Specific dynamic action (SDA) in the supralittoral isopod,Ligia pallasii: Identification of components of apparent SDA and effects of dietary amino acid quality and content on SDA

• 1.1. Specific Dynamic Action (SDA) effects of diet were investigated in the supralittoral isopod, Ligia pallasii, using defined chemical diets.
• 2.2. “Apparent SDA”, or the total rise in metabolic rate following a meal, was resolved in animals eating a nutritionally complete chemical diet into three components: 8% mechanical costs of moving food through the gut, 40% “excitement costs” due to investigator disturbance and presence of food, and 52% SDA.
• 3.3. Excitement costs in animals exposed to food but which chose not to eat showed non-significant variation between diets containing different levels of chemical nutrients, but were significantly less on a diet containing only cellulose and agar.
• 4.4. SDA increased with increasing concentration of amino acids in the diet.
• 5.5. Substitution of whole-protein casein for free amino acids in the diet had no significant SDA effect, while substitution of free amino acids in the ratio found in casein more than doubled the SDA effect.
• 6.6. Deletion of alanine from the diet caused no significant effect on SDA, while deletion of phenylalanine caused a highly significant elevation in SDA.

     

四川大头茶气候生态类型的多元分析及SDA判别分析

应用数量分类（ＣＡ） 和排序（ＰＣＡ、ＣＯＡ） 方法分析了四川大头茶７ 个地理种群２３ 个性状特征,并用判别分析（ＳＤＡ） 检验分类排序的正确性．结果表明,四川大头茶不同地理种群可划为３ 个气候生态类型：云南文山型即Ⅰ型、广西型即Ⅱ型、四川型即Ⅲ型;同时据其判别分析之判别轴图可知,没有位点被错划．通过比较地理气候因子对各类型的贡献率,得知光照对３ 类生态类型的形成分化起主导作用     

Specific dynamic action (SDA) in the supralittoral isopod,Ligia pallasii: Relationship of growth to SDA

• 1.1. The relationship of Specific Dynamic Action (SDA) to growth was examined in the supralittoral isopod Ligia pallasii using a seaweed diet fed at different rations.
• 2.2. Animals increased in live weight by 33% on an ad libitum or 100% diet and by 2% on a 20% ration over a 10-week period.
• 3.3. Weight-specific VO₂ was significantly higher in animals eating the 100% diet than in ones eating the 20% diet. Decline in VO₂ with time in animals on the 20% diet was probably due to poor health associated with a maintenance ration.
• 4.4. SDA per unit weight of food eaten was 18% higher in the 20% diet group than in the 100% one, and values remained constant over time in both groups.
• 5.5. k₁ growth efficiencies (production/consumption) were higher in animals on 100% ration than in ones on 20% ration. Efficiencies declined with time in both diet-groups and fell below zero in the 20% ration-group, coincidental with weight-loss in some of the animals.
• 6.6. Overall SDAs for the 10-week period were positively correlated with growth (r₂ = 0.77), but there was no way to separate this from amounts eaten as an effect on SDA.

     

Specific dynamic action (SDA) in the supralittoral isopod,Ligia pallasii: Effect of ration and body size on SDA

• 1.1. Ration and body size effects on specific dynamic action (SDA) were investigated in the supralittoral isopod Ligia pallasii using seaweed and chemical diets.
• 2.2. SDA increased asymptotically with ingested meal size for all diets.
• 3.3. Body weight had a significant positive effect on SDA for only one of the six diets tested, but weak tendencies were present in the data for the other diets.
• 4.4. SDA appeared to increase geometrically with increasing concentration of amino acids at high ration levels.

     

Towards an explanation of specific dynamic action (SDA)

Of the hypotheses proposed to explain specific dynamic action (SDA), it is suggested that the 'protein synthesis/growth' theory offers the best basis for further research. In the light of this, the relationships between rates of protein synthesis and metabolic rates are examined. Both of which are depressed with increasing periods of starvation and there appears to be a link between rates of protein synthesis and thyroid activity. SDA may represent a short-term increase in rates of protein synthesis and turnover following feeding and the process is possibly regulated via plasma levels of thyroid hormones.     

Detection of serum antibodies using LBC cell-grown sialodacryoadenitis (SDA) virus.

The TG strain of sialodacryoadenitis (SDA) virus propagated in LBC cell culture (TGr/LBC) reacted strongly with anti-TGr rat serum in complement fixation (CF) tests, showing much higher titers with anti-TGr rat serum than mouse hepatitis virus MHV-NuU antigen. The antigenicity was not affected after ether treatment while infectivity was lost. The TGr/LBC antigen might be useful in seromonitoring for SDA infection in rats.     

