Time-response and dose-response to acetazolamide in the WB/ReJ and C57BL/6J mouse strains: genetic interaction in the ectrodactyly response

The WB/ReJ and C57BL/6J strains were compared in their time and dose responses to acetazolamide administered in a single subcutaneous injection regime. WB/ReJ has a genetically determined, high-frequency, transient fetal edema that has maximum expression on day 14 and is resolved by day 18. Acetazolamide, at 1,000 mg/kg, appears to induce edema in WB/ReJ with a time of response on days 9 and 10, and the induced edema follows the same time course of appearance and disappearance as the spontaneous trait. The dose-response analysis is not interpretable in the WB/ReJ and C57BL/6J strains and their reciprocal F1 fetuses because there was significant response only at the highest dose (2,000 mg/kg) used in this study. The time of ectrodactyly response is maximal on day 9 in both WB/ReJ and C57BL/6J strains. The dose-response analysis demonstrates that, for the usual measure of total fetuses with ectrodactyly (or penetrance), the Wb/ReJ and C57BL/6J strains and the WB/ReJ x C57BL/6J F1 (WB.B6F1) have the same slope of the dose-response curve and the strain difference in response can be interpreted as a difference in dosage tolerance. The tolerance of WB/ReJ is twofold greater than that of C57BL/6J. This overdominance of relative resistance to acetazolamide ectrodactyly supports the general finding of directional dominance of relative resistance among genetically different strain pairs. The median effective dose for penetrance of the ectrodactyly response of the reciprocal B6.WBF1 embryo is similar to the WB.B6F1, but the slope of the dose-response curve is significantly different, and a different teratogenic mechanism of response may be involved. Ectrodactyly was predominantly right sided in all genotypes, and, in bilaterally affected fetuses, the right forelimb was more severely affected. An unexpected difference between WB/ReJ and C57BL/6J was found when the laterality of ectrodactyly was analyzed further. There is a significant increase with dosage in bilaterally affected fetuses (a measure of expressivity) in C57BL/6J but not in WB/ReJ, even though the dose-response of total affected fetuses (penetrance) is similar in both strains. In C57BL/6J, the left and right forelimbs are correlated in their responses with the left, requiring approximately a threefold greater dose. The left and right forelimbs are symmetrical in response, and the difference can be interpreted in terms of a developmental (or teratogenic) gradient. In WB/ReJ, the right forelimb has the same dose response as C57BL/6J and requires a twofold greater dose than the right forelimb of C57BL/6J, but the left forelimb has a very flat slope and is not correlated with the response of the right.(ABSTRACT TRUNCATED AT 400 WORDS)     

Genetic variability of purine nucleoside phosphorylase activity in the mouse: Relationship to Np-1 and Np-2

A survey of 37 inbred strains for erythrocyte purine nucleoside phosphorylase activity showed a greater than threefold range. Six of these strains had significantly greater activity than the others, and all of the high-activity strains had the Np-2 electrophoretic band. The high-purine nucleoside phosphorylase activity trait corresponding to Np-2 was inherited in an autosomal codominant manner and minor differences were apparent in thermal and kinetic properties between low- and high-activity strains. This work provides further support for there being either two structural loci for purine nucleoside phosphorylase, Np-1 and Np-2, or a regulatory-modifier locus.     

Segregation distortion of X-linked marker genes in interspecific crosses between Mus musculus and M. spretus

An interspecific cross was made between females of the C3H/HeHa.Pgk-1 a inbred laboratory strain of Mus musculus and males of the separate species Mus spretus. The F1 males are sterile but the F1 females are fertile and they were backcrossed to both C3H and spretus males. Evidence is presented from the segregation of X-linked marker genes that the interspecific F1 female has a genetically deleterious effect on the C3H X chromosome that is expressed as a male-lethal effect with the spretus Y chromosome but not with the musculus Y chromosome of C3H.     

