Maternal weight affects placental DNA methylation of genes involved in metabolic pathways in the common marmoset monkey (Callithrix jacchus)

Accumulating evidence suggests that dysregulation of placental DNA methylation (DNAm) is a mechanism linking maternal weight during pregnancy to metabolic programming outcomes. The common marmoset, Callithrix jaccus, is a platyrrhine primate species that has provided much insight into studies of the primate placenta, maternal condition, and metabolic programming, yet the relationships between maternal weight and placental DNAm are unknown. Here, we report genome-wide DNAm from term marmoset placentas using reduced representation bisulfite sequencing. We identified 74 genes whose DNAm pattern is associated with maternal weight during gestation. These genes are predominantly involved in energy metabolism and homeostasis, including the regulation of glycolytic and lipid metabolic processes pathways.     

Reassessment of the status of Lymantria albescens and Lymantria postalba (Lepidoptera: Erebidae: Lymantriinae) as distinct ‘Asian gypsy moth’ species,using both mitochondrial and nuclear sequence data

For regulatory purposes, the name ‘Asian gypsy moth’ refers to a group of closely related Asian Lymantria species and subspecies whose female moths display flight capability, a trait believed to confer enhanced invasiveness relative to the European gypsy moth, Lymantria dispar dispar, whose females are flightless. Lymantria albescens and Lymantria postalba are Asian gypsy moths occurring in the southern Ryukyu Islands and in the northern Ryukyu and adjacent Kyushu and Shikoku Islands of Japan, respectively. Although once considered subspecies of L. dispar, their status as distinct species, relative to the latter, is now well established. While postalba was subsequently considered a subspecies of L. albescens, largely on the basis of differences in forewing ground colour in males, both taxa were later given distinct species status by Pogue & Schaefer (2007) following their revision of the genus Lymantria. Here, we re-examined the validity of this revised status through the sequencing of a large portion of the mitochondrial genome (c. 60%) and multiple nuclear marker genes [elongation factor 1-alpha (Ef-1α), wingless (Wgl), internal transcribed spacer 2 (ITS-2), ribosomal protein S5 (RpS5)] in representative specimens of both taxa and other Lymantria species, including L. monacha, L. xylina, L. mathura and members of the L. dispar + L. umbrosa clade. A comparison of the number of substitutions in these genomic regions among the taxa we considered showed lower or equivalent variation between L. albescens and L. postalba compared with subspecies of L. dispar, for mitochondrial and nuclear sequences, respectively. This finding was reflected in the maximum likelihood trees generated independently for mitochondrial and nuclear data, where L. albescens and L. postalba formed, in both analyses, a short-branch sister clade basal to the L. dispar + L. umbrosa clade. We further sequenced three markers [cytochrome c oxydase 1 (COI), EF-1α, Wgl] in multiple L. albescens–L. postalba specimens collected along a south-to-north transect across the Ryukyu Arc and observed no clear distinction among the sampled specimens as a function of taxonomic designation. We conclude that L. albescens and L. postalba form a single species, with postalba representing a darker-winged morph along an apparent south-to-north wing colour cline. Accordingly, L. postalba is relegated to synonymy under L. albescens ( syn.n. ).     

A cross-continental test of the Enemy Release Hypothesis: leaf herbivory on Acer platanoides (L.) is three times lower in North America than in its native Europe

Acer platanoides (Norway maple) is a widespread native tree species in Europe. It has been introduced to North America where it has often established dense stands in both secondary woodlands and relatively undisturbed mature woodlands. In Europe A. platanoides is also extending its original range, but generally seems to exist at much lower densities. One explanation for the ‘aggressiveness’ of invasive plants such as A. platanoides is that they have left behind pests and diseases which limit their population densities in their native lands (the enemy release hypothesis or ERH). To assess the ERH for Norway maple, a large network of collaborators assessed leaf herbivory rates in populations throughout Europe and North America. We found significantly lower total leaf herbivory (1.6% ± 0.19, n = 21 vs. 7.4% ± 1.94, n = 34) and lower fungal damage (1.0% ± 0.35, n = 13 vs. 3.7% ± 0.85, n = 34) in North America than in Europe over a 2 year period, which is consistent with the predictions of the Enemy Release Hypothesis. Across years, the average total leaf herbivory was significantly correlated with average annual temperature of the site (P < 0.05), although this was mostly due to sites in Europe (P < 0.001), and not sites in North America (P > 0.05). Furthermore, only populations in Europe showed very high levels of herbivory (e.g., nine sites had total leaf herbivory ranging from 10.0 to 51.2% in at least 1 year) or leaf fungal damage (only one site in North America showed high levels of fungal damage in 1 year), suggesting the possibility of more frequent episodic outbreaks in the native range. Leaf herbivory and fungal damage are only two aspects of consumer pressure and we do not know whether the differences reported here are enough to actually elicit release from top-down population control, but such large scale biogeographic differences in herbivory contribute towards understanding exotic invasions. Jonathan M. Adams and Wei Fang—equally contributed as first authors. A list of the participating members of the Transatlantic Acer platanoides Invasion Network is given in the Appendix 3.     

