The reproduction of Gram-negative protoplasts and the influence of environmental conditions on this process

Kanaparthi, Dheeraj; Lampe, Marko; Zhu, Baoli; Klingl, Andreas; Lueders, Tillmann; Schwille, Petra

doi:10.1101/2021.11.25.470037

Cited by 3 publications

(3 citation statements)

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“…Morphological similarity between microfossils from far-flung sites like Western Australia and Southern Africa could be explained by the similarity in the environmental conditions in both sites (5). This relationship between cell morphology, reproductive processes, and environmental conditions was discussed extensively in our previous work (27,65). The experimental conditions that we employed in our study are likely similar to the environmental conditions faced by Archaean organisms from both these sites at the time of their fossilization.…”

Section: Discussionmentioning

confidence: 64%

“…Based on these results, we propose that Archaean microfossils were likely liposome-like cells, which had evolved mechanisms for energy conservation but not for regulating cell morphology and replication. In an earlier study, we have shown that the morphologies of such primitive cells are determined by environmental conditions (27,65) rather than the information encoded in their genome. Given this lack of intrinsic ability to regulate their morphology, we argue that morphological features such as cell size, shape, or cytological complexity are reliable factors in interpreting either the phylogeny or the physiology of microfossils (at least from Archaean Eon).…”

Section: Discussionmentioning

confidence: 97%

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On the nature of the earliest known lifeforms

Kanaparthi

Lampe

Zhu

et al. 2021

Preprint

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Oldest known microfossils were known to have the most complex of morphologies among prokaryotes. Given the morphology of an organism is governed by information encoded in its genome, it was proposed that these primitive organisms most likely possessed complex molecular biological processes. Here we worked with bacterial protoplasts under environmental conditions of Archaean earth and reproduced morphologies of every known microfossil and associated structures. Contrary to the current presumption, our work suggest that complex morphologies of these microfossils could be explained not by presence but by complete absence of molecular biological mechanisms. Environmental conditions and architecture of the cell membrane are the only factors that determined the morphology of these organisms. Based on our observations we present a case for reinterpretation of Archaean microfossils as protocells that were devoid of complex molecular biological processes rather than annotating them to a particular phylogenetic group of extant bacteria.

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Section: Discussionmentioning

confidence: 64%

Section: Discussionmentioning

confidence: 97%

On the nature of the earliest known lifeforms

Kanaparthi

Lampe

Zhu

et al. 2021

Preprint

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“…One key factor that has fostered the attribution of Paleo-and Mesoproterozoic microfossils from Ongeluk formation ( ˜ 2.4 Ga) 17 , Gunflint iron formations ( ˜ 2Ga) 23 , Grassy Bay formation ( ˜ 1Ga) 18 , and Lakhanda formation ( ˜ 1Ga) 19 , is their similarity in size and basic morphology to extant fungi. However, we have previously shown that bacteria could transform into their protoplast state under some environmental conditions [24][25][26] , and cell wall could have evolved no earlier than ~2 Ga (this manuscript is under preparation). Based on these results, we argue that morphology is not a reliable indicator in the identification of fungal microfossils.…”

mentioning

confidence: 98%

On the annotation of Paleo- and Mesoproterozoic microfossils as fungi

Kanaparthi,

Lampe,

Krings

et al. 2024

Preprint

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How old is the crown group Fungi? Inferences from phylogenetic and fossil-based studies provided far-apart age estimates ranging between 0.75 to 2.7 billion years old. One important criterion for interpreting Paleo- and Mesoproterozoic microfossils as Fungi is their uncanny morphological resemblance with extant fungi. Here, we demonstrate that bacteria exposed to environmental conditions similar to the paleoenvironmental settings where these presumed fungi lived can spontaneously transform into their protoplasts. These protoplasts exhibit morphologies corresponding to those of presumed fungal microfossils. These observations, together with microfossil chemical composition, pose a serious challenge to interpreting Paleo- and Mesoproterozoic microfossils as fungi. Based on these results, we reiterate that morphology is not a reliable indicator of the phylogeny of microfossils older than 2.5Ga.

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The reproduction process of Gram-positive protocells

Kanaparthi,

Lampe,

Krohn

et al. 2024

Sci Rep

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Protocells are believed to have existed on early Earth prior to the emergence of prokaryotes. Due to their rudimentary nature, it is widely accepted that these protocells lacked intracellular mechanisms to regulate their reproduction, thereby relying heavily on environmental conditions. To understand protocell reproduction, we adopted a top–down approach of transforming a Gram-positive bacterium into a lipid-vesicle-like state. In this state, cells lacked intrinsic mechanisms to regulate their morphology or reproduction, resembling theoretical propositions on protocells. Subsequently, we grew these proxy-protocells under the environmental conditions of early Earth to understand their impact on protocell reproduction. Despite the lack of molecular biological coordination, cells in our study underwent reproduction in an organized manner. The method and the efficiency of their reproduction can be explained by an interplay between the physicochemical properties of cell constituents and environmental conditions. While the overall reproductive efficiency in these top-down modified cells was lower than their counterparts with a cell wall, the process always resulted in viable daughter cells. Given the simplicity and suitability of this reproduction method to early Earth environmental conditions, we propose that primitive protocells likely reproduced by a process like the one we described below.

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The reproduction of Gram-negative protoplasts and the influence of environmental conditions on this process

Cited by 3 publications

References 109 publications

On the nature of the earliest known lifeforms

On the nature of the earliest known lifeforms

On the annotation of Paleo- and Mesoproterozoic microfossils as fungi

The reproduction process of Gram-positive protocells

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