Basal Zone Research Articles

Changes in DNA, dry mass and protein content of leaf epidermis nuclei during aging of perennial monocotyledonous plants

DNA, NYS and DNFB protein contents were measured cytophotometrically using the Feulgen method in the nuclei of the epidermis from. the basal zone of young leaves and from the basal and apical zones of old leaves in two perennial monocotyledonous species, <i>Clivia miniata</i> and <i>Rhoeo discolor</i>. Dry mass was determined interferometrically. It was shown that nuclei with a 2C DNA content dominated in both zones of old leaves, and that a significant percentage of cells with a DNA content below 2C were present. The ratio between euchromatin DNA and heterochromatin DNA indicates a greater decrease in euchromatin during aging. Changes in DNA due to real DNA loss are accompanied by decreases in NYS and DNFB stained proteins and a decrease in dry mass content correlated mainly with the decrease in the amount of NYS proteins.

Activation of rape (Brassica napus L.) embryo during seed germination. IV. Germinating embryo. The first zones of mitoses, starch and DNA synthesis and their expansion pattern

The rape radicle is completely covered by the root cap. The successive lateral cell layers of the root cap are terminated by T-forming walls in the dermatogen layer in a statistically constant position. T-walls in dermatogen were utilized for delimitation of successive root sectors on longitudinal microtome sections at the succeeding germination stages. The length and the cell number of the corresponding sectors were studied and the starch and DNA synthesis sites as well as cell divisions localized. All these processes are initiated in a constant sequence and in specific embryo zones. The first symptom of activation of the embryo is starch synthesis. It begins in two centres: in the apical part of the radicle columella and in the hypoctyl dermalogen it moves deep into the cortex and in both directions along the columella the activation of starch synthesis shifts basipetally into the whole columella and the initial centre as well as the lateral parts of the root cap. From the hypocotyl dermatogen it moves into the cortex and in both directions along the embryo axis. In the root dermatogen and periblem the activation zone is first located in the basal sector and, then, gradually, in the lower ones. Just before germination the basal and apical zones of activation meet. Starch can then, be found throughout the root. During starch synthesis, in the basal part of the radicle. DNA synthesis and cell growth begin. In the root sectors which have already begun to grow and synthesize DNA, cell divisions start. The boundary of the dividing cells zone shifts acropetally at some distance above the lower boundary of DNA synthesis and the zone of cell premitotic growth. The acropetal shift of the mitotic activation zones can be described as wave expansion. Before the first mitotic wave reaches the promeristem it is followed by at least three acropetal waves, arising in the already activated basal sectors. and then the mitoses are asynchronised. Mitotic.: activation of the root cap is partly independent of the acropetal wave of cell activation and results from the expanding weaker basipetal wave.

Lichen planus pemphigoides in a child

IntroductionLichen planus pemphigoides (LPP) is a rare autoimmune subepidermal blistering disease characterized by evolution of vesico-bullous skin lesions in patients with active lichen planus. We describe a case of LPP in a 12-year-old girl with clinical, histological and direct immunofluorescence findings. Case reportA 12-year-old Moroccan girl presented, after sun burn, pruritic violaceus papules on hands and feet complicated by the apparition of bullous lesions on apparent normal skin and on lichenoid eruption. A white reticulated pattern was present on the oral mucosa. Histopathology of lichenoid papule and bulla was consistent with the diagnosis of LPP. Direct immunofluorescence of peribullous skin showed linear deposits of IgG and C3 at the basal membrane zone. Treatment with Dapsone was successful. DiscussionLPP is exceptional in children; just fifteen cases were reported in the literature. This condition seems to be idiopathic. However, in rare cases it has been associated with some drugs or after PUVA therapy. In our patient, it was probably induced by prolonged sun exposure.

Activation of rape (Brassica napus L.) embryo during seed germination. V. The first zones of ultrastructural changes and their expansion

In the germinating rape embryo the columella and basal part of hypocotyl undergo earliest activation. Its first ultrastructural symptom is the appearance of numerous ER vesicles after 3-6 h of seed swelling. Their number is the highest in the external layers of the columella and decreases in basipetal direction. Dermatogen cells in the basal zone of the hypocotyl contain the greatest amount of ER structures, whereas decreasing amounts are found in both directions along the embryo axis and centripetally. Further changes in the ER spread in a similar order. The vesicles merge and form a tubular and plate-like ER. Then, they disappear and are replaced by tubular and vesicular forms. The changes in the ER are gradually followed by ultrastructural symptoms of activation of mitochondria, plastids and dictyosomes. The highest number of ER structures and other organelles accumulate in root cells shortly before piercing of the seed coat. After germination their amount decreases and remains almost stable.