Multiplex strand displacement amplification (SDA) and detection of DNA sequences from Mycobacterium tuberculosis and other mycobacteria.

Strand Displacement Amplification (SDA) is an isothermal, in vitro method of amplifying a DNA target sequence prior to detection [Walker et al (1992) Nucleic Acids Res., 20, 1691-1693]. Here we describe a multiplex form of SDA that allows two target sequences and an internal amplification control to be co-amplified by a single pair of primers after common priming sequences are spontaneously appended to the ends of target fragments. Multiplex SDA operates at a single temperature, under the same simple protocol previously developed for single-target SDA. We applied multiplex SDA to co-amplification of a target sequence (IS6110) that is specific to members of the Mycobacterium tuberculosis-complex and a target (16S ribosomal gene) that is common to most clinically relevant species of mycobacteria. Both targets are amplified 10(8)-fold during a 2 hour, single temperature incubation. The relative sensitivity of the system was evaluated across a number of clinically relevant mycobacteria and checked for crossreactivity against organisms that are closely related to mycobacteria.     

The relationship between specific dynamic action (SDA) and growth in the common starfish,Asterias rubens L.

Summary After feeding the metabolic rate of animals rapidly increases to a peak level and thereafter slowly declines to pre-feeding level. This phenomenon has been termed the specific dynamic action of food. The processes causing the increase in metabolism are uncertain. In Asterias rubens there was a close relationship between the magnitude of SDA and growth rate (coefficient of determination=r ²=0.85), suggesting that the increased metabolic expenditure following feeding represent the energetic cost of growth.     

Phytophthora capsici homologue of the cell cycle regulator SDA1 is required for sporangial morphology,mycelial growth and plant infection

SDA1 encodes a highly conserved protein that is widely distributed in eukaryotic organisms. SDA1 is essential for cell cycle progression and organization of the actin cytoskeleton in yeasts and humans. In this study, we identified a Phytophthora capsici orthologue of yeast SDA1, named PcSDA1. In P. capsici, PcSDA1 is strongly expressed in three asexual developmental states (mycelium, sporangia and germinating cysts), as well as late in infection. Silencing or overexpression of PcSDA1 in P. capsici transformants affected the growth of hyphae and sporangiophores, sporangial development, cyst germination and zoospore release. Phalloidin staining confirmed that PcSDA1 is required for organization of the actin cytoskeleton. Moreover, 4′,6‐diamidino‐2‐phenylindole (DAPI) staining and PcSDA1‐green fluorescent protein (GFP) fusions revealed that PcSDA1 is involved in the regulation of nuclear distribution in hyphae and sporangia. Both silenced and overexpression transformants showed severely diminished virulence. Thus, our results suggest that PcSDA1 plays a similar role in the regulation of the actin cytoskeleton and nuclear division in this filamentous organism as in non‐filamentous yeasts and human cells.     

Effects of Hypoxic Exposure during Feeding on SDA and Postprandial Cardiovascular Physiology in the Atlantic Cod,Gadus morhua

Some Atlantic cod in the Bornholm Basin undertake vertical foraging migrations into severely hypoxic bottom water. Hypoxic conditions can reduce the postprandial increase in gastrointestinal blood flow (GBF). This could subsequently postpone or reduce the postprandial increase in oxygen consumption (MO₂), i.e. the SDA, leading to a disturbed digestion. Additionally, a restricted oxygen uptake could result in an oxygen debt that needs to be compensated for upon return to normoxic waters and this may also affect the ability to process the food. Long-term cardio-respiratory measurements were made on fed G. morhua in order to understand how the cardio-respiratory system of feeding fish respond to a period of hypoxia and a subsequent return to normoxia. These were exposed to 35% water oxygen saturation for 90 minutes, equivalent to the time and oxygen level cod voluntarily endure when searching for food in the Bornholm Basin. We found that i) gastric and intestinal blood flows, cardiac output and MO₂ increased after feeding, ii) gastric and intestinal blood flows were spared in hypoxia, and iii) there were no indications of an oxygen debt at the end of the hypoxic period. The magnitude and time course of the measured variables are similar to values obtained from fish not exposed to the hypoxic period. In conclusion, when cod in the field search for and ingest prey under moderate hypoxic conditions they appear to stay within safe limits of oxygen availability as we saw no indications of an oxygen debt, or negative influence on digestive capacity, when simulating field observations.     

