Potassium antimonate was used to locate loosely bound calcium in the stigma and style of tobacco. The tobacco stigma is wet and covered by a thick layer of glycoprotein exudate at anthesis. The exudate contains abundant vesicles, which are densely labeled with calcium precipitates. When pollen grains arrive at the stigma, become hydrated, and as the pollen swells, Ca(2+) precipitates accumulate at the aperture. Calcium precipitates that accumulate in pollen cytoplasm are initially concentrated within small vacuoles, but as germination proceeds these appear to fuse, forming prominent, densely labeled vesicles that preferentially accumulate near the proximal region of the growing tube. Although the stigma has abundant particles, few calcium precipitates are observed in the transmitting tissue from anthesis to 11 h after pollination. However, at 22 h after pollination, accumulation of calcium increases distally from the stigmatic interface with the transmitting tissue through the length of the style to the ovary. An examination of flowering plants with differing floral biology will be needed to understand the role of loosely bound calcium accumulation and its relationship to tissue-level changes in calcium uptake, maintenance of other calcium pools, including [Ca(2+)](cyt), and in pollen and style maturation during the progamic phase.

Caffeine is a major component of xanthine alkaloids and commonly consumed in many popular beverages. Due to its occasional side effects, reduction of caffeine in a natural way is of great importance and economic significance. Recent studies reveal that caffeine can be converted into non-stimulatory theacrine in the rare tea plant Camellia assamica var. kucha (Kucha), which involves oxidation at the C8 and methylation at the N9 positions of caffeine. However, the underlying molecular mechanism remains unclear. Here, we identify the theacrine synthase CkTcS from Kucha, which possesses novel N9-methyltransferase activity using 1,3,7-trimethyluric acid but not caffeine as a substrate, confirming that C8 oxidation takes place prior to N9-methylation. The crystal structure of the CkTcS complex reveals the key residues that are required for the N9-methylation, providing insights into how caffeine N-methyltransferases in tea plants have evolved to catalyze regioselective N-methylation through fine tuning of their active sites. These results may guide the future development of decaffeinated drinks.

Potassium pyroantimonate was used to localize loosely-bound calcium in young ovules of lettuce (Lactuca sativa L.) during megasporogenesis to investigate the relationship between ionically available calcium and megaspore degeneration. At the megasporocyte (megaspore mother cell) stage, few calcium precipitates were located in the ovule. Following meiosis in the megasporocyte, a linear tetrad of four megaspores is formed, with three of the four megaspores degenerating from the micropylar end inward. Only the chalazal-most megaspore continues to develop, becoming the functional megaspore. A decrease in amount of calcium precipitates in the megaspore, particularly in the nucleus, precedes the breakdown of the micropylar megaspores, which subsequently undergo structural disintegration and loss of recognizable cellular features. A partial recovery of calcium precipitates occurs during later degeneration. The functional megaspore retains a consistently higher concentration of calcium precipitates during development, which is retained in the developing embryo sac. This, to our knowledge, is the first report related to calcium dynamics during megaspore degeneration, and may facilitate future research aimed at elucidating the mechanisms of megasporogenesis

The cryoprotective effects of trehalose, alginate, and its oligosaccharide on cooked shrimp were evaluated and compared with Na4P2O7 during frozen storage. Data indicated that significant inhibitory effects on decreases of water‐holding capacity, water content, water activity, springiness, and chewiness values were more pronounced in trehalose‐, alginate oligosaccharide‐, and Na4P2O7‐treated samples than in freshwater‐treated samples. L* value analysis indicated that the saccharide‐soaking‐treatments showed positive effects on color stability of cooked shrimp. H&E and SEM studies indicated that the fibers of cooked shrimp from trehalose‐ and alginate‐oligosaccharide‐treated groups were arranged in a tighter manner than the control, and the extracellular space was significantly smaller than in control samples after 6 weeks of storage. The cryoprotective effects described above were probably due to the replacement of water molecules, concentration of water molecules near protein surface, ionic cross‐linking action in muscle, or stability of tissue structures derived from trehalose and oligosaccharide in shrimp muscle. Practical Applications Frozen storage is the most common method for long‐term preservation of cooked‐shrimp products. However, some undesirable changes can occur during freeze/thaw process, such as protein denaturation, lipid oxidation, and decreased water‐holding ability. Phosphates are widely used in shrimp products to reduce cooking loss, improve textural properties, increase water‐holding capacity (WHC), retard oxidative rancidity, and develop color. However, excessive phosphate treatment may not only cause phosphate imbalance in the diet, which poses health concerns, but also decreases quality by rendering the shrimp translucent or crispy. For this reason, alternative additives that can retain water and reduce drip loss should be considered to minimize degradation and improve the quality of the shrimp products. This study provides information regarding the cryoprotective effects of saccharides on peeled cooked‐shrimp during frozen storage. This application is of utmost interest, and might have widespread applications to extend the commercialization of refrigerated seafood to better guarantee quality and safety.

Bradysia odoriphaga Yang & Zhang (Diptera: Sciaridae) is an important pest of Chinese chives. Information on the effects of biotic and abiotic factors on the flight performance of B. odoriphaga is crucial for understanding the pest’s ability to disperse and migrate. In this study, the effects of sex and air temperature on the flight performance of B. odoriphaga imagoes were assessed by tethering individual imagoes to computerized flight mills for a 10-h experiment. The results showed that the percentage of imagoes that flew a particular distance gradually decreased as flight distance increased. The percentage of imagoes was significantly higher for males than females when the flight distance was <300 m. Sex and air temperature significantly affected average flight time (which ranged from 14.6 to 68.3 min) and average flight distance (which ranged from 10.4 to 107.2 m), but did not significantly affect average flight speed (which ranged from 3.8 to 6.4 m/min). For both females and males, the average flight distance and flight time were shortest at 18°C and longest at 22°C; the interaction between air temperature and sex was not significant. The results suggest that B. odoriphaga has a poor potential for long-distance migration. These findings will be helpful for developing forecasting and management systems for B. odoriphaga.