The gynoecium structure in Dracaena fragrans (L.) Ker Gawl., Sansevieria parva N.E. Brown and S. trifasciata Prain (Asparagaceae) with special emphasis on the structure of the septal nectary

In the gynoecium of <em>Dracaena fragrans</em>, <em>Sansevieria</em> <em>parva </em>and <em>S. trifasciata</em>, the vertical zonality of the ovary, the structural zonality of the gynoecium following Leinfellner, and the zonality of the septal nectary were studied. The ovary structure is characterised by a high parenchymatous ovary base and ovary roof as well as a long septal nectary that can be extended in both of them and opens with secretory nectary splits. The gynoecium of these species has a short synascidiate zone, a fertile hemisynascidiate zone with a median ovule attached, a hemisymlicate zone (only in <em>D. fragrans</em>) and an asymplicate zone (with postgenitally fused carpels) that comprises the ovary roof, common style and stigma. In the septal nectary, we detected three vertical zones: the basal zone of the distinct nectary in the ovary base or/and the synascidiate zone, the zone of the common nectary (in the hemisynascidiate and hemisymlicate zones) and the zone of the external nectary (the nectary splits in the asymplicate zone). The gynoecium structure in the studied species shows differences in the length of the gynoecium and septal nectary zones and also in the interrelationships of all these three types of vertical zonality.

Mechanism Analysis on Vertical Gradation of Rock Avalanches Triggered by Wenchuan Earthquake, Sichuan, China

Study on rock avalanche kinematics is still a hotspot in the world, especially after the Wenchuan earthquake. To examine this mechanism further, some rock avalanches triggered by the Wenchuan earthquake are taken as objects in this paper. After a detailed field investigation of the vertical profiles revealed by natural longitudinal trenches formed in the rock avalanche deposits, an obvious vertical gradation along their sliding paths is observed, and proposed to be divided into five zones from the top to the bottom and named as follows: the air-blast zone, the bouncing and jumping zone, the sliding and deposit zone, the basal travel zone, and the original accumulation zone. Based on the characteristics of these zones, the formation of each zone is discussed in detail with corresponding conclusions proposed: (1) The air-blast zone, as the upper boundary of the area damaged by rock avalanches, is destroyed by wind gusts initiated by a large rapidly moving mass. (2) The bouncing and jumping zone, mainly characterized by the display of accumulated fine grains and isolated blocks, is produced by the co-work of escaping force of entrapped air and debris internal force. (3) The coupling effect of kinematic sieving and momentum transfer is the main reason for the formation of sliding and deposit zone. (4) Debris in basal travel zone goes through a complex dynamical process: collision, dilation, fragmentation, rotation and sliding, and compaction. In this process, both the overburden pressure and the self-excited vibration energized by the undulated slip surface are the main dynamical forces controlling the formation of basal travel zone. And the simple shear and pure shear modes are the main mechanical behaviors, which realize the formation of particle fragmentation, a binary mixture with coarse particles embedded in clay matrix, and alignment distribution of particles in basal travel zone.

Basal water-bearing zone of the oil-sands deposits of the Cretaceous McMurray Formation at Christina Lake, Alberta, Canada

The Cretaceous McMurray Formation at Christina Lake in Alberta, Canada contains bitumen-rich sand bodies in the lower part. These sand bodies were deposited in lowstand fluvial systems with the onset of relative sea-level rise in the Western Canada foreland basin, forming thick interconnected bodies along the paleovalley. Oil recovery from these reservoirs commonly suffers from bottom water, which reduces not only pay thickness but also the efficiency of thermal recovery processes. For successful oil production in this area, basal water-bearing zone should be investigated and incorporated in determining optimistic well locations and operational strategies. Examination of 455 wireline logs reveals a widespread water-bearing zone at the basal part of the McMurray Formation at Christina Lake. The basal water-bearing zone is relatively thick on paleotopographic lows, particularly along the paleovalley. This result suggests that paleotopography played a crucial role in the distribution of the basal water-bearing zone.

Targeting AMCase reduces esophageal eosinophilic inflammation and remodeling in a mouse model of egg induced eosinophilic esophagitis.

Studies of AMCase inhibition in mouse models of lung eosinophilic inflammation have produced conflicting results with some studies demonstrating inhibition of eosinophilic inflammation and others not. No studies have investigated the role of AMCase inhibition in eosinophilic esophagitis (EoE). We have used a mouse model of egg (OVA) induced EoE to determine whether pharmacologic inhibition of AMCase with allosamidin reduced eosinophilic inflammation and remodeling in the esophagus in EoE. Administration of intra-esophageal OVA for 6weeks to BALB/c mice induced increased levels of esophageal eosinophils, mast cells, and features of esophageal remodeling (fibrosis, basal zone hyperplasia, deposition of the extracellular matrix protein fibronectin). Administration of intraperitoneal (ip) allosamidin to BALB/c mice significantly inhibited AMCase enzymatic activity in the esophagus. Pharmacologic inhibition of AMCase with ip allosamidin inhibited both OVA induced increases in esophageal eosinophilic inflammation and OVA induced esophageal remodeling (fibrosis, epithelial basal zone hyperplasia, extracellular matrix deposition of fibronectin). This inhibition of eosinophilic inflammation in the esophagus by ip allosamidin was associated with reduced eotaxin-1 expression in the esophagus. Oral allosamidin inhibited eosinophilic inflammation in the epithelium but did not inhibit esophageal remodeling. These studies suggest that pharmacologic inhibition of AMCase results in inhibition of eosinophilic inflammation and remodeling in the esophagus in a mouse model of egg induced EoE partially through effects in the esophagus on reducing chemokines (i.e. eotaxin-1) implicated in the pathogenesis of EoE.

