Prostaglandins or prostaglandin like substances are implicated in normal growth and development in oomycetes

The prostaglandin synthesis inhibitors aspirin and indomethacin inhibit the growth of Achlya caroliniana, A. ambisexualis and Saprolegnia parasitica in a dose-related manner. In addition, the inhibitors cause the formation of a characteristic asterisk-shaped colony. This abnormal colony morphology does not appear to be dependent on medium composition, since three different nitrogen and five differentcarbon sources all support the abnormal growth in the presence of 0.1 mM indomethacin. The abnormal colony morphology is the result of abnormal branching. Inhibitor grown colonies are more densely branched than controls, with shorter distances between branches. Inhibited colonies allowed to grow for greater than ten days escape the inhibition and assume a normal gross colony morphology and size, however, they do not reproduce sexually. The addition of 2 micrograms/ml PGF1 alpha to the growth medium partially overcomes the growth inhibition caused by indomethacin. The data suggest a role for prostaglandin or prostaglandin-like compounds in oomycete development.     

Body proportions,microhabitat selection,and adaptive radiation of Liolaemus lizards in central Chile

Summary A biometric analysis of body proportions with presumably functional meaning for microhabitat selection was made on 12 species of Liolaemus lizards in central Chile. Characters studied were forelimb length, hindlimb length, tail length (all standardized by the corresponding snout-vent length), and the ratio forelimb/hindlimb length. It is shown that irrespective of terrestrial, saxicolous, or arboreal habits, Liolaemus species are remarkably similar in body proportions. The only exceptions are: L. lemniscatus, an open ground-dweller which exhibits significantly shorter limbs; and L. chiliensis and L. schroederi, both shrub-climbers which exhibit significantly longer tail. It is concluded that the adaptive radiation of Liolaemus lizards in central Chile has been accomplished mainly by diversification of activity time, food size, and microhabitat type. Morphological divergence in body proportions seems to have played an unimportant role.     

Stomatal density and aperture length in four plant species grown across a subambient CO2 gradient

Stomatal density, stomatal aperture length, area/leaf, and number of stomata/leaf were measured after the annual C₃ agronomic grasses oats (Avena sativa) and wheat (Triticum aestivum), the C, woody legume honey mesquite (Prosopis glandulosa), and the perennial C₄ grass little bluestem (Schizachyrium scoparium) were grown across a subambient carbon dioxide concentration ([CO₂]) gradient from near 200 to 350 μmol/mol in a growth chamber. The purpose was to determine if the size and density of stomata vary in response to atmospheric [CO₂] during growth, across a subambient [CO₂] range representative of the doubling that has occurred since the last ice age. Changes in stomatal density and aperture length with increasing [CO₂] were small when detected. Stomatal density decreased on adaxial flag leaf surfaces of wheat, and aperture length increased slightly with [CO₂], Leaf area and number of stomata/flag leaf increased by similar proportions with [CO₂] in two wheat cultivars. No consistent relationship between [CO₂] and stomatal density or size was detected in mesquite, oats, or little bluestem. We conclude that individual plants of these species lack the plasticity to significantly alter stomatal density and aperture length in response to increasing atmospheric [CO₂] in a single generation (annuals) or growing season (perennials).     

Measurement of cellular DNA mass by flow microfluorometry with use of a biological internal standard

Use of a biological standard (chicken erythrocytes) mixed with experimental cell populations allows control of all variables in flow microfluorometric determination of DNA content. These variables include both staining and instrument procedures. In addition, the use of a biological standard allows determination of cellular DNA mass in unperturbed cell populations. DNA mass measured by FMF technique correlates closely with values reported in the literature that used biochemical techniques.     

Empirical patterns of environmental variation favor adaptive transgenerational plasticity

Effects of parental environment on offspring traits have been well known for decades. Interest in this transgenerational form of phenotypic plasticity has recently surged due to advances in our understanding of its mechanistic basis. Theoretical research has simultaneously advanced by predicting the environmental conditions that should favor the adaptive evolution of transgenerational plasticity. Yet whether such conditions actually exist in nature remains largely unexplored. Here, using long‐term climate data, we modeled optimal levels of transgenerational plasticity for an organism with a one‐year life cycle at a spatial resolution of 4 km² across the continental United States. Both annual temperature and precipitation levels were often autocorrelated, but the strength and direction of these autocorrelations varied considerably even among nearby sites. When present, such environmental autocorrelations render offspring environments statistically predictable based on the parental environment, a key condition for the adaptive evolution of transgenerational plasticity. Results of our optimality models were consistent with this prediction: High levels of transgenerational plasticity were favored at sites with strong environmental autocorrelations, and little‐to‐no transgenerational plasticity was favored at sites with weak or nonexistent autocorrelations. These results are among the first to show that natural patterns of environmental variation favor the evolution of adaptive transgenerational plasticity. Furthermore, these findings suggest that transgenerational plasticity is likely variable in nature, depending on site‐specific patterns of environmental variation.     

History of safe exposure and bioinformatic assessment of phosphomannose-isomerase (PMI) for allergenic risk

Newly expressed proteins in genetically engineered crops are evaluated for potential cross reactivity to known allergens as part of their safety assessment. This assessment uses a weight-of-evidence approach. Two key components of this allergenicity assessment include any history of safe human exposure to the protein and/or the source organism from which it was originally derived, and bioinformatic analysis identifying amino acid sequence relatedness to known allergens. Phosphomannose-isomerase (PMI) has been expressed in commercialized genetically engineered (GE) crops as a selectable marker since 2010 with no known reports of allergy, which supports a history of safe exposure, and GE events expressing the PMI protein have been approved globally based on expert safety analysis. Bioinformatic analyses identified an eight-amino-acid contiguous match between PMI and a frog parvalbumin allergen (CAC83047.1). While short amino acid matches have been shown to be a poor predictor of allergen cross reactivity, most regulatory bodies require such matches be assessed in support of the allergenicity risk assessment. Here, this match is shown to be of negligible risk of conferring cross reactivity with known allergens.