Regenerative proliferation of differentiated cells by mTORC1‐dependent paligenosis

In 1900, Adami speculated that a sequence of context‐independent energetic and structural changes governed the reversion of differentiated cells to a proliferative, regenerative state. Accordingly, we show here that differentiated cells in diverse organs become proliferative via a shared program. Metaplasia‐inducing injury caused both gastric chief and pancreatic acinar cells to decrease mTORC1 activity and massively upregulate lysosomes/autophagosomes; then increase damage associated metaplastic genes such as Sox9; and finally reactivate mTORC1 and re‐enter the cell cycle. Blocking mTORC1 permitted autophagy and metaplastic gene induction but blocked cell cycle re‐entry at S‐phase. In kidney and liver regeneration and in human gastric metaplasia, mTORC1 also correlated with proliferation. In lysosome‐defective Gnptab^?/? mice, both metaplasia‐associated gene expression changes and mTORC1‐mediated proliferation were deficient in pancreas and stomach. Our findings indicate differentiated cells become proliferative using a sequential program with intervening checkpoints: (i) differentiated cell structure degradation; (ii) metaplasia‐ or progenitor‐associated gene induction; (iii) cell cycle re‐entry. We propose this program, which we term “paligenosis”, is a fundamental process, like apoptosis, available to differentiated cells to fuel regeneration following injury.     

Field test of an automated radio‐telemetry system: tracking local space use of aerial insectivores

Documenting local space use of birds that move rapidly, but are too small to carry GPS tags, such as swallows and swifts, can be challenging. For these species, tracking methods such as manual radio‐telemetry and visual observation are either inadequate or labor‐ and time‐intensive. Another option is use of an automated telemetry system, but equipment for such systems can be costly when many receivers are used. Our objective, therefore, was to determine if an automated radio‐telemetry system, consisting of just two receivers, could provide an alternative to manual tracking for gathering data on local space use of six individuals of three species of aerial insectivores, including one Cliff Swallow (Petrochelidon pyrrhonota), one Eastern Phoebe (Sayornis phoebe), and four Barn Swallows (Hirundo rustica). We established automated radio‐telemetry systems at three sites near the city of Peterborough in eastern Ontario, Canada, from May to August 2015. We evaluated the location error of our two‐receiver system using data from moving and stationary test transmitters at known locations, and used telemetry data from the aerial insectivores as a test of the system's ability to track rapidly moving birds under field conditions. Median location error was ~250 m for automated telemetry test locations after filtering. More than 90% of estimated locations had large location errors and were removed from analysis, including all locations > 1 km from receiver stations. Our automated telemetry receivers recorded 17,634 detections of the six radio‐tagged birds. However, filtering removed an average of 89% of bird location estimates, leaving only the Cliff Swallow with enough locations for analysis of space use. Our results demonstrate that a minimal automated radio‐telemetry system can be used to assess local space use by small, highly mobile birds, but the resolution of the data collected using only two receiver stations was coarse and had a limited range. To improve both location accuracy and increase the percentage of usable location estimates collected, we suggest that, in future studies, investigators use receivers that simultaneously record signals detected by all antennas, and use of a minimum of three receiver stations with more antennas at each station.     

Aberrant DNA Methylation: Implications in Racial Health Disparity

BackgroundIncidence and mortality rates of colorectal carcinoma (CRC) are higher in African Americans (AAs) than in Caucasian Americans (CAs). Deficient micronutrient intake due to dietary restrictions in racial/ethnic populations can alter genetic and molecular profiles leading to dysregulated methylation patterns and the inheritance of somatic to germline mutations.ResultsDNA from the tumor of AA CRC patients, compared to adjacent normal tissues, contained 1,588 hypermethylated and 100 hypomethylated differentially methylated regions (DMRs). Whereas, 109 hypermethylated and 4 hypomethylated DMRs were observed in DNA from the tumor of CA CRC patients; representing a 14.6-fold and 25-fold change, respectively. Specifically; CHL1, 4 anti-inflammatory genes (i.e., NELL1, GDF1, ARHGEF4, and ITGA4), and 7 miRNAs (of which miR-9-3p and miR-124-3p have been implicated in CRC) were hypermethylated in DNA samples from AA patients with CRC. From the same sample set, RNAseq analysis revealed 108 downregulated genes (including 14 ribosomal proteins) and 34 upregulated genes (including POLR2B and CYP1B1 [targets of miR-124-3p]) in AA patients with CRC versus CA patients.ConclusionDNA methylation profile and/or products of its downstream targets could serve as biomarker(s) addressing racial health disparity.     

Chemical Polymorphism of Origanum compactum Grown in All Natural Habitats in Morocco

Origanum compactum L. (Lamiaceae) is one of the most important medicinal species in term of ethnobotany in Morocco. It is considered as a very threatened species as it is heavily exploited. Its domestication remains the most efficient way to safeguard it for future generations. For this purpose, wide evaluation of the existing variability in all over the Moroccan territory is required. The essential oils of 527 individual plants belonging to 88 populations collected from the whole distribution area of the species in Morocco were analyzed by GC/MS. The dominant constituents were carvacrol (0 – 96.3%), thymol (0 – 80.7%), p‐cymene (0.2 – 58.6%), γ‐terpinene (0 – 35.2%), carvacryl methyl ether (0 – 36.2%), and α‐terpineol (0 – 25.8%). While in the Middle Atlas region and the Central Morocco mainly carvacrol type samples were found, much higher chemotypic diversity was encountered within samples from the north part of Morocco (occidental and central Rif regions). The high chemical polymorphism of plants offers a wide range for selection of valuable chemotypes, as a part of breeding and domestication programs of this threatened species.     

