Rediscovery of Gasteranthusextinctus L.E.Skog & L.P.Kvist (Gesneriaceae) at multiple sites in western Ecuador.

We report the rediscovery of the Critically Endangered cloud forest herb Gasteranthusextinctus, not seen since 1985. In 2019 and 2021, G.extinctus was recorded at five sites in the western foothills of the Ecuadorian Andes, 4-25 km from the type locality at the celebrated Centinela ridge. We describe the species' distribution, abundance, habitat and conservation status and offer recommendations for further research and conservation efforts focused on G.extinctus and the small, disjunct forest remnants it occupies.

From GenBank to GBIF: Phylogeny-Based Predictive Niche Modeling Tests Accuracy of Taxonomic Identifications in Large Occurrence Data Repositories.

Accuracy of taxonomic identifications is crucial to data quality in online repositories of species occurrence data, such as the Global Biodiversity Information Facility (GBIF), which have accumulated several hundred million records over the past 15 years. These data serve as basis for large scale analyses of macroecological and biogeographic patterns and to document environmental changes over time. However, taxonomic identifications are often unreliable, especially for non-vascular plants and fungi including lichens, which may lack critical revisions of voucher specimens. Due to the scale of the problem, restudy of millions of collections is unrealistic and other strategies are needed. Here we propose to use verified, georeferenced occurrence data of a given species to apply predictive niche modeling that can then be used to evaluate unverified occurrences of that species. Selecting the charismatic lichen fungus, Usnea longissima, as a case study, we used georeferenced occurrence records based on sequenced specimens to model its predicted niche. Our results suggest that the target species is largely restricted to a narrow range of boreal and temperate forest in the Northern Hemisphere and that occurrence records in GBIF from tropical regions and the Southern Hemisphere do not represent this taxon, a prediction tested by comparison with taxonomic revisions of Usnea for these regions. As a novel approach, we employed Principal Component Analysis on the environmental grid data used for predictive modeling to visualize potential ecogeographical barriers for the target species; we found that tropical regions conform a strong barrier, explaining why potential niches in the Southern Hemisphere were not colonized by Usnea longissima and instead by morphologically similar species. This approach is an example of how data from two of the most important biodiversity repositories, GenBank and GBIF, can be effectively combined to remotely address the problem of inaccuracy of taxonomic identifications in occurrence data repositories and to provide a filtering mechanism which can considerably reduce the number of voucher specimens that need critical revision, in this case from 4,672 to about 100.

Heat shock-induced changes in lipid and protein metabolism in the endoplasmic reticulum of barley aleurone layers.

Heat shock in barley aleurone layers induces heat shock protein synthesis and suppresses secretory protein synthesis by selectively destabilizing their mRNAs. In addition, the endoplasmic reticulum (ER) membranes upon which secretory protein mRNAs are translated become vesiculated during heat shock, leading to the hypothesis that ER dissociation and targeted mRNA destabilization are linked mechanistically. Supporting this, ER can be heat adapted, and heat-adapted ER has higher levels of fatty acid saturation in membrane phospholipids which do not vesiculate upon heat shock. Secretory protein mRNAs are also more stable in heat-adapted cells. To understand better heat shock-induced changes in ER membranes, we examined ER membrane proteins and enzymes involved in phosphatidylcholine biosynthesis and phospholipid turnover in heat-shocked aleurone cells. Heat shock significantly increased the activity of phospholipases A2 and D, and shortly thereafter significant but gradual increases in choline kinase and phosphocholine glyceride transferase activities and a sharp increase in phosphorylcholine citidyl transferase activity were observed. Only minor changes were observed in SDS-PAGE analyses of proteins from sonicated ER membranes fractionated on continuous sucrose gradients. Overall, heat shock reduced total lipid in ER membranes relative to protein, and in intact, ultracentrifuged aleurone cells examined by light and electron microscopy the ER band appeared to increase in density. The changes in phospholipid metabolism coupled with the suppression of secretory protein synthesis indicate that in addition to inducing a classic heat shock response, high temperature also induces a classic unfolded protein response in the ER of this secretory cell.

Slow heating of barley aleurone layers to heat-shock temperature preserves heat-shock-sensitive cellular properties.

In barley (Hordeum vulgare L. cv. Himalaya) aleurone layers, heat shock causes the selective suppression of α-amylase synthesis by destabilizing this secretory protein's mRNA. The lamellar stacks of the endoplasmic reticulum (ER), which serve as the site of α-amylase mRNA translation, are dissociated by heat shock, suggesting that heat-shock-induced changes in ER may be important in selectively targeting α-amylase mRNAs for destabilization. We have found that samples maintained at heat-shock temperature (40°C) for 18 h recover the ability to synthesize α-amylase and that the ER membranes in these samples contain membrane phospholipids with enhanced levels of fatty acid saturation. This present study investigated whether gradual warming to 40°C over 3-6 h (ramping) would preserve α-amylase synthesis by permitting ER membrane phospholipid retailoring during the gradual temperature increase. Analyses by sodium dodecyl-sulfate polyacrylamide gel electrophoresis revealed that α-amylase synthesis was markedly increased in ramped samples. Furthermore, northern hybridization analyses and transmission electron microscopy showed that these samples had increased α-amylase mRNA levels and stacks of ER lamellae, respectively. Gas chromatographic analyses of ER membrane phospholipids indicated that the fatty acids of ramped samples were more saturated than their heat-shocked counterparts. These data indicate that heat-induced increases in aleurone ER membrane phospholipid fatty acid saturation may be important in maintaining secretory protein expression at normally nonpermissive heat-shock temperatures.