Breeding Ecology and Productivity of Red-Necked Grebes in Turtle Mountain Provincial Park, Manitoba

The breeding biology and productivity of the Red-necked Grebe (Podiceps grisegena) were studied in Turtle Mountain Provincial Park, Manitoba, during 1980 and 1981. Arrival dates ranged from mid-April to early June. Pre-nesting intervals ranged from 11 o 42 days and averaged about 20 days. Egg-laying commenced in early May and extended until mid-July. The average clutch size (4.95 eggs) was much larger than those found in other studies of the Red-necked Grebe in North America. Although the nest success rate was low (26.2%), most failed pairs (83.5%) initiated at least 1 replacement clutch, and more than one-half of the observed pairs successfully hatched 1 or more chicks. Predators, primarily the Raccoon (Procyon lotor), were believed responsible for about half of the egg losses. High residue levels of several pesticides, particularly DDE and PCBs, were believed to have contributed to the low nesting success. About one-quarter of the viability-tested eggs during this study were considered inviable. Ratcliffe indices revealed that thin-shelled eggs were produced and several cracked eggs were found. Average incubation periods calculated during this study (28-29 days) were longer than the 22-23 day incubation period generally recognized in the literature. Hatching occurred throughout June and July. Successful pairs hatched an average of 2.5 young, but raised only 1.9 young to the age of 1 month. High pesticide loads may have contributed to many of the losses that occurred during pre- and post-hatching stages. Later, intraspecific aggression probably contributed to significant differences in individual mortality rates within large and small broods. Because losses during the second month were minimal, Red-necked Grebes during this study fledged 1.8-1.9 young/successful pair or about 0.9 young/breeding pair

Calcium puffs are generic InsP₃-activated elementary calcium signals and are downregulated by prolonged hormonal stimulation to inhibit cellular calcium responses

Elementary Ca2+ signals, such as "Ca2+ puffs", which arise from the activation of inositol 1,4,5-trisphosphate receptors, are building blocks for local and global Ca2+ signalling. We characterized Ca2+ puffs in six cell types that expressed differing ratios of the three inositol 1,4,5-trisphosphate receptor isoforms. The amplitudes, spatial spreads and kinetics of the events were similar in each of the cell types. The resemblance of Ca2+ puffs in these cell types suggests that they are a generic elementary Ca2+ signal and, furthermore, that the different inositol 1,4,5-trisphosphate isoforms are functionally redundant at the level of subcellular Ca2+ signalling. Hormonal stimulation of SH-SY5Y neuroblastoma cells and HeLa cells for several hours downregulated inositol 1,4,5-trisphosphate expression and concomitantly altered the properties of the Ca2+ puffs. The amplitude and duration of Ca2+ puffs were substantially reduced. In addition, the number of Ca2+ puff sites active during the onset of a Ca2+ wave declined. The consequence of the changes in Ca2+ puff properties was that cells displayed a lower propensity to trigger regenerative Ca2+ waves. Therefore, Ca2+ puffs underlie inositol 1,4,5-trisphosphate signalling in diverse cell types and are focal points for regulation of cellular responses

Macro-meso-microsystems integration in LTCC : LDRD report.

Low Temperature Cofired Ceramic (LTCC) has proven to be an enabling medium for microsystem technologies, because of its desirable electrical, physical, and chemical properties coupled with its capability for rapid prototyping and scalable manufacturing of components. LTCC is viewed as an extension of hybrid microcircuits, and in that function it enables development, testing, and deployment of silicon microsystems. However, its versatility has allowed it to succeed as a microsystem medium in its own right, with applications in non-microelectronic meso-scale devices and in a range of sensor devices. Applications include silicon microfluidic ''chip-and-wire'' systems and fluid grid array (FGA)/microfluidic multichip modules using embedded channels in LTCC, and cofired electro-mechanical systems with moving parts. Both the microfluidic and mechanical system applications are enabled by sacrificial volume materials (SVM), which serve to create and maintain cavities and separation gaps during the lamination and cofiring process. SVMs consisting of thermally fugitive or partially inert materials are easily incorporated. Recognizing the premium on devices that are cofired rather than assembled, we report on functional-as-released and functional-as-fired moving parts. Additional applications for cofired transparent windows, some as small as an optical fiber, are also described. The applications described help pave the way for widespread application of LTCC to biomedical, control, analysis, characterization, and radio frequency (RF) functions for macro-meso-microsystems

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data