Collection and culture of live foods for aquaculture in Taiwan

Collection and culture of live foods to be used instudies of feeds for rearing finfish and shellfishlarvae in Taiwan began in 1982. Today, 31 species (49strains) of microalgae, three species (nine strains)of rotifers, one cladoceran and one copepod are holdas start culture. Microalgae are collected from localwaters and obtained from foreign collection centers.The most common genera are Chlorella,Nannochloropsis, Tetraselmis, Chaetoceros, Skeletonema, Isochrysis, and Pavlova. Someinteresting genera such as Ellipsoidion,Nannochloris, Synechococcus, and Alexandriumare also included. Three types of rotifers, i.e. L, S,and SS-type, which are classified as Brachionusplicatilis, B. rotundiformis, and Brachionus sp. are found in Taiwan waters. Among therotifers, six strains have been isolated and cultured.Another L-type strain and two SS-type strains wereobtained from foreign sources. The cladoceran Diaphanosoma aspinosum and copepod Apocyclopsroyi are the most common species used in aquaculture.Studies of live foods including their morphology,culture techniques, fatty acid composition andnutritional value as feeds have been undertaken.     

Expression of a gene encoding β‐ureidopropionase is critical for pollen germination in tomatoes

Global warming has seriously decreased world crop yield. High temperatures affect development, growth and, particularly, reproductive tissues in plants. A gene encoding β‐ureidopropionase (SlUPB1, EC 3.5.1.6) was isolated from the stamens of a heat‐tolerant tomato (CL5915) using suppression subtractive hybridization. SlUPB1 catalyzes the production of β‐alanine, the only β‐form amino acid in nature. In the anthesis stage, SlUPB1 expression in CL5915 stamens, growing at 35/30°C (day/night), was 2.16 and 2.93 times greater than that in a heat‐sensitive tomato (L4783) cultivated at 30/25°C or 25/20°C, respectively. Transgenic tomatoes, upregulating SlUPB1 in L4783 and downregulating SlUPB1 in CL5915, were constructed, and the amount of β‐alanine measured by liquid chromatography‐electrospray ionization‐mass spectrometry in the transgenic overexpression of SlUPB1 was higher than that of L4783. However, the β‐alanine in the transgenics downregulating SlUPB1 was significantly lower than the β‐alanine of CL5915. Pollen germination rates of these transgenics were analyzed under different developmental and germinating temperatures. The results indicated that germination rates of transgenics overexpressing SlUPB1 were higher than germination rates of the background tomato L4783. Germination rates of transgenics downregulating SlUPB1 were significantly lower than germination rates of background tomato CL5915, indicating the necessity of functional SlUPB1 for pollen germination. Pollen germinating in the buffer with the addition of β‐alanine further indicated that β‐alanine effectively enhanced pollen germination in tomatoes with low SlUPB1 expression. Together, these results showed that the expression of SlUPB1 is important for pollen germination, and β‐alanine may play a role in pollen germination under both optimal and high temperatures.     

Effects of elevated CO2 and temperature on the growth,elemental composition,and cell size of two marine diatoms: potential implications of global climate change

Two pennate diatoms, Amphora coffeaeformis and Nitzschia ovalis, were used to evaluate potential responses to the future CO₂ and temperature increases with respect to cell-specific growth rate, elemental composition, size, population growth rate, and carrying capacity. Diatoms were subjected to four different treatments over a 2 week period (approximately 4 generations): a control (28°C and present-day CO₂, ~400 ppm), high CO₂ (28°C with high CO₂, ~750 ppm), high temperature (31°C and present-day CO₂, ~400 ppm), and greenhouse-effect treatment (31°C with high CO₂, ~750 ppm). The results indicated that both the cell-specific growth rates and the carrying capacity of A. coffeaeformis decreased at the higher temperature treatment, whereas N. ovalis did not differ among all treatments. No significant difference was found in either species’ elemental cell composition, but higher C:N and C:P ratios were observed for A. coffeaeformis and N. ovalis, respectively, in high CO₂ and greenhouse-effect treatments. Smaller cell sizes were observed for both species under the greenhouse-effect treatment, a phenomenon that could alter benthic food webs in the future.     

LL-37 Peptide Enhancement of Signal Transduction by Toll-like Receptor 3 Is Regulated by pH: IDENTIFICATION OF A PEPTIDE ANTAGONIST OF LL-37

LL-37 is a peptide secreted by human epithelial cells that can lyse bacteria, suppress signaling by Toll-like receptor 4 (TLR4), and enhance signaling to double-stranded RNA (dsRNA) by TLR3. How LL-37 interacts with dsRNA to affect signal transduction by TLR3 is not completely understood. We determined that LL-37 binds dsRNA and traffics to endosomes and releases the dsRNA in a pH-dependent manner. Using dynamic light scattering spectroscopy and cell-based FRET experiments, LL-37 was found to form higher order complexes independent of dsRNA binding. Upon acidification LL-37 will dissociate from a larger complex. In cells, LL-37 has a half-live of ∼1 h. LL-37 half-life was increased by inhibiting endosome acidification or inhibiting cathepsins, which include proteases whose activity are activated by endosome acidification. Residues in LL-37 that contact poly(I:C) and facilitate oligomerization in vitro were mapped. Peptide LL-29, which contains the oligomerization region of LL-37, inhibited LL-37 enhancement of TLR3 signal transduction. LL-29 prevented LL-37·poly(I:C) co-localization to endosomes containing TLR3. These results shed light on the requirements for LL-37 enhancement of TLR3 signaling.     

