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This study presents new field and petrological observations combined with geochemical data on a range of komatiitic to tholeiitic volcanic rocks from the ca. 3.48 Ga mid-lower Komati Formation type-section of the Barberton Greenstone Belt, South Africa. A range of mafic-ultramafic rocks is identified across a 1.44 km profile, leading to the proposition of a new preliminary volcanic architecture for the mid-lower Komati Formation type-section. Major, trace and rare earth element (REE) data in conjunction with Lu-Hf isotopic constraints indicate that the tholeiites, newly recognized highmagnesium basalts, basaltic komatiites and komatiites in the volcanic sequence have a primitive mantle signature with no geochemical affinity to Archaean or modern-day supra-subduction zone boninites. The whole rock initial εHf values of spinifex and massive komatiite flows in the lowermost part of the Komati type-section are negative, ranging between -1.9 and -3.1, whereas the second overlying spinifex and massive flow unit records positive initial εHf values between +0.5 and +4.7. A new geodynamic model involving crustal contamination of the mafic-ultramafic lavas is proposed for the Barberton mid-lower Komati Formation type-section, involving mantle plume-crust interaction. The new observations and data indicate that the komatiites erupted as a result of a mantle plume from a hot (>1 600oC) mid-Archaean mantle, in which the earliest volcanic flows were variably affected by crustal contamination during their ascent and eruption. The possibility of incorporation of lower crustal material and/or recycled crust residing in the mantle source region cannot be excluded. This indicates that modern-style plate tectonic processes, such as subduction, may not have been a requirement for the formation of the 3.48 Ga Barberton komatiite suite, with implications for the hydration state, geodynamic processes and secular thermal evolution of the Archaean mantle. [ABSTRACT FROM AUTHOR]

Background: A lack or dysfunction of the anchoring protein laminin‐332 in the basement membrane leads to the skin blistering disorder junctional epidermolysis bullosa (JEB). The mutation c.628G>A in the gene LAMB3 encoding the laminin β3‐chain is associated with generalized intermediate JEB; it may introduce an amino acid substitution (p.Glu210Lys) or disrupt splicing. Objective: This retrospective study aimed at determining the effects of aberrant splicing on the JEB phenotype. Methods: LAMB3 transcription was analysed in two siblings compound heterozygous for the LAMB3 mutations p.Glu210Lys and p.Arg635* with a diverging JEB phenotype from late childhood on. Laminin‐332 levels in skin sections and in cultured keratinocytes were investigated by immunofluorescence staining. Real‐time PCR was used to quantify LAMB3 expression in keratinocytes. RNA splice variants were identified by subcloning of a LAMB3 cDNA fraction and subsequent DNA sequencing. Structural models of laminin‐332 helped to assess the impact of certain mutations on laminin‐332 folding. Results: Both siblings showed diminished LAMB3 expression. Laminin‐332 was equally reduced in skin sections obtained during infancy but differed in keratinocytes isolated during adolescence. Although aberrant LAMB3 splicing with 26 variants was detected in both patients, splicing differed significantly: the full‐length LAMB3 transcript harbouring the p.Glu210Lys mutation was found more often in the patient affected less severely (14/108 vs. 5/106 clones; P = 0.03). Structural modelling predicted that several deletions in LAMB3, but not the point mutation p.Glu210Lys, have an effect on laminin‐332 folding and secretion. Conclusions: Differential LAMB3 mRNA splicing in the patients may explain the disparate JEB phenotype. By elucidating the regulation of laminin‐332 gene expression, these findings may contribute to the development of therapeutic strategies for JEB and might help to understand phenotype modification by splice‐site mutations in other hereditary diseases. Linked Commentary: D.F. Murrell et al. J Eur Acad Dermatol Venereol 2020; 34: 1879–1880. https://doi.org/10.1111/jdv.16859 [ABSTRACT FROM AUTHOR]

Transient response to nivolumab and relapse after infliximab in a patient with primary cutaneous CD8-positive aggressive epidermotropic cytotoxic T-cell lymphoma Dear Editor, Primary cutaneous CD8 SP + sp aggressive epidermotropic T-cell lymphoma (CD8 SP + sp AECTCL) is a very rare subtype of cutaneous T-cell lymphoma. More recent studies evaluated the safety and efficacy of anti-PD-1 antibodies in patients with cutaneous T-cell lymphomas, including a phase Ib study for nivolumab that included 13 cases of mycosis fungoides and five cases of peripheral T-cell lymphoma. [Extracted from the article]

The Archean sub-seafloor has been proposed as an environment for the emergence of life, with septate clusters of titanite microtextures in pillow lava rims argued to be the earliest traces of microbial microboring. Here we use nanoscale secondary ion mass spectrometry (NanoSIMS) to test possible geochemical traces of life in ca. 3.45 Ga pillow lavas of the Barberton Greenstone Belt, South Africa. Sulfi de inclusions in the titanite microtextures record strongly negative sulfur isotope fractionations of δ34SVCDT --39.8‰ to --3.2‰ (VCDT--Vienna Canyon Diablo Troilite). These represent the largest range and most negative δ34S values so far reported from the Archean, and are consistent with an early biogenic origin for the sulfi des. Extensive in situ elemental mapping did not find any organic linings associated with the microtextures, despite the high spatial resolution and sensitivity of the NanoSIMS. The absence of organic linings thus excludes a key line of evidence previously used to support the biogenicity of the microtextures. In contrast, in situ sulfur isotope analysis of basalt-hosted sulfi des provides an alternative approach to investigating the existence and nature of an Archean subseafl oor biosphere. [ABSTRACT FROM AUTHOR]