A novel aspartic acid protease gene from pineapple fruit (Ananas comosus): Cloning,characterization and relation to postharvest chilling stress resistance

A full-length cDNA encoding a putative aspartic acid protease (AcAP1) was isolated for the first time from the flesh of pineapple (Ananas comosus) fruit. The deduced sequence of AcAP1 showed all the common features of a typical plant aspartic protease phytepsin precursor. Analysis of AcAP1 gene expression under postharvest chilling treatment in two pineapple varieties differing in their resistance to blackheart development revealed opposite trends. The resistant variety showed an up-regulation of AcAP1 precursor gene expression whereas the susceptible showed a down-regulation in response to postharvest chilling treatment. The same trend was observed regarding specific AP enzyme activity in both varieties. Taken together our results support the involvement of AcAP1 in postharvest chilling stress resistance in pineapple fruits.     

Arsenic Resistance and Bioaccumulation of an Indigenous Bacterium Isolated from Aquifer Sediments of Datong Basin,Northern China

To obtain bacteria with arsenic accumulation potential that can be used to remove arsenic from contaminated waters, experiments were made to investigate the tolerance and accumulation to arsenic of an indigenous bacterium XZM002 isolated from aquifer sediments of Datong Basin, northern China. The results showed that strain XZM002 belongs to the genus Bacillus and has evolved defense mechanisms to reduce arsenic injury: the change of cellular shape from initial rod to oval and then to round with increment of arsenic toxicity. The effect of arsenate or arsenite on the bacterial growth was also investigated. Results showed that growth of the strain was inhibited under As(III) and high concentration As(V) (over 1200 μg l^?1) conditions in the first 2 days and promoted under low concentration As(V) (under 400 μg l^?1) condition. Its arsenic bioaccumulation potential was surveyed by monitoring the concentration changes of total arsenic and arsenic speciation in the medium and in the cytoplasm, and those of total arsenic on the membrane. Methylated arsenic species were not detected throughout the experiment. The results indicated that 11.5% of arsenic was removed from liquid medium into the bacterial cells and 9.22% of As(V) in the medium was transformed gradually to As(III) during 4 d of incubation. Approximately 80% of the total accumulated arsenic was adsorbed onto the membrane instead of into cytoplasm; and the arsenic accumulation almost approached saturation after incubation for 72 h.     

Costs and benefits of pre‐feeding for possum control

Abstract

Four control operations, each with paired pre‐feed and no‐pre‐feed treatments, and comprising two baited with carrot and two with cereal, provided strong support for the hypothesis that pre‐feeding produces higher possum kills than no pre‐feeding. In these replicates, even where high kills were achieved, the modelled two‐ to three‐fold extension of the period of population depression given by pre‐feeding was sufficient to warrant the expense of the additional bait sown. The benefits of pre‐feeding were clear‐cut, and were greatest where poorest kills were achieved, irrespective of bait type. Pre‐feeding is thus likely to reduce the probability of failure and should be considered a form of operational insurance.     

Variety,mulch and stage of inoculation effects on incidence of tomato spotted wilt virus disease in cucumber (Cucumis sativus L.)

Abstract

Tomato spotted wilt virus (TSWV) vectored by thrips is one of the major diseases affecting cucumber yield. Control of thrips is an underlying factor in its management. A study was conducted to determine the effect of time of inoculation, variety and mulch on disease incidence. Four varieties were inoculated with TSWV at cotyledon, 3 – 4 leaf and flower bud stages in a RCBD experiment replicated four times in a greenhouse. In the field, a 2×8 factorial design where two cucumber varieties were raised on seven types of mulches (red, yellow, silver, clear, black, white, and straw) with unmulched plots as controls was used. Variety Marketer was more tolerant to the disease compared to other varieties. Most varieties were generally tolerant to TSWV at cotyledonous but susceptible at 3 – 4 leaf and flower bud stages. Silver and clear mulches significantly suppressed thrip populations, yield and quality under field conditions.     

Optimal policies of non-cross-resistant chemotherapy on Goldie and Coldman’s cancer model

Mathematical models can be used to study the chemotherapy on tumor cells. Especially, in 1979, Goldie and Coldman proposed the first mathematical model to relate the drug sensitivity of tumors to their mutation rates. Many scientists have since referred to this pioneering work because of its simplicity and elegance. Its original idea has also been extended and further investigated in massive follow-up studies of cancer modeling and optimal treatment.     

Chronotherapy in Coronary Heart Disease: Comparison of Two Nitrate Treatments

The purpose of this study was to assess the ischemic burden and the hemodynamic changes during daily activities in patients with coronary heart disease. Three exercise tests were performed during the day (10:00 a.m., 2:00 p.m., 6:00 p.m.), recording ST-segment depression, pulmonary artery pressure, pulmonary wedge pressure, and cardiac output as well as heart rate and systemic blood pressure during placebo and nitrate therapy. With placebo as well as nitrate therapy there was a gradual increase of ischemia and preload and a decrease of cardiac output during the day. High nitrate concentrations led to a significant reduction of both preload and ST depression with a marked circadian phase dependency of cardiovascular effects.     

