Comparison of Chlorophyll Meter Readings with Leaf Chlorophyll Concentration in Amaranthus vlitus: Correlation with Physiological Processes1

The portable chlorophyll meter (SPAD-502) has been successfully used for a rapid and direct estimation of total chlorophyll content (TCHL) in the leaves of some crops. In this work, SPAD-502 meter readings and TCHL concentration were compared for the leaves of Amaranthus vlitus L., a common weed. SPAD readings were linearly and positively correlated to TCHL concentration in the leaves. A linear correlation was also shown between SPAD-502 readings and some physiological parameters of the leaves, such as photosynthesis, transpiration, and stomatal conductance.     

An inexpensive,automatic gas meter for laboratory-scale methane digesters and other gas-evolving systems

A reliable and inexpensive system for measuring gas flow-rates and kinetics which is based on water displacement by gas in a burette is described. It can easily be couple to an acquisition system for data processing. This system allows the gas to be stored without changing the pressure in the gas producing digester and is able to record flow-rates lower than 1 ml · min^?1.     

A Simple Method of Obtaining Ultrathin-Sections from a Semithin-Section

The Epon-812 semithin-section, which had been observed under light microscope, was stuck to a trimmed resin block with 502 instant glue and was ultrasectioned for electron microscopy. This method, which is simple and tepid, gives a good result and may solve some problems happened in ultrasectioning some special material which needs to be exactly located.     

Hydraulic conductivity of red oak (Quercus rubra L.) leaf tissue does not respond to light

The permeability of leaf tissue to water has been reported to increase under illumination, a response reputed to involve aquaporins. We studied this ‘light response’ in red oak (Quercus rubra L.), the species in which the phenomenon was first detected during measurements of leaf hydraulic conductance with the high‐pressure flow meter (HPFM). In our HPFM measurements, we found that pre‐conditioning leaves in darkness was not sufficient to bring them to their minimum conductance, which was attained only after an hour of submersion and pressurization. However, pre‐conditioning leaves under anoxic conditions resulted in an immediate reduction in conductance. Leaves light‐ and dark‐acclimated while on the tree showed no differences in the time course of HPFM measurement under illumination. We also studied the effect of light level and anoxia on rehydration kinetics, finding that anoxia slowed rehydration, but light had no effect either in the lab (rehydration under low light, high humidity) or on the tree (acclimation under high light, 10 min of dark prior to rehydration). We conclude that the declines in conductance observed in the HPFM must involve a resistance downstream of the extracellular air space, and that in red oak the hydraulic conductivity of leaf tissue is insensitive to light.     

Florida Red Tide Toxins (Brevetoxins) and Longitudinal Respiratory Effects in Asthmatics

Having demonstrated significant and persistent adverse changes in pulmonary function for asthmatics after 1 h exposure to brevetoxins in Florida red tide (Karenia brevis bloom) aerosols, we assessed the possible longer term health effects in asthmatics from intermittent environmental exposure to brevetoxins over 7 years. 125 asthmatic subjects were assessed for their pulmonary function and reported symptoms before and after 1 h of environmental exposure to Florida red tide aerosols for up to 11 studies over seven years. As a group, the asthmatics came to the studies with normal standardized percent predicted pulmonary function values. The 38 asthmatics who participated in only one exposure study were more reactive compared to the 36 asthmatics who participated in ≥4 exposure studies. The 36 asthmatics participating in ≥4 exposure studies demonstrated no significant change in their standardized percent predicted pre-exposure pulmonary function over the 7 years of the study. These results indicate that stable asthmatics living in areas with intermittent Florida red tides do not exhibit chronic respiratory effects from intermittent environmental exposure to aerosolized brevetoxins over a 7 year period.     

Relationships between laboratory bioassay-derived potencies and field efficacies of Bacillus thuringiensis isolates with different spectral activities

Bacillus thuringiensis isolates with different spectral activities were not equally efficacious when applied to cabbage at the same number of IUs/ha for protection against larvae of the cabbage looper, Trichoplusia ni. Preparations of the isolates were standardized against T. ni larvae. Variety galleriae isolates (HD-196 and HD-153) were the most efficacious per applied IU, and a K-73 type variety kurstaki (HD-73) was the least efficacious per applied IU. A variety thuringiensis (HD-264) and a K-1 type variety kurstaki (HD-1) were intermediate in efficacy per applied IU. Speed of kill and, to some extent, differences in the amount of food consumed appear to be responsible for the differences in efficacy per applied IU. When more potent B. thuringiensis isolates are discovered and developed, the recommended field dosages for the new isolates must be determined by actual field experimentation rather than by extrapolation from existing HD-1 data.     

