of different attributes such as softening, flow and stretch. The functional attributes of cooked cheese generally have a major impact on the quality of foods in which cheese is included as an ingredient, e.g. pizza pie. Owing to its importance in cookery applications, numerous studies have been undertaken on the effects of different factors on the age-related changes in the functionality of cooked cheese, especially Mozzarella, and to a lesser extent, Cheddar and processed cheese. These studies have shown that the functionality of natural cheese is dynamic, with the different functional attributes undergoing marked changes during ripening, and, for a given cheese variety, the desired functional attributes are optimum within a specific time frame during maturation. The time at which the cheese becomes functional and the width of the window - and hence the functional shelf-life, are affected by the extent of chemical changes, including the increase in proteolysis and the ratio of bound to free moisture. The main aims of this project were to investigate the effects of the following on the age-related changes in heat-related functional attributes (e.g. stretchability, fluidity) of cheese: * fat reduction, * the degree of fat emulsification, * the pH and calcium content and their interaction, * the correlation between proteolysis and functional attributes, especially attributes other than flowability, e.g. rheological properties of raw cheese, stretchability of heated cheese, and * the age-related changes in the functionality of cheeses other than Mozzarella, e.g. analogue pizza cheese and Emmental. At the outset of this project, comparatively little information was available on the effects of the above parameters on the age-related changes in heatinduced functional attributes (e.g. stretchability, fluidity) of cheese, especially for varieties other than Mozzarella.Department of Agriculture, Food and the Marin

Molecular clock-like evolution of human immunodeficiency virus type 1

AbstractThe molecular clock hypothesis states that the rate of nucleotide substitution per generation is constant across lineages. If generation times were equal across lineages, samples obtained at the same calendar time would have experienced the same number of generations since their common ancestor. However, if sequences are not derived from contemporaneous samples, differences in the number of generations may be misinterpreted as variation in substitution rates and hence may lead to false rejection of the molecular clock hypothesis. A recent study has called into doubt the validity of clock-like evolution for HIV-1, using molecular sequences derived from noncontemporaneous samples. However, after separating their within-individual data according to sampling time, we found that what appeared to be nonclock-like behavior could be attributed, in most cases, to noncontemporaneous sampling, with contributions also likely to derive from recombination. Natural selection alone did not appear to obscure the clock-like evolution of HIV-1

Hypoxia alters posterior cingulate cortex metabolism during a memory task: a 1H fMRS study

Environmental hypoxia (fraction of inspired oxygen (F(I)O(2)) ~ 0.120) is known to trigger a global increase in cerebral blood flow (CBF). However, regionally, a heterogeneous response is reported, particularly within the posterior cingulate cortex (PCC) where decreased CBF is found after two hours of hypoxic exposure. Furthermore, hypoxia reverses task-evoked BOLD signals within the PCC, and other regions of the default mode network, suggesting a reversal of neurovascular coupling. An alternative explanation is that the neural architecture supporting cognitive tasks is reorganised. Therefore, to confirm if this previous result is neural or vascular in origin, a measure of neural activity that is not haemodynamic-dependant is required. To achieve this, we utilised functional magnetic resonance spectroscopy to probe the glutamate response to memory recall in the PCC during normoxia (F(I)O(2) = 0.209) and after two hours of poikilocapnic hypoxia (F(I)O(2) = 0.120). We also acquired ASL-based measures of CBF to confirm previous findings of reduced CBF within the PCC in hypoxia. Consistent with previous findings, hypoxia induced a reduction in CBF within the PCC and other regions of the default mode network. Under normoxic conditions, memory recall was associated with an 8% increase in PCC glutamate compared to rest (P = 0.019); a change which was not observed during hypoxia. However, exploratory analysis of other neurometabolites showed that PCC glucose was reduced during hypoxia compared to normoxia both at rest (P = 0.039) and during the task (P = 0.046). We conclude that hypoxia alters the activity-induced increase in glutamate, which may reflect a reduction in oxidative metabolism within the PCC. The reduction in glucose in hypoxia reflects continued metabolism, presumably by non-oxidative means, without replacement of glucose due to reduced CBF