Active and adaptive Legionella CRISPR‐Cas reveals a recurrent challenge to the pathogen

Clustered regularly interspaced short palindromic repeats with CRISPR‐associated gene (CRISPR‐Cas) systems are widely recognized as critical genome defense systems that protect microbes from external threats such as bacteriophage infection. Several isolates of the intracellular pathogen Legionella pneumophila possess multiple CRISPR‐Cas systems (type I‐C, type I‐F and type II‐B), yet the targets of these systems remain unknown. With the recent observation that at least one of these systems (II‐B) plays a non‐canonical role in supporting intracellular replication, the possibility remained that these systems are vestigial genome defense systems co‐opted for other purposes. Our data indicate that this is not the case. Using an established plasmid transformation assay, we demonstrate that type I‐C, I‐F and II‐B CRISPR‐Cas provide protection against spacer targets. We observe efficient laboratory acquisition of new spacers under ‘priming’ conditions, in which initially incomplete target elimination leads to the generation of new spacers and ultimate loss of the invasive DNA. Critically, we identify the first known target of L. pneumophila CRISPR‐Cas: a 30 kb episome of unknown function whose interbacterial transfer is guarded against by CRISPR‐Cas. We provide evidence that the element can subvert CRISPR‐Cas by mutating its targeted sequences – but that primed spacer acquisition may limit this mechanism of escape. Rather than generally impinging on bacterial fitness, this element drives a host specialization event – with improved fitness in Acanthamoeba but a reduced ability to replicate in other hosts and conditions. These observations add to a growing body of evidence that host range restriction can serve as an existential threat to L. pneumophila in the wild.     

Calcium dependence of C-type natriuretic peptide-formed fast K+ channel

The lipid bilayertechnique was used to characterize theCa²⁺ dependence of a fastK⁺ channel formed by a synthetic17-amino acid segment [OaCNP-39-(1-17)] ofa 39-amino acid C-type natriuretic peptide (OaCNP-39) found in platypus (Ornithorhynchusanatinus) venom (OaV). TheOaCNP-39-(1-17)-formed K⁺ channel was reversiblydependent on1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid-buffered cis (cytoplasmic)Ca²⁺ concentration([Ca²⁺]_cis).The channel was fully active when[Ca²⁺]_ciswas >10⁴ M andtrans (luminal)Ca²⁺ concentration was 1.0 mM, butnot at low[Ca²⁺]_cis.The open probability of single channels increased from zero at1 × 10⁶ McisCa²⁺ to 0.73 ± 0.17 (n = 22) at10³ McisCa²⁺. Channel openings to themaximum conductance of 38 pS were rapidly and reversibly activated when[Ca²⁺]_cis,but not transCa²⁺ concentration(n = 5), was increased to >5 × 10⁴ M(n = 14). Channel openings to thesubmaximal conductance of 10.5 pS were dominant at5 × 10⁴ MCa²⁺.K⁺ channels did not open whencisMg²⁺ orSr²⁺ concentrations were increasedfrom zero to 10³ M or when[Ca²⁺]_ciswas maintained at 10⁶ M(n = 3 and 2). The Hill coefficientand the inhibition constant were 1 and 0.8 × 10⁴ McisCa²⁺, respectively. Thisdependence of the channel on high[Ca²⁺]_cissuggests that it may become active under1) physiological conditions whereCa²⁺ levels are high, e.g., duringcardiac and skeletal muscle contractions, and2) pathological conditions that leadto a Ca²⁺ overload, e.g., ischemicheart and muscle fatigue. The channel could modify a cascade ofphysiological functions that are dependent on theCa²⁺-activatedK⁺ channels, e.g., vasodilationand salt secretion.

     

Microsatellite DNA analysis of spatial and temporal population structuring of <Emphasis Type="Italic">Phragmites australis</Emphasis> along the Hudson River Estuary

Phragmites australis is a perennial grass that has invaded wetlands of the northeastern United States over the past century. The Hudson River Estuary and surrounding watersheds are no exception in that populations of P. australis have spread dramatically along its shores and tributaries in the past 40 years. Recent studies have shown that genetically variable populations of P. australis can spread by seed dispersal in addition to clonal mechanisms. It is important to characterize the genetic variation of Hudson River populations as part of a management strategy for this species to determine the mechanisms by which its spreads and colonizes new habitats, particularly those with frequent anthropogenic disturbances. The goals of this study were to quantify levels of genetic variation and structuring in Hudson River populations of P. australis using microsatellite DNA analysis. A total of 354 culms of P. australis were collected from nine locations ranging from Albany, New York to Staten Island, New York in the summers of 2004 (N = 174) and 2011 (N = 180). Microsatellite data from eight loci indicated that the Hudson River Estuary has some of the highest levels of genetic variation of all U. S. Atlantic Coast regions containing P. australis. Gene diversity (Hs) across all loci in the 2004 collection was 0.45 (±0.02) and that of the 2011 collection was 0.47 (±0.07). Patches within sample sites were rarely monoclonal and had multiple genetic phenotypes. Moran’s Identity tests indicated that individuals within a patch were closely related, whereas little genetic relatedness was evident among individuals from sample sites >1 km apart. Spatial structuring was also not evident in autospatial correlation and principle coordinate analyses. These findings suggest that genetic diversity is maintained within stands by sexual reproduction and that seeds are important in dispersal of P. australis across the Hudson River Estuary. Ample habitats are available for establishment of new Phragmites stands due to high levels of anthropogenic disturbance from populations living along the Estuary. Wildlife managers should focus on monitoring habitats that provide seedbed for Phragmites and promote land use practices that prevent soil disturbance and establishment of new stands.