Purple acid phosphatases (PAPs) are a family of metallo-phosphoesterases involved in a variety of physiological functions, especially phosphate deficiency adaptations in plants. We identified 26 putative PAP genes by a genome-wide analysis of rice (Oryza sativa), 24 of which have isolated EST sequences in the dbEST database. Amino acid sequence analysis revealed that 25 of these genes possess sets of metal-ligating residues typical of known PAPs. Phylogenetic analysis classified the 26 rice and 29 Arabidopsis PAPs into three main groups and seven subgroups. We detected transcripts of 21 PAP genes in roots or leaves of rice seedlings. The expression levels of ten PAP genes were up-regulated by both phosphate deprivation and over-expression of the transcription factor OsPHR2. These PAP genes all contained one or two OsPHR2 binding elements in their promoter regions, implying that they are directly regulated by OsPHR2. Both acid phosphatase (AP) and surface secretory acid phosphatase (SAP) activity assays showed that the up-regulation of PAPs by Pi starvation, OsPHR2 over-expression, PHO2 knockout or OsSPX1 RNA interference led to an increase in AP and SAP activity in rice roots. This study reveals the potential for developing technologies for crop improvement in phosphorus use efficiency.

Age determination is the basis of determining the postmortem interval using necrophagous fly larvae. To explore the potential of using cuticular hydrocarbons for determining the ages of fly larvae, changes of cuticular hydrocarbons in developing larvae of Chrysomya rufifacies (Macquart) (Diptera: Calliphoridae) were investigated using gas chromatography with flame-ionization detection and gas chromatography-mass spectrometry. This study showed that the larvae produced cuticular hydrocarbons typical of insects. Most of the hydrocarbons identified were alkanes with the carbon chain length of 21-31, plus six kinds of alkenes. The hydrocarbon composition of the larvae correlated with age. The statistical results showed that simple peak ratios of n-C29 divided by another eight selected peaks increased significantly with age; their relationships with age could be modelled using exponential or power functions with R(2) close to or > 0.80. These results suggest that cuticular hydrocarbon composition is a useful indicator for determining the age of larval C. rufifacies, especially for post-feeding larvae, which are difficult to differentiate by morphology.

The dielectric and ferroelectric characteristics of (Sr x Ba 1x ) Nb 2 O 6 unfilled tungsten bronze ceramics have been investigated together with the structure. The dielectric and ferroelectric characteristics of the present ceramics vary significantly with x, and the A1/A2-sites occupancy has been determined as the primary parameter governing this variation tendency. Ba ions tend to occupy A2-sites, Sr ions tend to occupy A1-sites, and one A1-site is empty. When the ratio of Sr/Ba is close to 1:4 (where four A2-sites are just occupied by Ba ions, and one A1-site is occupied by Sr ion while another A1-site is empty), the normal ferroelectric transition is observed with one anomaly in the tand-T curve (x = 0.25). When the ratio of Sr/Ba is far away from 1:4, the typical relaxor behavior is indicated together with three anomalies in the tand-T curve (x = 0.75). The incommensurate oxygen octahedral tilting and A-site random distribution are considered to be the structure origins for the relaxor ferroelectricity and low temperature dielectric relaxations. D. Johnson-contributing editorManuscript No. 33482.

To assess the potential application of pteridine fluorescence in determining the age of adult Boettcherisca peregrina (Diptera: Sarcophagidae) Robineau-Desvoidy and further for the postmortem interval, the age-dependent changes of pteridine fluorescence were investigated for the adults maintained at five constant temperatures. From the results, significant linear relationships were found between pteridine fluorescence and the age of the adults maintained at 16, 20, 24, 28 or 32 °C (P < 0.001, r(2) > 0.85). In addition, the relationships between the rate of pteridine accumulation and temperature were well described using linear equations for adult females and males. Then for each cohort of the flies at the ambient temperature, a calendar was constructed and used to determine the ages of females and males, respectively, in which was recorded in reverse time order the amount of pteridine accumulated per hour by the flies and their expected pteridine level when they emerged at the specified time. A significant linear relationship between estimated ages and chronological ages was observed for female or male adults, with the mean errors of the estimated ages of ±1.82 days for females and ±1.58 days for males. It is suggested that pteridine fluorescence analysis has a potential value in determining the age of adult B. peregrina.