Phylogenetic analysis of actinobacterial populations associated with Antarctic Dry Valley mineral soils

Despite the apparent severity of the environmental conditions in the McMurdo Dry Valleys, Eastern Antarctica, recent phylogenetic studies conducted on mineral soil samples have revealed the presence of a wide diversity of microorganisms, with actinobacteria representing one of the largest phylotypic groups. Previous metagenomic studies have shown that the majority of Antarctic actinobacterial populations are classified as 'uncultured'. In this study, we assessed the diversity of actinobacteria in Antarctic cold desert soils by complementing traditional culture-based techniques with a metagenomic study. Phylogenetic analysis of clones generated with actinobacterium- and streptomycete-specific PCR primers revealed that the majority of the phylotypes were most closely related to uncultured Pseudonocardia and Nocardioides species. Phylotypes most closely related to a number of rarer actinobacteria genera, including Geodermatophilus , Modestobacter and Sporichthya , were also identified. While complementary culture-dependent studies isolated a number of Nocardia and Pseudonocardia species, the majority of the cultured isolates (> 80%) were S treptomyces species – although phylotypes affiliated to the genus Streptomyces were detected at a low frequency in the metagenomic study. This study confirms that Antarctic Dry Valley desert soil harbours highly diverse actinobacterial communities and suggests that many of the phylotypes identified may represent novel, uncultured species.     

The Effect of Maillard Conjugation of Deamidated Wheat Proteins with Low Molecular Weight Carbohydrates on the Secondary Structure of the Protein

A soluble isolated wheat protein fraction (sIWP) prepared from isolated wheat protein (30–35% deamidation) was incubated alone or in the presence of glucose or maltodextrins of various molecular weights (MW 1, 1.9 and 4.3 kDa) at 60 °C and 75% relative humidity to promote the formation of Maillard conjugates. The formation of Maillard conjugates was confirmed by the loss of available -NH₂ groups on incubation. Approximately 3–4 carbohydrate moieties (glucose or low molecular weight carbohydrates in the commercial maltodextrin) were attached per mole of sIWP after 24 h incubation. Principal component analysis of attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectra measured in the dry state showed that there were no major structural changes among non-incubated sIWP, sIWP incubated alone, sIWP–glucose conjugate and sIWP–maltodextrin (MW 1 kDa) conjugate. Structural changes were observed when the protein was incubated with larger molecular weight maltodextrin (MW 1.9 kDa or 4.3 kDa). However, there were no detectable differences in their circular dichroism (CD) spectra suggesting the absence of conformational changes in proteins with or without attached carbohydrates in solution state. The differences between the FTIR and CD results are possibly due to differences in water content of the samples although pressure-induced changes to protein structure induced in the ATR cell and the influence of unreacted maltodextrins cannot be discounted. Attachment of low molecular weight carbohydrate moieties on a relatively large molecular weight protein (i.e. sIWP with average MW of 40.4 kDa) with low lysine content (average three per mole of protein) is not sufficient to have an impact on the secondary structure of the protein.     

TMEM41B and VMP1 are scramblases and regulate the distribution of cholesterol and phosphatidylserine

TMEM41B and VMP1 are integral membrane proteins of the endoplasmic reticulum (ER) and regulate the formation of autophagosomes, lipid droplets (LDs), and lipoproteins. Recently, TMEM41B was identified as a crucial host factor for infection by all coronaviruses and flaviviruses. The molecular function of TMEM41B and VMP1, which belong to a large evolutionarily conserved family, remains elusive. Here, we show that TMEM41B and VMP1 are phospholipid scramblases whose deficiency impairs the normal cellular distribution of cholesterol and phosphatidylserine. Their mechanism of action on LD formation is likely to be different from that of seipin. Their role in maintaining cellular phosphatidylserine and cholesterol homeostasis may partially explain their requirement for viral infection. Our results suggest that the proper sorting and distribution of cellular lipids are essential for organelle biogenesis and viral infection.     

Thermal adaptations to extreme freeze–thaw cycles in the high tropical Andes

Temperature plays a key role in the biology of ectotherms, including anurans, which are found at higher elevations in the tropics than anywhere in the temperate zone. High elevation tropical environments are characterized by extreme daily thermal fluctuation including high daily maxima and nightly freezing. Our study investigated the contrasting operative temperatures of the anurans Telmatobius marmoratus and Pleurodema marmoratum in different environmental contexts at the same elevation and biome above 5,200 m. Telmatobius marmoratus avoids extremes of daily temperature fluctuation by utilizing thermally buffered aquatic habitat at all life stages, with minimal operative temperature variation (range: 4.6–8.0°C). Pleurodema marmoratum, in contrast, experienced operative temperatures from ?3.5 to 44°C and has one of the widest thermal breadths reported for any tropical frog, from >32°C (critical thermal maximum) to surviving freezing periods of 1 and 6 hr down to ?3.0°C. Our findings expand experimental evidence of frost tolerance in amphibians to the widespread Neotropical family Leptodactylidae, the first such evidence of frost tolerance in a tropical amphibian. Our study identifies three strategies (wide thermal tolerance breadth, use of buffered microhabitats, and behavioral thermoregulation), which allow these tropical frogs to withstand the current wide daily thermal fluctuation above 5,000 m.a.s.l. and which may help them adapt to future climatic changes. Abstract in Spanish is available with online material