Cell and cell nucleus deformations have been implicated in the mechanotransduction of mechanical loads acting on tissues. While in situ cell nucleus deformation in response to increasing tissue strains has been examined in articular cartilage this phenomenon has not been investigated in tendons. To examine in situ cell nuclei deformation in tendons undergoing tensile strain rat tail tendons were harvested from adult Sprague-Dawley rats and stained with acridine orange to highlight the cell nuclei. The tendons were mounted on a custom-designed, low-load, tensile testing device affixed to the mechanical stage of a confocal laser microscope. Cells within the tendons were isolated for analysis. Images of individual cells were captured at 0'%1 strain as well as sequentially at 2'%,, 4% and 6'%1 gripto-grip tendon strain. Digital images of the cell nuclei were then measured in the s (length) and y (height) axis and deformation expressed as a percentage of cell nuclei strain. In addition, centroid-to-centroid distances of adjacent cell nuclei within each image were measured and used to calculate local tissue strain. There was a weak (r2 = 0.34) but significant (p < 0.01) correlation between local tissue strain and cell nucleus strain in the x axis. The results of this study support the hypothesis that in situ cell nucleus deformation does occur during tensile loading of tendons. This deformation may play a significant role in the mechanical signal transduction pathway of this tissue.

Scanning electron microscopy, confocal scanning laser microscopy, and fatty acid methyl ester profiles were used to study the development, organization, and structure of aerobic multispecies biofilm communities in granular activated-carbon (GAC) fluidized-bed reactors treating petroleum-contaminated groundwaters. The sequential development of biofilm structure was studied in a laboratory reactor fed toluene-amended groundwater and colonized by the indigenous aquifer populations. During the early stages of colonization, microcolonies were observed primarily in crevices and other regions sheltered from hydraulic shear forces. Eventually, these microcolonies grew over the entire surface of the GAC. This growth led to the development of discrete discontinuous multilayer biofilm structures. Cell-free channel-like structures of variable sizes were observed to interconnect the surface film with the deep inner layers. These interconnections appeared to increase the biological surface area per unit volume ratio, which may facilitate transport of substrates into and waste products out of deep regions of the biofilm at rates greater than possible by diffusion alone. These architectural features were also observed in biofilms from four field-scale GAC reactors that were in commercial operation treating petroleum-contaminated groundwaters. These shared features suggest that formation of cell-free channel structures and their maintenance may be a general microbial strategy to deal with the problem of limiting diffusive transport in thick biofilms typical of fluidized-bed reactors.

Farinography and mixography are two commonly used procedures for evaluating dough properties. These procedures, however, cannot separate hydration and energy input during dough development, both of which are critically important for understanding fundamental rheological properties of dough. A rheometer and laser scanning confocal microscopy (LSCM) were used to study the relationship between rheological properties and microstructural characteristics of developed (by farinograph with both shear and extensional deformations), of partially developed (by rheometer with either shear or extensional deformation), and of nondeveloped (no deformation) dough samples of wheat flours. Rheological data revealed that developed dough had the highest G* (most elastic or strong), followed by doughs partially developed with extensional deformation, and then shear deformation, and finally by nondeveloped dough. The LSCM z‐sectioning (scanning of different layers of the sample) and the analysis of amount of protein matrix showed that developed dough had the most protein matrix and nondeveloped dough had the least protein matrix. It also showed that the higher the G*, the greater the protein network. Moreover, the type of deformation appeared to contribute to the development of protein matrix and further increase the dough strength. In this study, a combination of shear and extensional deformations by farinograph produced the most protein matrix and the strongest dough, followed by extensional deformation, shear deformation, and then no deformation.

The genomic relationship between V. darrowi Camp (2n = 2x = 24) and V. corymbosum L. (2n = 4x = 48) was examined using an interspecific tetraploid hybrid, US 75, and representatives of the parental species. Two features in the background of US 75 led to the prediction that it was an allopolyploid: (1) the parental species are quite distinct morphologically and geographically, and (2) the diploid genome was incorporated into US 75 via an unreduced gamete. However, US 75 recently was shown to display tetrasomic inheritance using molecular markers. In the present cytological study, US 75 was found to have a lower than expected number of multivalents for an autopolyploid, although it had a significantly higher number of quadrivalents than its autotetraploid parent, V. corymbosum. Normal chromosome distributions were observed at anaphase I and II, and pollen viability was high. Our findings suggest that little genomic divergence has developed between the Vaccinium species and that the polyploids may freely exchange genes with sympatric diploid species via unreduced gametes. This pattern of hybridization could be an important component of evolution in all autopolyploid groups, making them much more dynamic than traditionally assumed.

Aflatoxins are highly toxic and carcinogenic fungal secondary metabolites. At least 18 enzyme activities are required for aflatoxin biosynthesis in the filamentous fungus Aspergillus parasiticus. One of these enzymes, versicolorin B synthase (VBS), catalyzes bisfuran ring closure in versiconal hemiacetal (a reaction near the middle of the pathway) to form versicolorin B. This reaction is required for the subsequent activation to aflatoxin B1-8,9 epoxide, a highly reactive and toxic aflatoxin metabolite, and is important for aflatoxin toxicity. We analyzed the localization of VBS in the aflatoxin-producing strain A. parasiticus SU-1 grown on solid media using a colony fractionation technique developed previously. A highly specific polyclonal antibody, raised against a maltose-binding protein-VBS fusion protein synthesized in Escherichia coli, was used to detect VBS in SU-1 grown on a rich solid medium via immunofluorescence confocal laser scanning microscopy (CLSM) and immunogold transmission electron microscopy (TEM). VBS was detected in both vegetative hyphae and in asexual developmental structures, called conidiophores. Western blot and CLSM analyses demonstrated the highest abundance of VBS in colony fraction S2 consisting of cells that had grown for 24-48 h; this fraction also contained the highest levels of newly developed conidiophores and the highest abundance of aflatoxin B1, consistent with VBS abundance. At the subcellular level, CLSM and TEM detected VBS distributed throughout the cytoplasm and concentrated in ring-like structures surrounding nuclei. It is uncertain whether enzymatically active VBS is present in either or both locations.

The chromosomal location of T-DNA inserts in ten independently derived and confirmed transgenic plants of P. hybrida was detected by in situ hybridization. Nine transgenic plants had the T-DNA inserts at single sites distributed among each of the seven chromosomes; in one plant the T-DNA inserts were detected on two different chromosomes. Although the T-DNA inserts were integrated randomly among the chromosomes, seven of the 11 total inserts were located at or near the telomere. Thus, T-DNA inserts appear to have potential for tagging chromosomes and chromosome fragments.

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