The Relationship between Temperature and Development in Globodera ellingtonae

A new cyst nematode species, Globodera ellingtonae, was recently described from populations in Oregon and Idaho. This nematode has been shown to reproduce on potato. Because of this nematode’s close relationship to the potato cyst nematodes, G. rostochiensis and G. pallida, an understanding of the risk of its potential spread, including prediction of potential geographical distribution, is required. To determine the development of G. ellingtonae under different temperatures, we conducted growth chamber experiments over a range of temperatures (10.0°C to 26.5°C) and tracked length of time to various developmental stages, including adult females bearing the next generation of eggs. Both the time to peak population densities of G. ellingtonae life stages and their duration in roots generally increased with decreasing temperature. Regression of growth rate to second-stage (J2) and third-stage (J3) juveniles on temperature yielded different base temperatures: 6.3°C and 4.4°C for J2 and J3, respectively. Setting a base temperature of 6°C allowed calculation of the degree-days (DD6) over which different life stages occurred. The largest population densities of J2 were found in roots between 50 and 200 DD6. Population densities of J3 peaked between 200 and 300 DD6. Adult males were detected in soil starting at 300 to 400 DD6 and remained detectable for approximately 500 DD6. By 784 to 884 DD6, half of the eggs in adult females contained vermiform juveniles. Given the similarity in temperature ranges for successful development between G. ellingtonae and G. rostochiensis, G. ellingtonae populations likely could survive in the same geographic range in which G. rostochiensis now occurs.     

Vesicoureteral reflux and other urinary tract malformations in mice compound heterozygous for Pax2 and Emx2

Congenital anomalies of the kidney and urinary tract (CAKUT) are the most common cause of chronic kidney disease in children. This disease group includes a spectrum of urinary tract defects including vesicoureteral reflux, duplex kidneys and other developmental defects that can be found alone or in combination. To identify new regulators of CAKUT, we tested the genetic cooperativity between several key regulators of urogenital system development in mice. We found a high incidence of urinary tract anomalies in Pax2;Emx2 compound heterozygous mice that are not found in single heterozygous mice. Pax2^+/−;Emx2^+/− mice harbor duplex systems associated with urinary tract obstruction, bifid ureter and a high penetrance of vesicoureteral reflux. Remarkably, most compound heterozygous mice refluxed at low intravesical pressure. Early analysis of Pax2^+/−;Emx2^+/− embryos point to ureter budding defects as the primary cause of urinary tract anomalies. We additionally establish Pax2 as a direct regulator of Emx2 expression in the Wolffian duct. Together, these results identify a haploinsufficient genetic combination resulting in CAKUT-like phenotype, including a high sensitivity to vesicoureteral reflux. As both genes are located on human chromosome 10q, which is lost in a proportion of VUR patients, these findings may help understand VUR and CAKUT in humans.     

Eph receptors and their ligands: Promising molecular biomarkers and therapeutic targets in prostate cancer

Although at present, there is a high incidence of prostate cancer, particularly in the Western world, mortality from this disease is declining and occurs primarily only from clinically significant late stage tumors with a poor prognosis. A major current focus of this field is the identification of new biomarkers which can detect earlier, and more effectively, clinically significant tumors from those deemed “low risk”, as well as predict the prognostic course of a particular cancer. This strategy can in turn offer novel avenues for targeted therapies. The large family of Receptor Tyrosine Kinases, the Ephs, and their binding partners, the ephrins, has been implicated in many cancers of epithelial origin through stimulation of oncogenic transformation, tumor angiogenesis, and promotion of increased cell survival, invasion and migration. They also show promise as both biomarkers of diagnostic and prognostic value and as targeted therapies in cancer. This review will briefly discuss the complex roles and biological mechanisms of action of these receptors and ligands and, with regard to prostate cancer, highlight their potential as biomarkers for both diagnosis and prognosis, their application as imaging agents, and current approaches to assessing them as therapeutic targets. This review demonstrates the need for future studies into those particular family members that will prove helpful in understanding the biology and potential as targets for treatment of prostate cancer.     

Strong seasonal differences of bacterial polysaccharide utilization in the North Sea over an annual cycle

Marine heterotrophic bacteria contribute considerably to global carbon cycling, in part by utilizing phytoplankton-derived polysaccharides. The patterns and rates of two different polysaccharide utilization modes – extracellular hydrolysis and selfish uptake – have previously been found to change during spring phytoplankton bloom events. Here we investigated seasonal changes in bacterial utilization of three polysaccharides, laminarin, xylan and chondroitin sulfate. Strong seasonal differences were apparent in mode and speed of polysaccharide utilization, as well as in bacterial community compositions. Compared to the winter month of February, during the spring bloom in May, polysaccharide utilization was detected earlier in the incubations and a higher portion of all bacteria took up laminarin selfishly. Highest polysaccharide utilization was measured in June and September, mediated by bacterial communities that were significantly different from spring assemblages. Extensive selfish laminarin uptake, for example, was detectible within a few hours in June, while extracellular hydrolysis of chondroitin was dominant in September. In addition to the well-known Bacteroidota and Gammaproteobacteria clades, the numerically minor verrucomicrobial clade Pedosphaeraceae could be identified as a rapid laminarin utilizer. In summary, polysaccharide utilization proved highly variable over the seasons, both in mode and speed, and also by the bacterial clades involved.     

