NanoSIMS Imaging of Bioaccumulation and Subcellular Distribution of Manganese During Oyster Gametogenesis

Abstract

Many bivalve mollusks display remarkable sex differentiation of gonadal accumulation of manganese (Mn), but the underlying processes responsible for such differences have seldom been explored. In this study, the accumulation of Mn in male and female gonads during the reproductive cycle of oysters was first examined, and the distributions of Mn in oocytes and sperm cells at different developmental stages were imaged by the nanoscale secondary ion mass spectrometry (NanoSIMS) at the subcellular level. We found that the distribution and accumulation of Mn during oogenesis were closely associated with the formation and translocation of cortical granules. This is the first time that the enrichment of Mn was directly visualized in cortical granules, which was identified as the major storage site of Mn in oocytes of oysters. Yolk granules were revealed as another storage pool of Mn in oyster oocytes with lower accumulation. In contrast, Mn was mainly distributed in the nucleus of sperm cells with accumulation levels much lower than those in cortical and yolk granules of oocytes. These results demonstrated great differences of the subcellular localization and accumulation capacity of Mn between oocytes and sperm cells in oysters, implying the sex differentiation in susceptibility of reproductive response to Mn stress. Our study also highlights the importance of gender difference in future biomonitoring and ecotoxicological studies of Mn in marine bivalves.

Marine Colloids Boost Nitrogen Fixation in Trichodesmium erythraeum by Photoelectrophy

“…Furthermore, the abundance of Glu (the substrate for Chl a synthesis and the GS−GOGAT cycle) in Fe-limited cells may be significantly increased by MC, as verified by the increases in Chl a and N 2 fixation. NanoSIMS has become one of the most promising techniques for elemental imaging, 59,60 providing direct evidence for carbon and nitrogen assimilation in Trichodesmium. Compared with that in the control, the 12 C 15 N/ 12 C 14 N enrichment in T. erythraeum increased by 29.6 ± 3.23% (p < 0.01) in response to MC, while the accumulation of 56 Fe 16 O/ 12 C increased by 52.0 ± 8.31% (p > 0.05) in cyanobacterial cells treated with MC (Figure 3g−i).…”

Self-Assembled Nanoscale Manganese Oxides Enhance Carbon Capture by Diatoms

“…Combining phytoplankton with nanomaterials into biohybrid systems provides the potential to decrease atmospheric CO 2 levels. , However, the cytotoxicity and high cost of engineered nanomaterials limit the development of sustainable photosynthetic biohybrid systems. For example, most biocompatible materials (e.g., carbon or graphite) exert cyto- and genotoxic effects on stem cells, microorganisms, and even animals. , Engineered manganese-based nanomaterials have also been reported to be genotoxic in bivalve mollusks and plants. − In addition, nanomaterials derived from chemical synthesis often require highly pure reagents, high temperatures, or complex microfabrication techniques. , The development of novel methods to solve these key issues is urgently needed.…”

Contaminação aquática por rejeito de mineração: o caso do desastre ambiental de Mariana (MG)

“…Por fim, uma das características inerente aos metais é a sua não-degradabilidade, que os torna passíveis de acumulação nos ambientes e assimilação nos organismos expostos a estes contaminantes (MERCIAI et al 2015), podendo ser bioacumulados e biomagnificados na cadeia trófica. Muitos estudos já identificaram metais bioacumulados em organismos aquáticos (MUYSSEN & JANSSEN 2002;MIAO et al, 2012;MEMMERT, 1987;RIBEIRO et al, 2017;ARAUJO et al, 2019) inclusive o Mn e o Fe (SEYMORE et al 1995;NORWOOD et al, 2006;KASYAN, 2007;HU et al, 2012;OBERHOLSTER 2012;ALMEIDA et al, 2015;WENG et al, 2021). Apesar de serem metais essenciais, tanto o Mn quanto o Fe são passíveis de bioacumulação em todos os níveis tróficos, além de causarem efeitos nocivos ao indivíduo e consequentemente à população ou comunidade na qual está inserido.…”

“…No entanto, o excesso de Mn pode ser nocivo de diversas formas a fauna aquática. A bioacumulação de Mn em bivalves marinhos afeta o sistema reprodutivo tanto em machos quanto em fêmeas, pois se depositam em grânulos corticais dos oocitos de fêmeas e em núcleos espermáticos de machos (WENG et al 2021). Em caranguejos uma dieta com excesso de Mn evidencia a natureza essencial e tóxica deste metal uma vez que, em baixas quantidades (até 38 mg/kg), ele estimula o crescimento corporal e ganho de biomassa destes organismos, no entanto, em concentrações mais elevadas (acima de 53 mg/kg), acumulam nos músculos, carapaça e no sistema hepatopâncreas além de estimular resposta de genes antioxidantes (HU et al, 2021).…”