Use of digital webcam images to track spring green-up in a deciduous broadleaf forest

Understanding relationships between canopy structure and the seasonal dynamics of photosynthetic uptake of CO₂ by forest canopies requires improved knowledge of canopy phenology at eddy covariance flux tower sites. We investigated whether digital webcam images could be used to monitor the trajectory of spring green-up in a deciduous northern hardwood forest. A standard, commercially available webcam was mounted at the top of the eddy covariance tower at the Bartlett AmeriFlux site. Images were collected each day around midday. Red, green, and blue color channel brightness data for a 640 × 100-pixel region-of-interest were extracted from each image. We evaluated the green-up signal extracted from webcam images against changes in the fraction of incident photosynthetically active radiation that is absorbed by the canopy (f _APAR), a broadband normalized difference vegetation index (NDVI), and the light-saturated rate of canopy photosynthesis (A _max), inferred from eddy flux measurements. The relative brightness of the green channel (green %) was relatively stable through the winter months. A steady rising trend in green % began around day 120 and continued through day 160, at which point a stable plateau was reached. The relative brightness of the blue channel (blue %) also responded to spring green-up, although there was more day-to-day variation in the signal because blue % was more sensitive to changes in the quality (spectral distribution) of incident radiation. Seasonal changes in blue % were most similar to those in f _APAR and broadband NDVI, whereas changes in green % proceeded more slowly, and were drawn out over a longer period of time. Changes in A _max lagged green-up by at least a week. We conclude that webcams offer an inexpensive means by which phenological changes in the canopy state can be quantified. A network of cameras could offer a novel opportunity to implement a regional or national phenology monitoring program.     

Triggered release of ciprofloxacin from nanostructured agglomerated vesicles

Nanostructured agglomerated vesicles encapsulating ciprofloxacin were evaluated for modulated delivery from the lungs in a healthy rabbit model. An aliphatic disulfide crosslinker, cleavable by cysteine was used to form cross-links between nanosized liposomes to form the agglomerates. The blood levels of drug after pulmonary instillation of free ciprofloxacin, liposomal ciprofloxacin, and the agglomerated liposomes encapsulating ciprofloxacin were evaluated. The liposomes and agglomerated vesicles showed extended release of drug into the blood over 24 hours, while the free ciprofloxacin did not. The agglomerates also allowed modulation of the drug release rate upon the introduction of cysteine into the lungs post-drug instillation; the cysteine-cleavable agglomerates accelerated their drug release rate, indicated by an increased level of drug in the blood. This technology holds promise for the post-administration modulation of antibiotic release, for the prevention and treatment of pulmonary and systemic infections.     

Observations of wild hunting behaviour and bioluminescence of a large deep-sea, eight-armed squid, Taningia danae

Our newly developed underwater high definition video camera system took the first live images of adults of the mesopelagic large squid, Taningia danae, between 240 and 940 m deep off Ogasawara Islands, western North Pacific. The resulting footage includes attacking and bioluminescence behaviours, and reveals that T. danae is far from the sluggish neutrally buoyant deep-sea squid previously suspected. It can actively swim both forward and backward freely by flapping its large muscular triangular fins and changes direction quickly through bending its flexible body. It can attain speeds of 2-2.5 ms(-1) (7.2-9 km h(-1)) when attacking bait rigs. They emitted short bright light flashes from their large arm-tip photophores before final assault, which might act as a blinding flash for prey as well as a means of measuring target distance in a dark deep-sea environment. They also emitted long and short glows separated by intervals while wandering around the double torch lights attached to the bait rig, suggestive of potential courtship behaviours during mating.     

Determination of the minimal fusion peptide of bovine leukemia virus gp30

In this study, we determined the minimal N-terminal fusion peptide of the gp30 of the bovine leukemia virus on the basis of the tilted peptide theory. We first used molecular modelling to predict that the gp30 minimal fusion peptide corresponds to the 15 first residues. Liposome lipid-mixing and leakage assays confirmed that the 15-residue long peptide induces fusion in vitro and that it is the shortest peptide inducing optimal fusion since longer peptides destabilize liposomes to the same extent but not shorter ones. The 15-residue long peptide can thus be considered as the minimal fusion peptide. The effect of mutations reported in the literature was also investigated. Interestingly, mutations related to glycoproteins unable to induce syncytia in cell-cell fusion assays correspond to peptides predicted as non-tilted. The relationship between obliquity and fusogenicity was also confirmed in vitro for one tilted and one non-tilted mutant peptide.     

Testing transgenic regulatory elements through live mouse imaging

To overcome positional and methylation effects on transgene expression, we developed a universal cloning cassette for in vivo assessment of regulatory elements using the luciferase reporter gene and the CCCD camera. Monitoring luciferase expression pattern in live mice enables screening of large numbers of transgenic founders quickly and inexpensively. We demonstrate that in the engineered transgenic mice, the chicken beta-globin 5'HS4 insulator did not always provide the desirable expression pattern, and the Island Element, responsible for the demethylation of the surrounding DNA region, was not beneficial. Both tested liver-specific and developmentally regulated promoters exhibited the expected expression pattern in most transgenic founders.     

