Two new sesterterpenoids from Atractylodes japonica Koidz. ex Kitam.

Two new sesterterpenoids, atractylodes japonica terpenoid acid I (1) and atractylodes japonica terpenoid aldehyde I (2), were isolated from the rhizomes of Atractylodes japonica Koidz. ex Kitam together with ten known compounds (3-12). Their structures were elucidated on the basis of comprehensive spectroscopic analysis (1D/2D NMR, HRESIMS and IR). In addition, all of these isolated compounds were evaluated for their cytotoxic activities against human gastric cancer cell MGC-803 and human hepatocellular cancer cell HepG-2. Most of them exhibited moderate to weak inhibitory effects with IC50 values in the range of 25.15-88.85 µM except for 9-12.

Two new diarylheptanoids from the green walnut husks of Juglans mandshurica Maxim.

Chemical investigation on the 95% ethanol extract of green walnut husks of Juglans mandshurica Maxim. led to the isolation of two new diarylheptanoid compounds, including Juglanin K (1) and Myricananin I (2), together with ten known compounds (3-13). Their structures were elucidated by extensive analyses of comprehensive spectroscopic methods. The isolated compounds were evaluated for their antibacterial activities against Escherichia coli and Staphylococcus aureus. The results showed that compound 2 had moderate antibacterial activity with the MIC values of 0.313 and 0.156 mg/mL, respectively. compounds 1, 3-7 and 13 showed weakly antibacterial activities against Escherichia coli and Staphylococcus aureus with the MIC values of 0.625-2.5 mg/mL.

Drought stress delays photosynthetic induction and accelerates photoinhibition under short-term fluctuating light in tomato.

Fluctuating light (FL) and drought stress usually occur concomitantly. However, whether drought stress affects photosynthetic performance under FL remains unknown. Here, we measured gas exchange, chlorophyll fluorescence, and P700 redox state under FL in drought-stressed tomato (Solanum lycopersicum) seedlings. Drought stress significantly delayed the induction kinetics of stomatal and mesophyll conductances after transition from low to high light and thus delayed photosynthetic induction under FL. Therefore, drought stress exacerbated the loss of carbon gain under FL. Furthermore, restriction of CO2 fixation under drought stress aggravated the over-reduction of photosystem I (PSI) upon transition from low to high light. The resulting stronger FL-induced PSI photoinhibition significantly suppressed linear electron flow and PSI photoprotection. These results indicated that drought stress not only caused a larger loss of carbon gain under FL but also accelerated FL-induced photoinhibition of PSI. Furthermore, drought stress enhanced relative cyclic electron flow in FL, which partially compensated for restricted CO2 fixation and thus favored PSI photoprotection under FL. To our knowledge, we here show new insight into how drought stress affects photosynthetic performance under FL.

Direct physical contact between intercalated cells in the distal convoluted tubule and the afferent arteriole in mouse kidneys.

Recent physiological studies in the kidney proposed the existence of a secondary feedback mechanism termed 'crosstalk' localized after the macula densa. This newly discovered crosstalk contact between the nephron tubule and its own afferent arteriole may potentially revolutionize our understanding of renal vascular resistance and electrolyte regulation. However, the nature of such a crosstalk mechanism is still debated due to a lack of direct and comprehensive morphological evidence. Its exact location along the nephron, its prevalence among the different types of nephrons, and the type of cells involved are yet unknown. To address these issues, computer assisted 3-dimensional nephron tracing was applied in combination with direct immunohistochemistry on plastic sections and electron microscopy. 'Random' contacts in the cortex were identified by the tracing and excluded. We investigated a total of 168 nephrons from all cortical regions. The results demonstrated that the crosstalk contact existed, and that it was only present in certain nephrons (90% of the short-looped and 75% of the long-looped nephrons). The crosstalk contacts always occurred at a specific position--the last 10% of the distal convoluted tubule. Importantly, we demonstrated, for the first time, that the cells found in the tubule wall at the contact site were always type nonA-nonB intercalated cells. In conclusion, the present work confirmed the existence of a post macula densa physical crosstalk contact.

A novel specific application of pyruvate protects the mouse retina against white light damage: differential stabilization of HIF-1α and HIF-2α.

PURPOSE: To mimic hypoxia preconditioning by a novel specific pyruvate treatment and to study its retinal protection against white light damage. METHODS: Six-to-eight-week-old BALB/c mice were exposed to strong white light calculated to produce photoreceptor degeneration. Some were given injections of pyruvate in a preordained protocol because evidence exists that proves pyruvate can affect the concentration of hypoxia inducible factor (HIF). Western blotting and real-time PCR were used to determine the concentration of proteins and mRNAs in retinas. Morphology was analyzed with toluidine blue staining and was plotted using a spidergraph. A free nucleosome cell death assay was used to examine apoptosis. Retina explant cultures were used to investigate the background mechanism. RESULTS: Pyruvate administration stabilized hypoxia inducible factor (HIF)-1α but not HIF-2α. Expression of the downstream genes hemoxygenase-1 and erythropoietin mirrored the changes of the two HIFs, respectively. Importantly, pyruvate given not only before but also after exposure to light protected photoreceptors against apoptosis. In the retinal explant system, addition or depletion of pyruvate caused only changes of HIF-1α and prolyl hydroxylase (PHD)-2, while HIF-2α and PHD1 were not affected. However, under hypoxic conditions, HIF-2α was stabilized by pyruvate but not HIF-1α. CONCLUSIONS: Pyruvate evoked a hypoxia-like response under normoxic conditions and was retina-protective against strong white light. This response included stabilization of HIF-1α but not HIF-2α. This differential stabilization might be related to the distinct preference of their degrading enzyme of PHD2 and PHD1 in response to pyruvate treatment.