Sessile Serrated Adenomas: An Evidence-Based Guide to Management

The concept of serrated colorectal neoplasia and a serrated pathway to colorectal cancer (CRC) is relatively new and continuing to evolve, but it has become highly relevant to gastroenterologists, pathologist, and oncologists alike. Sessile serrated adenomas (SSA) are now thought to be the major precursor lesion of serrated pathway cancers, which represent up to one-third of all sporadic CRC cases. However, despite their increasingly recognized importance, relatively little is known about the epidemiology and natural history of SSAs, and the molecular and epigenetic aspects are incompletely understood. Endoscopists must be aware of the unique features of SSAs so that the practice of colonoscopic screening for CRC can include optimized detection, removal, and appropriate surveillance of SSAs and other serrated precursor lesions. In this review, we discuss the history, epidemiology, and pathologic aspects of SSAs, as well as a recommended management approach and a discussion of uncertainties and opportunities for future research.

Contributions to the diversity in cryptogamic covers in the mid-Palaeozoic:Nematothallusrevisited

Compression fossils from the Silurian and Devonian of southern Britain, composed of cuticles and tubes, were described by W. H. Lang as the genus Nematothallus and placed, with Prototaxites, in Nematophytales, related neither to algae nor tracheophytes. Dispersed cuticles of Nematothallus and perforated forms assigned to Cosmochlaina were frequently recovered in macerates, their affinities being unresolved. New collections from a Lochkovian locality in the Welsh Borderland permitted the reconstruction of the stratified thalli of these nematophytes; they comprise a superficial cortex (which produced the cuticles) overlying a palisade zone composed of septate, parallel tubes, presumed to be hyphae, and a basal zone comprising wefts of randomly interwoven hyphae. Excellent three dimensional preservation allows the erection of a new species of Nematothallus, N. williamii. A similar anatomy is seen in a new group of fossils with either circular incisions in the cortex or complete separation of thickened cortical cells, presumably comprising a developmental sequence. By their stratified organization the nematophytes differ from extant and extinct algae and bryophytes and the enigmatic Spongiophyton. A complex anatomy and septate tubes suggest affinity with lichenized fungi. Limited data support a fungal rather than embryophyte chemistry, but a photobiont is missing. Nematophytes, globally widespread in cryptogamic covers from mid-Ordovician times, added to the biodiversity in early terrestrial ecosystems and enhanced chemical weathering.

Debris-Rich Basal Ice as a Microbial Habitat, Taylor Glacier, Antarctica

Two ∼4 m vertical sequences of basal ice were collected from tunnels dug into the northern lateral margin of Taylor Glacier, McMurdo Dry Valleys, Antarctica. In both cases the basal sequences exhibit two contrasting ice facies groups; clean (debris-free) and banded dispersed (debris-rich). Debris-rich ices exhibit elevated CO2 and depleted O2 concentrations compared to the clean facies. Bacterial cell numbers, respiration rates, and nutrient concentrations are highest in debris-rich layers. Together, our geochemical and biological data indicate that microbial heterotrophic respiration is likely occurring in situ within the basal ice matrix at ambient temperatures near −15°C. This implies that the basal ice zone of polar glaciers and larger ice sheets is a viable subglacial microbial habitat and active biome of significant volume that has not previously been considered.

Effects of organic acids on the formation of the barrier to radial oxygen loss in roots of Hordeum marinum.