Water near lipid membranes as seen by infrared spectroscopy

The ordering and H-bonding characteristics of the hydration water of the lipid 1-palmitoyl-2-oleoylphosphatidylcholine (POPC) were studied using polarized infrared spectroscopy by varying either the temperature or the relative humidity of the ambient atmosphere of multibilayer samples. The OH-stretching band of lipid-bound water was interpreted by a simplified two-state model of well-structured, low density “network” water and of less-structured dense “multimer” water. The IR-spectroscopic data reflect a rather continuous change of the water properties with increasing distance from the membrane and with changing temperature. Network and multimer water distribute across the whole polar interphase with changing composition and orientation. Upon dehydration the fraction of network water increases from about 30 to 60%, a value which is similar to that in supercooled water at −25°C. The highly ordered gel phase gives rise to an increased fraction of structured network water compared with the liquid crystalline phase. The IR order parameter shows that the water dipoles rearrange from a more parallel towards a more perpendicular orientation with respect to the membrane normal with progressive hydration. Dedicated to Prof. K. Arnold on the occasion of his 65th birthday.     

Turning pyridoxal-5'-phosphate-dependent enzymes into thermostable binding proteins: D-Serine dehydratase from baker's yeast as a case study

D-serine dehydratase from Saccharomyces cerevisae is a recently discovered dimeric enzyme catalyzing the β-elimination of D-serine to pyruvate and ammonia. The reaction is highly enantioselective and depends on cofactor pyridoxal-5'-phosphate (PLP) and Zn(2+). In our work, the aldimine linkage tethering PLP to recombinant, tagged D-serine dehydratase (Dsd) has been reduced by treatment with NaBH(4) so as to yield an inactive form of the holoenzyme (DsdR), which was further treated with a protease in order to remove the amino-terminal purification tag. Fourier Transform infrared (FT-IR) spectroscopic analysis revealed that both the reduced form (DsdR) and the reduced/detagged form (DsdRD) maintain the overall secondary structure of Dsd, but featured a significant increased thermal stability. The observed T(m) values for DsdR and for DsdRD shifted to 71.5 °C and 73.3 °C, respectively, resulting in nearly 11 °C and 13 °C higher than the one measured for Dsd. Furthermore, the analysis of the FT-IR spectra acquired in the presence of D-serine and L-serine indicates that, though catalytically inert, DsdRD retains the ability to enantioselectively bind its natural substrate. Sequence analysis of D-serine dehydratase and other PLP-dependent enzymes also highlighted critical residues involved in PLP binding. In virtue of its intrinsic properties, DsdRD represents an ideal candidate for the design of novel platforms based on stable, non-consuming binding proteins aimed at measuring d-serine levels in biological fluids.     

红外吸收法检测西林瓶包装冻干制品中的氧含量

目的应用HSA-P型激光检漏仪建立西林瓶包装冻干制品中氧气含量的测定方法。方法考察冻干制品中氧含量测定的操作条件:标准样瓶对仪器的校准;氮气吹扫前后样品中氧含量值的比较;不同纯度氮气吹扫标准样瓶后的氧含量值的变化。深化红外吸收法在测定西林瓶包装冻干疫苗中氧含量的应用。结果将该方法用于检测A群C群脑膜炎球菌多糖疫苗400批、麻疹减毒活疫苗86批、乙型脑炎减毒活疫苗46批,氧含量分别为1.64%±1.99%、1.36%±1.64%和0.99%±1.58%。结论该法测定冻干疫苗中的氧含量具有灵敏度高、速度快和易操作的优点,为冻干制品真空度的测定提供了定量检测方法。     

Studying Large Mammals With Imperfect Detection: Status and Habitat Preferences of Wild Cattle and Large Carnivores in Eastern Cambodia

Studying large mammal species in tropical forests is a conservation challenge with species’ behavior and ecology often increasing the probability of non‐detection during surveys. Consequently, knowledge of the distribution, status, and natural history of many large mammal species in Southeast Asia is limited. I developed occupancy models from camera‐trapping data, thereby accounting for imperfect detection at sampling sites, to clarify the status and habitat requirements of four globally threatened or near threatened large mammals (banteng Bos javanicus, gaur Bos gaurus, dhole Cuon alpinus, and leopard Panthera pardus) in Mondulkiri Protected Forest, eastern Cambodia. Camera traps were operational for >3500 trap nights with 202 photographic encounters of the four study species. Model averaged occupancy estimates were between 5 percent (leopard) and 140 percent (gaur) higher than naive estimates (i.e., proportion of camera‐trap sites species recorded from) thus highlighting the importance of accounting for detectability during conservation surveys. I recommend the use of an occupancy framework when using camera‐trap data to study the status, ecology, and habitat preferences of poorly known and elusive species. The results highlight the importance of mixed deciduous and semi‐evergreen forest for wild cattle in eastern Cambodia and I emphasize that these habitats must be considered in conservation planning across the Lower Mekong Dry Forest Ecoregion.