Anastomosis is required for virulence of the fungal necrotroph Alternaria brassicicola

A fungal mycelium is typically composed of radially extending hyphal filaments interconnected by bridges created through anastomoses. These bridges facilitate the dissemination of nutrients, water, and signaling molecules throughout the colony. In this study, we used targeted gene deletion and nitrate utilization mutants of the cruciferous pathogen Alternaria brassicicola and two closely related species to investigate hyphal fusion (anastomosis) and its role in the ability of fungi to cause disease. All eight of the A. brassicicola isolates tested, as well as A. mimicula and A. japonica, were capable of self-fusion, with two isolates of A. brassicicola being capable of non-self-fusion. Disruption of the anastomosis gene homolog (Aso1) in A. brassicicola resulted in both the loss of self-anastomosis and pathogenicity on cabbage. This finding, combined with our discovery that a previously described nonpathogenic A. brassicicola mutant defective for a mitogen-activated protein kinase gene (amk1) also lacked the capacity for self-anastomosis, suggests that self-anastomosis is associated with pathogenicity in A. brassicicola.     

Orientation to solar radiation in black wildebeest (<Emphasis Type="Italic">Connochaetes gnou</Emphasis>)

We recorded the body axis orientation of free-living black wildebeest relative to incident solar radiation and wind. Observations were made on three consecutive days, on six occasions over the course of 1 year, in a treeless, predominantly cloudless habitat. Frequency of orientation parallel to incident solar radiation increased, and perpendicular to incident solar radiation decreased, as ambient dry-bulb temperature or solar radiation intensity increased, or wind speed decreased. We believe these changes were mediated via their effect on skin temperature. Parallel orientation behavior was more prominent when the wildebeest were standing without feeding than it was when they were feeding. We calculate that a black wildebeest adopting parallel orientation throughout the diurnal period would absorb 30% less radiant heat than the same animal adopting perpendicular orientation. Parallel orientation was reduced at times when water was freely available, possibly reflecting a shift from behavioral to autonomic thermoregulatory mechanisms. The use of orientation behavior by black wildebeest is well developed and forms part of the suite of adaptations that help them to maintain heat balance while living in a shadeless, often hot, environment.     

Production of rhamnolipids in solid-state cultivation using a mixture of sugarcane bagasse and corn bran supplemented with glycerol and soybean oil

Rhamnolipid biosurfactants are attracting attention due to their low toxicity, high biodegradability, and good ecological acceptability. However, production in submerged culture is made difficult by severe foaming problems. Solid-state cultivation (SSC) is a promising alternative production method. In the current work, we report the optimization of rhamnolipid production by Pseudomonas aeruginosa UFPEDA 614 on a solid substrate containing sugarcane bagasse and corn bran. The best rhamnolipid production, 45 g/l of impregnating solution used, was obtained with a 50:50 (m/m) mixture of sugarcane bagasse and corn bran supplemented with an impregnating solution containing 6% (v/v) of each of glycerol and soybean oil. This level is comparable with those of previous studies undertaken in solid-state cultivation; the composition of the biosurfactant is similar, but our medium is cheaper. Our work therefore provides a suitable basis for future studies of the development of an SSC-based process for rhamnolipid production.     

Twenty-year outcome analysis of genetic screening programs for Tay-Sachs and beta-thalassemia disease carriers in high schools.

Programs for education, screening, and counseling of senior-high-school students, in populations at high risk for Tay-Sachs and beta-thalassemia diseases, have existed for >20 years in Montreal. Four process and outcome variables are reported here: (i) voluntary participation rates in the high-school cohort; (ii) uptake rates for the screening test; (iii) origin of carrier couples seeking the prenatal diagnosis option in the programs; and (iv) change in incidence of the two diseases. Between 1972 and 1992, we screened 14,844 Ashkenazi-Jewish students, identified 521 HexA-deficient carriers (frequency 1:28), reached 89% of the demographic cohort in the educational component of the program, and achieved 67% voluntary participation in the subsequent screening phase. The corresponding data for the beta-thalassemia program are 25,274 students (mainly of Mediterranean origin) representing 67% of the cohort with 61% voluntary participation in the screening phase (693 carriers; frequency 1:36). From demographic data, we deduce that virtually all the carriers identified in the high-school screening program remembered their status, had their partner tested if they did not already know they were a carrier couple, and took up the options for reproductive counseling/prenatal diagnosis. In Montreal, the current origin of all couples using prenatal diagnosis for Tay-Sachs and beta-thalassemia diseases is the corresponding genetic screening/testing program, whereas, at the beginning of the programs, it was always because there was a history of an affected person in the family. Incidence of the two diseases has fallen by 90%-95% over 20 years; the rare new cases are born (with two exceptions) outside the target communities or to nonscreened couples.     