Real-time monitoring of the strand displacement amplification (SDA) of human cytomegalovirus by a new SDA-piezoelectric DNA sensor system

Nucleic acid amplification has long been used in biosensor technologies, such as DNA sensors, DNA chips and microarrays, due to its advantage of high sensitivity in detecting target DNA. However, dynamic monitoring of nucleic acid amplifications with traditional DNA sensors in real-time is difficult since a constant temperature must be maintained during detection. Thus, the piezoelectric sensor, one type of traditional DNA sensor, is not applicable in real-time monitoring PCR due to the dramatic change in temperature that occurs during reaction. In this study, we introduced strand displacement amplification (SDA), an well-developed nucleic acid amplification technique that can work under conditions of constant temperature, into the development of a novel piezoelectric sensor. Using the new SDA-piezoelectric DNA sensor, we designed a stable system for liquid-phase detection, in which the crystal oscillator plate was fixed by an easily adjustable screw-threaded clamping mechanism and successfully applied the new sensor system to real-time SDA monitoring of human cytomegalovirus (HCMV). This new technique overcomes the shortcomings of traditional DNA sensors in real-time monitoring of nucleic acid amplification. The technique has proved to be a markedly simplified procedure with a number of advantages, such as higher sensitivity, better time efficiency, and the ability of dynamic real-time detection.     

Does specific dynamic action (SDA) regulate return of appetite in the lesser spotted dogfish,Scyliorhinus caniculcla?

Specific dynamic action (SDA) and the return of appetite (RA) were measured in juvenile (weight range 10·9–16·3 g) and adult (weight range 588·8–802·2 g) Scyliorhinus canicula by means of respirometry and re-feeding trials respectively. Juvenile S. canicula consumed relatively more food than the adults at all times indicating faster rates of food processing in juvenile dogfish. At no time during the SDA effect was there any evidence that elevated levels of oxygen consumption completely prevented further food consumption in either adult or juvenile dogfish. The coefficient (Duration_SDA/Duration_RA) was similar for both adult (0·52) and juvenile (0·49) S. canicula suggesting that SDA metabolism was closely associated with the processes involved in appetite return.     

SDA,a DNA Aptamer Inhibiting E- and P-Selectin Mediated Adhesion of Cancer and Leukemia Cells,the First and Pivotal Step in Transendothelial Migration during Metastasis Formation

Endothelial (E-) and platelet (P-) selectin mediated adhesion of tumor cells to vascular endothelium is a pivotal step of hematogenous metastasis formation. Recent studies have demonstrated that selectin deficiency significantly reduces metastasis formation in vivo. We selected an E- and P-Selectin specific DNA Aptamer (SDA) via SELEX (Systematic Evolution of Ligands by EXponential enrichment) with a K _d value of approximately 100 nM and the capability of inhibiting the interaction between selectin and its ligands. Employing human colorectal cancer (HT29) and leukemia (EOL-1) cell lines we could demonstrate an anti-adhesive effect for SDA in vitro. Under physiological shear stress conditions in a laminar flow adhesion assay, SDA inhibited dynamic tumor cell adhesion to immobilized E- or P-selectin. The stability of SDA for more than two hours allowed its application in cell-cell adhesion assays in cell culture medium. When adhesion of HT29 cells to TNFα-stimulated E-selectin presenting human pulmonary microvascular endothelial cells was analyzed, inhibition via SDA could be demonstrated as well. In conclusion, SDA is a potential new therapeutic agent that antagonizes selectin-mediated adhesion during metastasis formation in human malignancies.     

Suitability of genomic DNA synthesized by strand displacement amplification (SDA) for AFLP analysis: genotyping single spores of arbuscular mycorrhizal (AM) fungi

Limited biological samples of microbial origin often yield insufficient amounts of genomic DNA, making application of standard techniques of genetic analysis, like amplified fragment length polymorphism (AFLP), virtually impossible. The Phi29 DNA polymerase based whole genome amplification (WGA) method has the potential to alleviate this technical bottleneck. In the present work, we have sought to investigate the suitability of genomic DNA synthesized using Phi29 based WGA for AFLP analysis. We first used genomic DNA from Saccharomyces cerevisiae to optimize the protocol for the use of SDA-amplified DNA for AFLP analysis. Based on the optimized protocol we obtained AFLP fingerprints which were indistinguishable from the non-amplified genomic DNA. Finally, AFLP analysis was performed using SDA synthesized genomic DNA from single spores of various species of arbuscular mycorrhizal (AM) fungi. Unique and highly reproducible fingerprints for each species were obtained. The present study introduces the application of WGA-mediated AFLP to AM fungal biology; similarly, our protocol could be useful for other microbial genomes currently not amenable to genetic analysis owing to the paucity of starting template.