Calcium Movement in Cardiac Mitochondria

Existing theory suggests that mitochondria act as significant, dynamic buffers of cytosolic calcium ([Ca²⁺]_i) in heart. These buffers can remove up to one-third of the Ca²⁺ that enters the cytosol during the [Ca²⁺]_i transients that underlie contractions. However, few quantitative experiments have been presented to test this hypothesis. Here, we investigate the influence of Ca²⁺ movement across the inner mitochondrial membrane during both subcellular and global cellular cytosolic Ca²⁺ signals (i.e., Ca²⁺ sparks and [Ca²⁺]_i transients, respectively) in isolated rat cardiomyocytes. By rapidly turning off the mitochondria using depolarization of the inner mitochondrial membrane potential (ΔΨ_m), the role of the mitochondria in buffering cytosolic Ca²⁺ signals was investigated. We show here that rapid loss of ΔΨ_m leads to no significant changes in cytosolic Ca²⁺ signals. Second, we make direct measurements of mitochondrial [Ca²⁺] ([Ca²⁺]_m) using a mitochondrially targeted Ca²⁺ probe (MityCam) and these data suggest that [Ca²⁺]_m is near the [Ca²⁺]_i level (∼100 nM) under quiescent conditions. These two findings indicate that although the mitochondrial matrix is fully buffer-capable under quiescent conditions, it does not function as a significant dynamic buffer during physiological Ca²⁺ signaling. Finally, quantitative analysis using a computational model of mitochondrial Ca²⁺ cycling suggests that mitochondrial Ca²⁺ uptake would need to be at least ∼100-fold greater than the current estimates of Ca²⁺ influx for mitochondria to influence measurably cytosolic [Ca²⁺] signals under physiological conditions. Combined, these experiments and computational investigations show that mitochondrial Ca²⁺ uptake does not significantly alter cytosolic Ca²⁺ signals under normal conditions and indicates that mitochondria do not act as important dynamic buffers of [Ca²⁺]_i under physiological conditions in heart.     

Calcium Movement in Cardiac Mitochondria

Existing theory suggests that mitochondria act as significant, dynamic buffers of cytosolic calcium ([Ca²⁺]_i) in heart. These buffers can remove up to one-third of the Ca²⁺ that enters the cytosol during the [Ca²⁺]_i transients that underlie contractions. However, few quantitative experiments have been presented to test this hypothesis. Here, we investigate the influence of Ca²⁺ movement across the inner mitochondrial membrane during both subcellular and global cellular cytosolic Ca²⁺ signals (i.e., Ca²⁺ sparks and [Ca²⁺]_i transients, respectively) in isolated rat cardiomyocytes. By rapidly turning off the mitochondria using depolarization of the inner mitochondrial membrane potential (ΔΨ_m), the role of the mitochondria in buffering cytosolic Ca²⁺ signals was investigated. We show here that rapid loss of ΔΨ_m leads to no significant changes in cytosolic Ca²⁺ signals. Second, we make direct measurements of mitochondrial [Ca²⁺] ([Ca²⁺]_m) using a mitochondrially targeted Ca²⁺ probe (MityCam) and these data suggest that [Ca²⁺]_m is near the [Ca²⁺]_i level (∼100 nM) under quiescent conditions. These two findings indicate that although the mitochondrial matrix is fully buffer-capable under quiescent conditions, it does not function as a significant dynamic buffer during physiological Ca²⁺ signaling. Finally, quantitative analysis using a computational model of mitochondrial Ca²⁺ cycling suggests that mitochondrial Ca²⁺ uptake would need to be at least ∼100-fold greater than the current estimates of Ca²⁺ influx for mitochondria to influence measurably cytosolic [Ca²⁺] signals under physiological conditions. Combined, these experiments and computational investigations show that mitochondrial Ca²⁺ uptake does not significantly alter cytosolic Ca²⁺ signals under normal conditions and indicates that mitochondria do not act as important dynamic buffers of [Ca²⁺]_i under physiological conditions in heart.     

Ethanol-Induced Upregulation of 10-Formyltetrahydrofolate Dehydrogenase Helps Relieve Ethanol-Induced Oxidative Stress

Alcoholism induces folate deficiency and increases the risk for embryonic anomalies. However, the interplay between ethanol exposure and embryonic folate status remains unclear. To investigate how ethanol exposure affects embryonic folate status and one-carbon homeostasis, we incubated zebrafish embryos in ethanol and analyzed embryonic folate content and folate enzyme expression. Exposure to 2% ethanol did not change embryonic total folate content but increased the tetrahydrofolate level approximately 1.5-fold. The expression of 10-formyltetrahydrofolate dehydrogenase (FDH), a potential intracellular tetrahydrofolate reservoir, was increased in both mRNA and protein levels. Overexpressing recombinant FDH in embryos alleviated the ethanol-induced oxidative stress in ethanol-exposed embryos. Further characterization of the zebrafish fdh promoter revealed that the −124/+40 promoter fragment was the minimal region required for transactivational activity. The results of site-directed mutagenesis and binding analysis revealed that Sp1 is involved in the basal level of expression of fdh but not in ethanol-induced upregulation of fdh. On the other hand, CEBPα was the protein that mediated the ethanol-induced upregulation of fdh, with an approximately 40-fold increase of fdh promoter activity when overexpressed in vitro. We concluded that upregulation of fdh involving CEBPα helps relieve embryonic oxidative stress induced by ethanol exposure.