Assessing the efficacy of spray-delivered ‘eco-friendly’ chemicals for the control and eradication of marine fouling pests

Despite its frequent use in terrestrial and freshwater systems, there is a lack of published experimental research examining the effectiveness of spray-delivered chemicals for the management of non-indigenous and/or unwanted pests in marine habitats. This study tested the efficacy of spraying acetic acid, hydrated lime and sodium hypochlorite for the control of marine fouling assemblages. The chemicals are considered relatively ‘eco-friendly’ due to their low toxicity and reduced environmental persistence compared to synthetic biocides, and they were effective in controlling a wide range of organisms. Pilot trials highlighted acetic acid as the most effective chemical at removing fouling cover, therefore it was selected for more comprehensive full-scale trials. A single spray of 5% acetic acid with an exposure time of 1 min effectively removed up to 55% of the invertebrate species present and 65% of the cover on fouled experimental plates, while one application of 10% acetic acid over 30 min removed up to 78% of species present and 95% of cover. Single-spray treatments of 5% acetic acid reduced cover of the tunicate pest species Didemnum vexillum by up to 100% depending on the exposure duration, while repeat-spraying ensured that even short exposure times (1 min) achieved ～99% mortality. Both 5 and 10% acetic acid solutions appeared equally effective at removing the majority of algal species. This technique could be used for controlling the introduction of unwanted species or preventing the spread of pests, and is applicable to use on a variety of natural and artificial substrata, or for the treatment of structures that can be removed from the water.     

Timing Light Treatment for Eastward and Westward Travel Preparation

Jet lag degrades performance and operational readiness of recently deployed military personnel and other travelers. The objective of the studies reported here was to determine, using a narrow bandwidth light tower (500 nm), the optimum timing of light treatment to hasten adaptive circadian phase advance and delay. Three counterbalanced treatment order, repeated measures studies were conducted to compare melatonin suppression and phase shift across multiple light treatment timings. In Experiment 1, 14 normal healthy volunteers (8 men/6 women) aged 34.9±8.2 yrs (mean±SD) underwent light treatment at the following times: A) 06:00 to 07:00 h, B) 05:30 to 07:30 h, and C) 09:00 to 10:00 h (active control). In Experiment 2, 13 normal healthy subjects (7 men/6 women) aged 35.6±6.9 yrs, underwent light treatment at each of the following times: A) 06:00 to 07:00 h, B) 07:00 to 08:00 h, C) 08:00 to 09:00 h, and a no-light control session (D) from 07:00 to 08:00 h. In Experiment 3, 10 normal healthy subjects (6 men/4 women) aged 37.0±7.7 yrs underwent light treatment at the following times: A) 02:00 to 03:00 h, B) 02:30 to 03:30 h, and C) 03:00 to 04:00 h, with a no-light control (D) from 02:30 to 03:30 h. Dim light melatonin onset (DLMO) was established by two methods: when salivary melatonin levels exceeded a 1.0 pg/ml threshold, and when salivary melatonin levels exceeded three times the 0.9 pg/ml sensitivity of the radioimmunoasssy. Using the 1.0 pg/ml DLMO, significant phase advances were found in Experiment 1 for conditions A (p?<?.028) and B (p?<?0.004). Experiment 2 showed significant phase advances in conditions A (p?<?0.018) and B (p?<?0.003) but not C (p?<?0.23), relative to condition D. In Experiment 3, only condition B (p?<?0.035) provided a significant phase delay relative to condition D. Similar but generally smaller phase shifts were found with the 2.7 pg/ml DLMO method. This threshold was used to analyze phase shifts against circadian time of the start of light treatment for all three experiments. The best fit curve applied to these data (R²?=?0.94) provided a partial phase-response curve with maximum advance at approximately 9–11 h and maximum delay at approximately 5–6 h following DLMO. These data suggest largest phase advances will result when light treatment is started between 06:00 and 08:00 h, and greatest phase delays will result from light treatment started between 02:00 to 03:00 h in entrained subjects with a regular sleep wake cycle (23:00 to 07:00 h).     

Effects of different thermal treatments during embryonic development on the artificial incubation efficiency of crayfish (Austropotamobius pallipes Lereboullet) eggs. Control of the embryogenetic duration and implications for commercial production

Summary

The development and improvement of artificial incubation techniques for freshwater crayfish eggs and their incorporation into the working schedule of breeding centres is of great interest for commercial production. Factors such as the water circulation system, flow rate, thermal treatment, etc., could strongly influence the success of the process. The present study attempts to test the possible influence of one of these variables, the thermal regime, on both the duration of embryonic development and the efficiency rates obtained in the artificial incubation of white-clawed crayfish (Austropotamobius pallipes) eggs. Four different thermal treatments were tested (three of them included a period at low temperature: 4°-5°C). Survival rates to juvenile stage 2 were similar in the four cases, ranging between 66.7 and 72.7%. We conclude that water cooling (an expensive management procedure) is not necessary in astacid breeding centres provided that egg development takes place at moderately low temperatures (8°-10°C) with a subsequent increase of up to 15°C from the eyed stage. However, the inclusion of periods at low temperature (4°-5°C) allows the staggered production of juvenile batches throughout a 3-week period without adverse effects on efficiency rates. This could be useful to breeding centres in meeting seasonal market requirements. In our study, egg and juvenile losses (mortality rate: 15–20%) were concentrated during the last phases of embryogenesis, particularly from the eyed stage to juvenile stage 2, during which they amounted to more than 90% of the overall mortality which took place during the artificial incubation process.