Temporal genetic population structure and interannual variation in migration behavior of Pacific Lamprey <Emphasis Type="Italic">Entosphenus tridentatus</Emphasis>

In this contribution, we review our knowledge on bet-hedging strategies associated with rotifer diapause. First, we describe the ecological scenario under which bet hedging is likely to have evolved in three diapause-related traits in monogonont rotifer populations: (1) the timing of sex (because diapausing eggs are produced via sexual reproduction), (2) the sexual reproduction ratio (i.e. the fraction of sexually reproducing females) and (3) the timing of diapausing egg hatching. Then, we describe how to discriminate among bet-hedging modes and discuss which modes and mechanisms better fit the variability observed in these traits in rotifers. Finally, we evaluate the strength of the empirical evidence for bet hedging in the scarce studies available, and we call for the need of research at different levels of biological complexity to fully understand bet hedging in rotifer diapause.     

Determination of retinol and retinyl esters in human plasma by high-performance liquid chromatography with automated column switching and ultraviolet detection

A HPLC method with automated column switching and UV detection is described for the simultaneous determination of retinol and major retinyl esters (retinyl palmitate, retinyl stearate, retinyl oleate and retinyl linoleate) in human plasma. Plasma (0.2 ml) was deproteinized by adding ethanol (1.5 ml) containing the internal standard retinyl propionate. Following centrifugation the supernatant was directly injected onto the pre-column packed with LiChrospher 100 RP-18 using 1.2% ammonium acetate–acetic acid–ethanol (80:1:20, v/v) as mobile phase. The elution strength of the ethanol containing sample solution was reduced by on-line supply of 1% ammonium acetate–acetic acid–ethanol (100:2:4, v/v). The retained retinol and retinyl esters were then transferred to the analytical column (Superspher 100 RP-18, endcapped) in the backflush mode and chromatographed under isocratic conditions using acetonitrile–methanol–ethanol–2-propanol (1:1:1:1, v/v) as mobile phase. Compounds of interest were detected at 325 nm. The method was linear in the range 2.5–2000 ng/ml with a limit of quantification for retinol and retinyl esters of 2.5 ng/ml. Mean recoveries from plasma were 93.4–96.5% for retinol (range 100–1000 ng/ml) and 92.7–96.0% for retinyl palmitate (range 5–1000 ng/ml). Inter-assay precision was ≤5.1% and ≤6.3% for retinol and retinyl palmitate, respectively. The method was successfully applied to more than 2000 human plasma samples from clinical studies. Endogenous levels of retinol and retinyl esters determined in female volunteers were in good accordance with published data.     

Biparatopic sybodies neutralize SARS‐CoV‐2 variants of concern and mitigate drug resistance

The ongoing COVID‐19 pandemic represents an unprecedented global health crisis. Here, we report the identification of a synthetic nanobody (sybody) pair, Sb#15 and Sb#68, that can bind simultaneously to the SARS‐CoV‐2 spike RBD and efficiently neutralize pseudotyped and live viruses by interfering with ACE2 interaction. Cryo‐EM confirms that Sb#15 and Sb#68 engage two spatially discrete epitopes, influencing rational design of bispecific and tri‐bispecific fusion constructs that exhibit up to 100‐ and 1,000‐fold increase in neutralization potency, respectively. Cryo‐EM of the sybody‐spike complex additionally reveals a novel up‐out RBD conformation. While resistant viruses emerge rapidly in the presence of single binders, no escape variants are observed in the presence of the bispecific sybody. The multivalent bispecific constructs further increase the neutralization potency against globally circulating SARS‐CoV‐2 variants of concern. Our study illustrates the power of multivalency and biparatopic nanobody fusions for the potential development of therapeutic strategies that mitigate the emergence of new SARS‐CoV‐2 escape mutants.     

Ink and Vinegar, a Simple Staining Technique for Arbuscular-Mycorrhizal Fungi

We developed a reliable, inexpensive, and simple method for staining arbuscular-mycorrhizal fungal colonizations in root tissues. Apart from applications in research, this nontoxic, high-quality staining method also could be of great utility in teaching exercises. After adequate clearing with KOH, an ink-vinegar solution successfully stained all fungal structures, rendering them clearly visible.     

Properties of erythrocyte catalase from homozygotes and heterozygotes for Swiss-type acatalasemia

The unstable catalase variant found in the blood of individuals homozygous for Swiss-type acatalasemia and the enzyme species present in heterozygous carriers of this rare defect have been further characterized. The mutant enzyme isolated from acatalasemic red cells is considerably more heat labile and differs in electrophoretic mobility from the normal enzyme. Catalase preparations obtained from heterozygotes consist of an apparently uniform enzyme species, probably representing a molecular hybrid, with properties intermediate to those of the normal and the variant enzyme. However, antigenic identity of catalase from all three sources is observed. Model experiments indicate that hybrid catalase molecules can be produced by recombining normal and variant dimer subunits. Fractionation of erythrocytes according to density and age shows that most of the residual catalase activity is localized in juvenile acatalasemic cells, whereas in normal and heterozygous individuals the catalase activity level does not alter significantly during the life span of the red cells. These findings agree with the observation that there is no gene dosage in heterozygotes, their catalase activity values falling within the normal range.     

Failure of renal denervation to attenuate hypertension in Dahl NaCl-sensitive rats

In previous experiments we have demonstrated that the renal nerves play a significant role in all genetic and (or) induced models of hypertension that we have studied. The current experiments extended this research by investigating the contribution of the renal nerves to hypertension in the Dahl NaCl-sensitive rat. This was investigated by assessing the effect of bilateral phenol renal denervation carried out prior to initiation of a high NaCl (8% NaCl) diet. In two separate studies, renal denervation did not affect systolic blood pressure in either Dahl NaCl-sensitive rats or their normotensive counterparts, Dahl NaCl-resistant rats. Further, denervation did not increase absolute urinary sodium excretion, percent urinary sodium excretion, urinary volume output, or food or water intake; nor did it differentially alter creatinine clearance or body weight. Denervation was verified at the termination of each study by a greater than 80% depletion of renal noradrenaline stores. These results indicate that the renal nerves do not provide a major contribution to hypertension in the Dahl NaCl-sensitive rat.