Bottom-up approaches in synthetic biology and biomaterials for tissue engineering applications

Synthetic biologists use engineering principles to design and construct genetic circuits for programming cells with novel functions. A bottom-up approach is commonly used to design and construct genetic circuits by piecing together functional modules that are capable of reprogramming cells with novel behavior. While genetic circuits control cell operations through the tight regulation of gene expression, a diverse array of environmental factors within the extracellular space also has a significant impact on cell behavior. This extracellular space offers an addition route for synthetic biologists to apply their engineering principles to program cell-responsive modules within the extracellular space using biomaterials. In this review, we discuss how taking a bottom-up approach to build genetic circuits using DNA modules can be applied to biomaterials for controlling cell behavior from the extracellular milieu. We suggest that, by collectively controlling intrinsic and extrinsic signals in synthetic biology and biomaterials, tissue engineering outcomes can be improved.     

The binding of asialo-glycoprotein to isolated Golgi apparatus

Membranes of the Golgi apparatus isolated from rat liver were capable of binding ¹²⁵I-asialo-fetuin in a manner similar to the binding to liver plasma membranes. Although the binding capacity of the Golgi membranes was less than that of plasma membranes, binding was dependent on Ca⁺⁺ ions and inhibited by α-lactalbumin in both cases. Specific activities of galactosyl and sialyl transferases were about 20 times greater in Golgi than in plasma membranes isolated from the same livers. This dramatic reciprocal relationship between enzyme levels and binding capacities of the two membranous fractions argues against either of these enzymes being the actual binding site.     

The Revised Classification of Eukaryotes

This revision of the classification of eukaryotes, which updates that of Adl et al. [J. Eukaryot. Microbiol. 52 (2005) 399], retains an emphasis on the protists and incorporates changes since 2005 that have resolved nodes and branches in phylogenetic trees. Whereas the previous revision was successful in re‐introducing name stability to the classification, this revision provides a classification for lineages that were then still unresolved. The supergroups have withstood phylogenetic hypothesis testing with some modifications, but despite some progress, problematic nodes at the base of the eukaryotic tree still remain to be statistically resolved. Looking forward, subsequent transformations to our understanding of the diversity of life will be from the discovery of novel lineages in previously under‐sampled areas and from environmental genomic information.     

Characterization of the active sites in decay-accelerating factor

Decay-accelerating factor (DAF) is a complement regulator that dissociates autologous C3 convertases, which assemble on self cell surfaces. Its activity resides in the last three of its four complement control protein repeats (CCP2-4). Previous modeling on the nuclear magnetic resonance structure of CCP15-16 in the serum C3 convertase regulator factor H proposed a positively charged surface area on CCP2 extending into CCP3, and hydrophobic moieties between CCPs 2 and 3 as being primary convertase-interactive sites. To map the residues providing for the activity of DAF, we analyzed the functions of 31 primarily alanine substitution mutants based in part on this model. Replacing R69, R96, R100, and K127 in the positively charged CCP2-3 groove or hydrophobic F148 and L171 in CCP3 markedly impaired the function of DAF in both activation pathways. Significantly, mutations of K126 and F169 and of R206 and R212 in downstream CCP4 selectively reduced alternative pathway activity without affecting classical pathway activity. Rhesus macaque DAF has all the above human critical residues except for F169, which is an L, and its CCPs exhibited full activity against the human classical pathway C3 convertase. The recombinants whose function was preferentially impaired against the alternative pathway C3bBb compared with the classical pathway C4b2a were tested in classical pathway C5 convertase (C4b2a3b) assays. The effects on C4b2a and C4b2a3b were comparable, indicating that DAF functions similarly on the two enzymes. When CCP2-3 of DAF were oriented according to the crystal structure of CCP1-2 of membrane cofactor protein, the essential residues formed a contiguous region, suggesting a similar spatial relationship.     

Balancing Fairness and Efficiency: The Impact of Identity-Blind and Identity-Conscious Accountability on Applicant Screening

This study compared two forms of accountability that can be used to promote diversity and fairness in personnel selections: identity-conscious accountability (holding decision makers accountable for which groups are selected) versus identity-blind accountability (holding decision makers accountable for making fair selections). In a simulated application screening process, undergraduate participants (majority female) sorted applicants under conditions of identity-conscious accountability, identity-blind accountability, or no accountability for an applicant pool in which white males either did or did not have a human capital advantage. Under identity-conscious accountability, participants exhibited pro-female and pro-minority bias, particularly in the white-male-advantage applicant pool. Under identity-blind accountability, participants exhibited no biases and candidate qualifications dominated interview recommendations. Participants exhibited greater resentment toward management under identity-conscious accountability.