Spectral reflectance ratio of rice canopy for estimating crop nitrogen status

A portable meter for measuring the intensity of the green color of a rice canopy in the field by using spectral reflectance at 550 and 800 nm was newly devised. The measurements were found to be affected by reflection of sunshine on the leaf surface. With such limitations being taken into account, rice canopy green color intensity could be evaluated with this meter.     

The border fresidues of the dihydrofolate reductase domain inEscherichia coli β-galactosidase correspond to the positions of introns 1 and 5 of dihydrofolate reductase of chicken

Summary In-galactosidase ofEscherichia coli residues 820–934 are similar to residues in dihydrofolate reductase ofE. coli. Dihydrofolate reductase ofE. coli and chicken are also similar and have identical tertiary structures. I used the similarity of the three-dimensional structure of prokaryotic and eukaryotic dihydrofolage reductases to align the chicken dihydrofolate reductase and the similar residues of-galactosidase. The positions of introns 1 and 5 of the chicken dihydrofolate reductase gene correspond exactly to the start and the end of the dihydrofolate reductase-like domain in the-galactosidase polypeptide chain. This equivalence of intron positions in a eukaryotic gene and domain structure in a prokaryotic protein was interpreted as evidence for a common origin of both genes.     

Circular RNA circ_001842 plays an oncogenic role in renal cell carcinoma by disrupting microRNA‐502‐5p‐mediated inhibition of SLC39A14

Renal cell carcinoma (RCC) is a common urologic malignancy, and up to 30% of RCC patients present with locally advanced or metastatic disease at the time of initial diagnosis. Increasing evidence suggests that circular RNAs (circRNAs) serve as genomic regulatory molecules in various human cancers. Our initial in silico microarray‐based analysis identified that circRNA circ_001842 was highly expressed in RCC. Such up‐regulation of circ_001842 in RCC was experimentally validated in tissues and cell lines using RT‐qPCR. Thereafter, we attempted to identify the role of circ_001842 in the pathogenesis of RCC. Through a series of gain‐ and loss‐of function assays, cell biological functions were examined using colony formation assay, Transwell assay, annexin V‐FITC/PI‐labelled flow cytometry and scratch test. A high expression of circ_001842 in tissues was observed as associated with poor prognosis of RCC patients. circ_001842 was found to elevate SLC39A14 expression by binding to miR‐502‐5p, consequently resulting in augmented RCC cell proliferation, migration and invasion, as well as EMT in vitro and tumour growth in vivo. These observations imply the involvement of circ_001842 in RCC pathogenesis through a miR‐502‐5p‐dependent SLC39A14 mechanism, suggesting circ_001842 is a potential target for RCC treatment.     

Ectomycorrhizal symbiosis can enhance plant nutrition through improved access to discrete organic nutrient patches of high resource quality

It is known that roots can respond to patches of fertility; however, root proliferation is often too slow to exploit resources fully, and organic nutrient patches may be broken down and leached, immobilized or chemically fixed before they are invaded by the root system. The ability of fungal hyphae to exploit resource patches is far greater than that of roots due to their innate physiological and morphological plasticity, which allows comprehensive exploration and rapid colonization of resource patches in soils. The fungal symbionts of ectomycorrhizal plants excrete significant quantities of enzymes such as chitinases, phosphatases and proteases. These might allow the organic residue to be tapped directly for nutrients such as N and P. Pot experiments conducted with nutrient-stressed ectomycorrhizal and control willow plants showed that when high quality organic nutrient patches were added, they were colonized rapidly by the ectomycorrhizal mycelium. These established willows (0.5 m tall) were colonized by Hebeloma syrjense P. Karst. for 1 year prior to nutrient patch addition. Within days after patch addition, colour changes in the leaves of the mycorrhizal plants (reflecting improved nutrition) were apparent, and after I month the concentration of N and P in the foliage of mycorrhizal plants was significantly greater than that in non-mycorrhizal plants subject to the same nutrient addition. It seems likely that the mycorrhizal plants were able to compete effectively with the wider soil microbiota and tap directly into the high quality organic resource patch via their extra-radical mycelium. We hypothesize that ectomycorrhizal plants may reclaim some of the N and P invested in seed production by direct recycling from failed seeds in the soil. The rapid exploitation of similar discrete, transient, high-quality nutrient patches may have led to underestimations when determining the nutritional benefits of ectomycorrhizal colonization.