DNA Extraction from small blood volumes and the processing of cellulose blood cards for use in polymerase chain reaction

This article describes two procedures for the purification of genomic DNA from small blood volumes of whole blood using DNAzol^®BD. In the first procedure, DNA is isolated from 1–20 μL of whole blood using a fast and simple protocol that is appropriate for the simultaneous extraction of a large number of samples. The isolated DNA is suitable for gel electrophoresis and polymerase chain reaction (PCR). In the second procedure, cellulose blood cards containing approx 5 μL of dried blood are treated with DNAzol BD in order to retain DNA on the cellulose matrix while removing other cellular components. The blood card with DNA subsequently serves as template in PCR. The blood card processing and amplification procedures are performed in the same PCR tube without any centrifugation steps, making the combined procedures amenable for automated DNA preparation and amplification in a single tube.     

Tnfaip2/exoc3‐driven lipid metabolism is essential for stem cell differentiation and organ homeostasis

Lipid metabolism influences stem cell maintenance and differentiation but genetic factors that control these processes remain to be delineated. Here, we identify Tnfaip2 as an inhibitor of reprogramming of mouse fibroblasts into induced pluripotent stem cells. Tnfaip2 knockout impairs differentiation of embryonic stem cells (ESCs), and knockdown of the planarian para‐ortholog, Smed‐exoc3, abrogates in vivo tissue homeostasis and regeneration—processes that are driven by somatic stem cells. When stimulated to differentiate, Tnfaip2‐deficient ESCs fail to induce synthesis of cellular triacylglycerol (TAG) and lipid droplets (LD) coinciding with reduced expression of vimentin (Vim)—a known inducer of LD formation. Smed‐exoc3 depletion also causes a strong reduction of TAGs in planarians. The study shows that Tnfaip2 acts epistatically with and upstream of Vim in impairing cellular reprogramming. Supplementing palmitic acid (PA) and palmitoyl‐L‐carnitine (the mobilized form of PA) restores the differentiation capacity of Tnfaip2‐deficient ESCs and organ maintenance in Smed‐exoc3‐depleted planarians. Together, these results identify a novel role of Tnfaip2 and exoc3 in controlling lipid metabolism, which is essential for ESC differentiation and planarian organ maintenance.     

Geographic patterns in seasonal changes of body mass,skull, and brain size of common shrews

1. Some small mammals exhibit Dehnel''s Phenomenon, a drastic decrease in body mass, braincase, and brain size from summer to winter, followed by a regrowth in spring. This is accompanied by a re‐organization of the brain and changes in other organs. The evolutionary link between these changes and seasonality remains unclear, although the intensity of change varies between locations as the phenomenon is thought to lead to energy savings during winter.
2. Here we explored geographic variation of the intensity of Dehnel''s Phenomenon in Sorex araneus. We compiled literature on seasonal changes in braincase size, brain, and body mass, supplemented by our own data from Poland, Germany, and Czech Republic.
3. We analyzed the effect of geographic and climate variables on the intensity of change and patterns of brain re‐organization.
4. From summer to winter, the braincase height decreased by 13%, followed by 10% regrowth in spring. For body mass, the changes were −21%/+82%, respectively. Changes increased toward northeast. Several climate variables were correlated with these transformations, confirming a link of the intensity of the changes with environmental conditions. This relationship differed for the decrease versus regrowth, suggesting that they may have evolved under different selective pressures.
5. We found no geographic trends explaining variability in the brain mass changes although they were similar (−21%/+10%) to those of the braincase size. Underlying patterns of change in brain organization in northeastern Poland were almost identical to the pattern observed in southern Germany. This indicates that local habitat characteristics may play a more important role in determining brain structure than broad scale geographic conditions.
6. We discuss the techniques and criteria used for studying this phenomenon, as well as its potential presence in other taxa and the importance of distinguishing it from other kinds of seasonal variation.

     

A Panicum-derived chromosomal segment captured by Hordeum a few million years ago preserves a set of stress-related genes

Intra-specific variability is a cornerstone of evolutionary success of species. Acquiring genetic material from distant sources is an important adaptive mechanism in bacteria, but it can also play a role in eukaryotes. In this paper, we investigate the nature and evolution of a chromosomal segment of panicoid (Poaceae, Panicoideae) origin occurring in the nuclear genomes of species of the barley genus Hordeum (Pooideae). The segment, spanning over 440 kb in the Asian Hordeum bogdanii and 219 kb in the South American Hordeum pubiflorum, resides on a pair of nucleolar organizer region (NOR)-bearing chromosomes. Conserved synteny and micro-collinearity of the segment in both species indicate a common origin of the segment, which was acquired before the split of the respective barley lineages 5–1.7 million years ago. A major part of the foreign DNA consists of several approximately 68 kb long repeated blocks containing five stress-related protein-coding genes and transposable elements (TEs). Whereas outside these repeats, the locus was invaded by multiple TEs from the host genome, the repeated blocks are rather intact and appear to be preserved. The protein-coding genes remained partly functional, as indicated by conserved reading frames, a low amount of non-synonymous mutations, and expression of mRNA. A screen across Hordeum species targeting the panicoid protein-coding genes revealed the presence of the genes in all species of the section Stenostachys. In summary, our study shows that grass genomes can contain large genomic segments obtained from distantly related species. These segments usually remain undetected, but they may play an important role in the evolution and adaptation of species.