Lead resistance and sensitivity in Staphylococcus aureus

Abstract Five lead-resistant strains of Staphylococcus aureus were isolated. Plasmid-free lead-sensitive variants were obtained from the three plasmid-bearing strains. Lead-resistant strains tolerated an approximately 600 × higher Pb(NO₃)₂ concentration than lead-sensitive strains. Both types of strains initially bound lead, but only the resistant strains accumulated the metal as an intracellular lead-phosphate.     

A perforin‐like protein mediates disruption of the erythrocyte membrane during egress of Plasmodium berghei male gametocytes

Successful gametogenesis of the malaria parasite depends on egress of the gametocytes from the erythrocytes within which they developed. Egress entails rupture of both the parasitophorous vacuole membrane and the erythrocyte plasma membrane, and precedes the formation of the motile flagellated male gametes in a process called exflagellation. We show here that egress of the male gametocyte depends on the function of a perforin‐like protein, PPLP2. A mutant of Plasmodium berghei lacking PPLP2 displayed abnormal exflagellation; instead of each male gametocyte forming eight flagellated gametes, it produced gametocytes with only one, shared thicker flagellum. Using immunofluorescence and transmission electron microscopy analysis, and phenotype rescue with saponin or a pore‐forming toxin, we conclude that rupture of the erythrocyte membraneis blocked in the mutant. The parasitophorous vacuole membrane, on the other hand, is ruptured normally. Some mutant parasites are still able to develop in the mosquito, possibly because the vigorous motility of the flagellated gametes eventually leads to escape from the persisting erythrocyte membrane. This is the first example of a perforin‐like protein in Plasmodium parasites having a role in egress from the host cell and the first parasite protein shown to be specifically required for erythrocyte membrane disruption during egress.     

Fish intake reflects on DHA level in breast milk among lactating women in Latvia

Background

Docosahexaenoic acid (DHA) is an essential fatty acid required for proper growth and development. DHA levels in breast milk vary worldwide. Higher levels are observed among coastal populations and are associated with marine food consumption. Latvia is located in Northern Europe, on the eastern shore of the Baltic Sea. Nevertheless, fish consumption among women of reproductive age is low. The aim of this study was to determine DHA levels in breast milk among lactating women in Latvia.

Methods

Invitation to participate in the study was posted on a social media member group for breastfeeding mothers. In total, 71 women were enrolled from November 2016 until December 2017. DHA levels (% of total fatty acids) in breast milk were measured by gas chromatography. Information about food consumed during the three consecutive days prior to the milk sampling was obtained and a food frequency questionnaire (FFQ) was completed. Information about maternal and infant characteristics, current breastfeeding pattern and milk expression method was also collected.

Results

The mean age of participants was 31?±?4 years and the mean BMI was 22.1?±?3.2. 27 participants were primiparas. The average age and birth weight for infants (34 males, 33 females) was 6?±?4 months and 3.46?±?0.55 kg, respectively. The median DHA level in breast milk (n?=?60) was 0.30?±?0.18% of total fatty acids and it was not influenced by any of the maternal or infant’s characteristics nor current breastfeeding pattern or milk expression manner (p?>?0.05). Fish intake was a positive predictor for DHA levels in breast milk (r?=?0.318, p?=?0.013). Average maternal DHA intake was 136?±?26, 137?±?33 and 178?±?49 (SEM – standard error of the mean) mg, for the third, second and last day prior to sampling day, respectively.

Conclusions

DHA levels in breast milk among lactating women in Latvia correspond to the suggested target DHA value in breast milk (0.30%). Fish consumption is a significant positive predictor for DHA levels in breast milk, however, daily DHA intake among the participants was lower than recommended (200 mg).

     

Keys to Lipid Selection in Fatty Acid Amide Hydrolase Catalysis: Structural Flexibility,Gating Residues and Multiple Binding Pockets

The fatty acid amide hydrolase (FAAH) regulates the endocannabinoid system cleaving primarily the lipid messenger anandamide. FAAH has been well characterized over the years and, importantly, it represents a promising drug target to treat several diseases, including inflammatory-related diseases and cancer. But its enzymatic mechanism for lipid selection to specifically hydrolyze anandamide, rather than similar bioactive lipids, remains elusive. Here, we clarify this mechanism in FAAH, examining the role of the dynamic paddle, which is formed by the gating residues Phe432 and Trp531 at the boundary between two cavities that form the FAAH catalytic site (the “membrane-access” and the “acyl chain-binding” pockets). We integrate microsecond-long MD simulations of wild type and double mutant model systems (Phe432Ala and Trp531Ala) of FAAH, embedded in a realistic membrane/water environment, with mutagenesis and kinetic experiments. We comparatively analyze three fatty acid substrates with different hydrolysis rates (anandamide > oleamide > palmitoylethanolamide). Our findings identify FAAH’s mechanism to selectively accommodate anandamide into a multi-pocket binding site, and to properly orient the substrate in pre-reactive conformations for efficient hydrolysis that is interceded by the dynamic paddle. Our findings therefore endorse a structural framework for a lipid selection mechanism mediated by structural flexibility and gating residues between multiple binding cavities, as found in FAAH. Based on the available structural data, this exquisite catalytic strategy for substrate specificity seems to be shared by other lipid-degrading enzymes with similar enzymatic architecture. The mechanistic insights for lipid selection might assist de-novo enzyme design or drug discovery efforts.