Identification of Burkholderia pseudomallei Near-Neighbor Species in the Northern Territory of Australia

Identification and characterization of near-neighbor species are critical to the development of robust molecular diagnostic tools for biothreat agents. One such agent, Burkholderia pseudomallei, a soil bacterium and the causative agent of melioidosis, is lacking in this area because of its genomic diversity and widespread geographic distribution. The Burkholderia genus contains over 60 species and occupies a large range of environments including soil, plants, rhizospheres, water, animals and humans. The identification of novel species in new locations necessitates the need to identify the true global distribution of Burkholderia species, especially the members that are closely related to B. pseudomallei. In our current study, we used the Burkholderia-specific recA sequencing assay to analyze environmental samples from the Darwin region in the Northern Territory of Australia where melioidosis is endemic. Burkholderia recA PCR negative samples were further characterized using 16s rRNA sequencing for species identification. Phylogenetic analysis demonstrated that over 70% of the bacterial isolates were identified as B. ubonensis indicating that this species is common in the soil where B. pseudomallei is endemic. Bayesian phylogenetic analysis reveals many novel branches within the B. cepacia complex, one novel B. oklahomensis-like species, and one novel branch containing one isolate that is distinct from all other samples on the phylogenetic tree. During the analysis with recA sequencing, we discovered 2 single nucleotide polymorphisms in the reverse priming region of B. oklahomensis. A degenerate primer was developed and is proposed for future use. We conclude that the recA sequencing technique is an effective tool to classify Burkholderia and identify soil organisms in a melioidosis endemic area

Application of Probiotic Bacteria to Functional Foods

End of Project ReportProbiotic cultures are described as live microbial feed supplements that improve intestinal microbial balance and are intended for maintenance of health or prevention, rather than the curing of disease. The demand for probiotic foods is increasing in Europe, Japan and the U.S. reflecting the heightened awareness among the public of the relationship between diet and health. Traditionally, the most popular food delivery systems for these cultures have been freshly fermented dairy foods, such as yogurts and fermented milks, as well as unfermented milks with cultures added. However, in the development of functional foods, the technological suitability of probiotic strains poses a serious challenge since their survival and viability may be adversely affected by processing conditions as well as by the product environment and storage conditions. This is a particular concern, given that high levels (at least 107 per gram or ml) of live micro-organisms are recommended for probiotic products. In previous studies (see DPRC No. 29) the successful manufacture of probiotic Cheddar cheese harbouring high levels (>108 cfu/g) of the probiotic Lactobacillus paracasei NFBC 338 strain was reported. Hence, the overall objective of these studies was to continue the development and evaluation of Functional Foods containing high levels of viable probiotic bacteria, with particular emphasis on overcoming the technological barriers and the identification of strains suited to particular applications, such as incorporation into Cheddar cheese and spray-dried powders.Department of Agriculture, Food and the Marin

Strongly aligned gas-phase molecules at Free-Electron Lasers

We demonstrate a novel experimental implementation to strongly align molecules at full repetition rates of free-electron lasers. We utilized the available in-house laser system at the coherent x-ray imaging beamline at the Linac Coherent Light Source. Chirped laser pulses, i. e., the direct output from the regenerative amplifier of the Ti:Sa chirped pulse amplification laser system, were used to strongly align 2,5-diiodothiophene molecules in a molecular beam. The alignment laser pulses had pulse energies of a few mJ and a pulse duration of 94 ps. A degree of alignment of \left = 0.85 was measured, limited by the intrinsic temperature of the molecular beam rather than by the available laser system. With the general availability of synchronized chirped-pulse-amplified near-infrared laser systems at short-wavelength laser facilities, our approach allows for the universal preparation of molecules tightly fixed in space for experiments with x-ray pulses.Comment: 10 pages, 5 figure