Prokaryote populations of extant microbialites along a depth gradient in Pavilion Lake,British Columbia,Canada

Pavilion Lake in British Columbia, Canada, is home to modern‐day microbialites that are actively growing at multiple depths within the lake. While microbialite morphology changes with depth and previous isotopic investigations suggested a biological role in the formation of these carbonate structures, little is known about their microbial communities. Microbialite samples acquired through the Pavilion Lake Research Project (PLRP) were first investigated for phototrophic populations using Cyanobacteria‐specific primers and 16S rRNA gene cloning. These data were expounded on by high‐throughput tagged sequencing analyses of the general bacteria population. These molecular analyses show that the microbial communities of Pavilion Lake microbialites are diverse compared to non‐lithifying microbial mats also found in the lake. Phototrophs and heterotrophs were detected, including species from the recently described Chloroacidobacteria genus, a photoheterotroph that has not been previously observed in microbialite systems. Phototrophs were shown as the most influential contributors to community differences above and below 25 meters, and corresponding shifts in heterotrophic populations were observed at this interface as well. The isotopic composition of carbonate also mirrored this shift in community states. Comparisons to previous studies indicated this population shift may be a consequence of changes in lake chemistry at this depth. Microbial community composition did not correlate with changing microbialite morphology with depth, suggesting something other than community changes may be a key to observed variations in microbialite structure.     

Rebuild the Academy: Supporting academic mothers during COVID-19 and beyond

The issues facing academic mothers have been discussed for decades. Coronavirus Disease 2019 (COVID-19) is further exposing these inequalities as womxn scientists who are parenting while also engaging in a combination of academic related duties are falling behind. These inequities can be solved by investing strategically in solutions. Here we describe strategies that would ensure a more equitable academy for working mothers now and in the future. While the data are clear that mothers are being disproportionately impacted by COVID-19, many groups could benefit from these strategies. Rather than rebuilding what we once knew, let us be the architects of a new world.

The COVID-19 pandemic is highlighting the many long-standing inequalities that academic mothers face. This Essay describes solutions for a more equitable academia, now and in the future, maintaining that rather than rebuilding what we once knew, we should be the architects of a new world.     

Archaea of the Miscellaneous Crenarchaeotal Group are abundant,diverse and widespread in marine sediments

Members of the highly diverse Miscellaneous Crenarchaeotal Group (MCG) are globally distributed in various marine and continental habitats. In this study, we applied a polyphasic approach (rRNA slot blot hybridization, quantitative PCR (qPCR) and catalyzed reporter deposition FISH) using newly developed probes and primers for the in situ detection and quantification of MCG crenarchaeota in diverse types of marine sediments and microbial mats. In general, abundance of MCG (cocci, 0.4 μm) relative to other archaea was highest (12–100%) in anoxic, low-energy environments characterized by deeper sulfate depletion and lower microbial respiration rates (P=0.06 for slot blot and P=0.05 for qPCR). When studied in high depth resolution in the White Oak River estuary and Hydrate Ridge methane seeps, changes in MCG abundance relative to total archaea and MCG phylogenetic composition did not correlate with changes in sulfate reduction or methane oxidation with depth. In addition, MCG abundance did not vary significantly (P>0.1) between seep sites (with high rates of methanotrophy) and non-seep sites (with low rates of methanotrophy). This suggests that MCG are likely not methanotrophs. MCG crenarchaeota are highly diverse and contain 17 subgroups, with a range of intragroup similarity of 82 to 94%. This high diversity and widespread distribution in subsurface sediments indicates that this group is globally important in sedimentary processes.     

Horizontal gene transfer and the rock record: comparative genomics of phylogenetically distant bacteria that induce wrinkle structure formation in modern sediments

Wrinkle structures are sedimentary features that are produced primarily through the trapping and binding of siliciclastic sediments by mat‐forming micro‐organisms. Wrinkle structures and related sedimentary structures in the rock record are commonly interpreted to represent the stabilizing influence of cyanobacteria on sediments because cyanobacteria are known to produce similar textures and structures in modern tidal flat settings. However, other extant bacteria such as filamentous representatives of the family Beggiatoaceae can also interact with sediments to produce sedimentary features that morphologically resemble many of those associated with cyanobacteria‐dominated mats. While Beggiatoa spp. and cyanobacteria are metabolically and phylogenetically distant, genomic analyses show that the two groups share hundreds of homologous genes, likely as the result of horizontal gene transfer. The comparative genomics results described here suggest that some horizontally transferred genes may code for phenotypic traits such as filament formation, chemotaxis, and the production of extracellular polymeric substances that potentially underlie the similar biostabilizing influences of these organisms on sediments. We suggest that the ecological utility of certain basic life modes such as the construction of mats and biofilms, coupled with the lateral mobility of genes in the microbial world, introduces an element of uncertainty into the inference of specific phylogenetic origins from gross morphological features preserved in the ancient rock record.