An anatomical, ultrastructural, autoradiographic, and cytophotometric study of early embryo, endosperm, and ovule development in soybean (Glycine max L Merr)

Various aspects of early embryo, endosperm, and ovule development are described in soybean utilizing techniques in autoradiography, cytophotometry, image analysis, and light and electron microscopy. Pollen tube passage to the egg is facilitated by the break down of nucellar cells subtending the abfunicular synergid and degeneration of the latter prior to fertilization. Autoradiographic evidence indicates that the accumulation of [superscript]14C label assimilates within the ovular tissues is spatially and temporally regulated. At the zygote through proembryo stages, labeled assimilates enter the embryo sac micropylarly via the wandlabrinthe and chalazally via the hypostase. Nutrient movement into the lateral regions of the embryo sac seems to be blocked by a cuticle between the inner integument and embryo sac. At the globular embryo stage, the differentiation of the endothelium, fragmentation of the embryo sac cuticle, vascularization of the integuments, and the wall ingrowths of the cellular endosperm aid in the movement of label into the lateral regions of the embryo sac. Other features important in nutrient flux to the embryo are the: persistent acellular condition of the chalazal process; endospermic sheath surrounding the globular embryo; cuticle on the surface of the globular embryo but not on the suspensor; and transfer cell-like nature of the suspensor cells. Cellularization of the endosperm involves the formation of anticlinal sheet-like walls from the central cell wall. These walls fuse at their edges to form cylinders. Periclinal walls are laid down within the cylinders to form layers of endosperm cells centripetally. Degeneration of the endosperm appears to be an autolytic process and not due to physical breakage by the encroaching embryo. The mean size and ploidy condition (2C-4C) of the embryo nuclei is fairly stable at all stages studied. Only a few nuclei (3%) of the late heart-shaped embryo have ploidy levels above 4C. Free-nuclear endosperm nuclei are larger than those of the cellular endosperm. Most endosperm nuclei are in the expected 3C-6C ploidy range, but elevated ploidy levels are noted during endosperm cellularization. Endosperm senescence is correlated with nuclear DNA loss over time

On the Determinants of the Reach of Innovation-related Collaboration in Small Firms

This paper takes as its starting point an item of relatively recent academic orthodoxy: the insistence that ‘…interactive learning and collective entrepreneurship are fundamental to the process of innovation’ (Lundvall, 1992, p. 9). From this, academics have frequently taken “interactive” to imply “inter-organisational” and, whilst one might be concerned by this too casual conflation, there is a growing consensus that firms’ embeddedness in collaborative networks matters for their innovative performance (Gilsing et al., 2008).

Microscopic Characterization of a Transposon-Induced Male-Sterile, Female-Sterile Mutant in Glycine max L.

Premise of research. A male-sterile, female-sterile mutant was discovered in a w4-m mutable line of Glycine max L. The mechanism of its sterility was not well understood. Therefore, different cytological and microscopic techniques were undertaken to better understand the process of mutant phenotype development. Molecular research indicated that mer3 was responsible for the sterility. Methodology. Macro images were collected of whole plants, flowers, anthers, pods, and ovules. Chromosome spreads from anthers at various meiotic stages were examined. Confocal scanning laser microscopy using optical sectioning was utilized on whole anthers and ovules at various developmental stages. Whole mature anthers and isolated pollen images were collected and studied with SEM. Pivotal results. In observations of the mutant, male cell development was found to begin normally and then digresses at metaphase I of meiosis, when abnormal segregation of chromosomes with reduced bivalent formation was observed. It was the abnormal formation of univalents and bivalents that led to male sterility. On the female side, the progression of development was arrested in the megagametophyte stage likely because of abnormal meiosis, leading to ovule abortion and female sterility. Conclusions. The G. max male-sterile, female-sterile mutant was shown to have the same phenotype of mer3 sterility already shown in Arabidopsis, rice, yeast, and some animal systems

Potato Cultivar Differences Associated with Mealiness

Russet Burbank, Norchip, Pontiac, and LaSoda potato cultivars were examined for the parameters mealy and waxy. Russet Burbank was judged dry, hard and particulate, typifying mealiness. Using phase contrast microscopy and scanning electron microscopy, raw mealy cells were determined to be larger and more irregularly shaped than cells from waxy cultivars. Mealy cooked cells were engorged with gelatinized starch, cell walls were more polarized, and cell shapes were better retained after mashing, when compared to waxy cells. NMR-T2 bound water readings from Russet Burbank and Pontiac samples did not differ from each other. Starch granule sizes and shapes varied by cultivar

Faculty Ideals and Universities Third Mission

There is considerable variety in academics' attitudes towards universities' third mission. Research inactive faculty are more sympathetic to third mission goals than even applied research faculty. Women and younger colleagues are more ambivalent about the third mission. Faculty at universities that incentivise teaching tend towards a more positive attitude of the third mission. Private sector experience associates with third mission proclivities, not-for-profit experience associates with opposition

Panel options for large precision radio telescopes

The Cornell Caltech Atacama Telescope (CCAT) is a 25 m diameter telescope that will operate at wavelengths as short as 200 microns. CCAT will have active surface control to correct for gravitational and thermal distortions in the reflector support structure. The accuracy and stability of the reflector panels are critical to meeting the 10 micron HWFE (half wave front error) for the whole system. A system analysis based upon a versatile generic panel design has been developed and applied to numerous possible panel configurations. The error analysis includes the manufacturing errors plus the distortions from gravity, wind and thermal environment. The system performance as a function of panel size and construction material is presented. A compound panel approach is also described in which the reflecting surface is provided by tiles mounted on thermally stable and stiff sub-frames. This approach separates the function of providing an accurate reflecting surface from the requirement for a stable structure that is attached to the reflector support structure on three computer controlled actuators. The analysis indicates that there are several compound panel configurations that will easily meet the stringent CCAT requirements

IRC+10216's Innermost Envelope -- The eSMA's View

We used the Extended Submillimeter Array (eSMA) in its most extended configuration to investigate the innermost (within a radius of 290 R* from the star) circumstellar envelope (CSE) of IRC+10216. We imaged the CSE using HCN and other molecular lines with a beam size of 0."22 x 0."46, deeply into the very inner edge (15 R*) of the envelope where the expansion velocity is only 3 km/s. The excitation mechanism of hot HCN and KCl maser lines is discussed. HCN maser components are spatially resolved for the first time on an astronomical object. We identified two discrete regions in the envelope: a region with a radius of . 15 R*, where molecular species have just formed and the gas has begun to be accelerated (region I) and a shell region (region II) with a radius of 23 R* and a thickness of 15 R*, whose expansion velocity has reached up to 13 km/s, nearly the terminal velocity of 15 km/s. The Si$^{34}$S line detected in region I shows a large expansion velocity of 16 km/s due to strong wing components, indicating that the emission may arise from a shock region in the innermost envelope. In region II, the P.A. of the most copious mass loss direction was found to be 120 +/- 10 degrees, which may correspond to the equatorial direction of the star. Region II contains a torus-like feature. These two regions may have emerged due to significant differences in the size distributions of the dust particles in the two regions.Comment: 26 pages, 8 figures, accepted for publication in The Astrophysical Journal. Please find the pdf at http://www.submm.caltech.edu/~hs/astroph/0904.0280.pdf and the ps file at http://www.submm.caltech.edu/~hs/astroph/0904.0280.p