A barrier to radial O2 loss (ROL) is an adaptive trait of many wetland plants, yet the signal(s) for barrier induction remain uncertain. We assessed the effects of monocarboxylic acids produced in waterlogged soils (acetic, propionic, N-butyric and caproic acids) on barrier formation in adventitious roots of the waterlogging tolerant Hordeum marinum Huds. These acids were applied in nutrient solution either individually (at 0.4mM) or as a mixture ('cocktail') at various total concentrations (0.1, 0.4 and 2mM) at pH 6. The barrier to ROL was formed in basal zones of roots exposed to the cocktail at 0.4mM, but not at 0.1mM. Individually, only N-butyric and caproic acids invoked a 'tight' barrier in subapical positions of the roots. These organic acids accelerated deposition of suberin in the hypodermis/exodermis, but did not affect overall root porosity (% gas space). The organic acids also reduced root extension rate and tissue K+; effects were more pronounced at higher concentrations of the cocktail and as the molecular weight of the organic acid increased. Moreover, the cocktail at 2mM and caproic acid at 0.4mM alone induced development of intercellular occlusions, suggesting phytotoxin injury. In summary, even relatively low concentrations of organic acids can promote barrier formation in roots, and the potential toxicity of these compounds was demonstrated by declines in root growth and tissue K+ in the wetland species H. marinum.

Effect of chlorpromazine on rat placenta development

We examined the sequential histopathological changes in the placentas from rats exposed to chlorpromazine. Chlorpromazine was intraperitoneally administered on GD 14 at 50 and 100mg/kg and the placentas were sampled on GDs 14.5, 15, 17 and 21. The incidence of dams with complete fetal resorption was increased from GD 17 up to 20% at 50mg/kg and 44.4% at 100mg/kg. The embryo/fetal weights reduced on GDs 15 and 17 at 50mg/kg and during GDs 15–21 at 100mg/kg. The placental weights reduced on GD 17 at 50mg/kg and during GDs 14.5–21 at 100mg/kg. Histopathologically, in the labyrinth zone, apoptotic cells were scattered in the trophoblastic septa without inhibition of cell proliferation on GDs 14.5 and 15 at 50 and 100mg/kg in a dose-dependent manner. A decrease in trophoblasts led to labyrinth zone hypoplasia. In the basal zone, apoptotic cells were scattered on GDs 14.5 and 15 at 100mg/kg, and most of them appeared to be glycogen cells. A decrease in glycogen cells induced the delayed development of glycogen cell islands and the subsequent remaining glycogen cell islands, and led to the cystic degeneration of glycogen cells. In addition, failure of development of the glycogen cell islands led to the impaired interstitial invasion of the glycogen cells, and then metrial gland hypoplasia occurred.

Calcareous crusts on exposed Pleistocene limestones: A case study from Grand Cayman, British West Indies

Calcareous crusts, which include laminar (up to 6cm thick) and non-laminar calcretes, have developed on ooid grainstones and skeletal wacke/pack/grain/floatstone in the Pleistocene Ironshore Formation exposed at Morgan's Harbour, Tarpon Springs, and Rogers Wreck Point on Grand Cayman, British West Indies. Non-laminar calcretes, which consist largely of micrite with variably altered skeletal fragments and lithoclasts derived from the host limestone, contain peloids in their basal parts. In contrast, the laminar calcretes are formed of porous laminae and low-porosity laminae. Calcified roots are common in the porous laminae but rare in the low-porosity laminae. The δ18O values of calcretes, from ‐5.22‰ to +0.16‰, have a positive correlation with the δ13C values that vary from ‐10.03‰ to ‐6.41‰ at Tarpon Springs, from ‐11.57‰ to ‐5.43‰ at Morgan's Harbour, and from ‐9.89‰ to ‐8.68‰ at Rogers Wreck Point.The non-laminar calcretes reflect progressive micritization of the bedrock with a basal peloidal zone that passes upward into the micrite zone. In contrast, laminar calcretes are attributed to accretionary build-up dictated by microscale processes that were controlled largely by the interplay of plant roots and their associated microorganisms. The positive correlation between the δ18O and δ13C values from the calcareous crusts indicates that evaporation influenced calcite precipitation. The δ13C values of the laminar calcretes record a change from vegetation dominated by C3 plants that grew in a cool, wet climate, to a C3/C4 vegetation that grew in a hotter, drier climate. The Cayman calcretes resemble those found on the Pleistocene Miami Limestone in Florida, and highlight the possibility that these calcareous crusts may reflect regional climates and may therefore enable regional stratigraphic correlation.

English

OBJECTIVE: Efavirenz is a non nucleoside reverse transcriptase inhibitor (NNRTI) commonly employed in combination chemotherapy against HIV-1.However due to its unknown safety profile its use in pregnancy is still in doubt. METHODS: Efavirenz was given to pregnant mice in dose of 50mg/kg &100mg/kg and control mice was given distilled water from 6 th to 15th day of gestation by oral route. On 18 th day mice was sacrificed and placentae and foetuses were taken out. The placenta was processed, cut and stained with H&E for histological observations. RESULTS: The treated placenta shows loss of giant cells and glycogen cells in the basal zone and fibrin deposition and increase thickness of placental barrier in labyrinth zone. CONCLUSION: Efavirenz induces pathological changes in placenta of mice which may cause diminished transfer of nutrients resulting in intrauterine growth retardation.

Tonsil surface epithelium is ideal for monitoring Ki‐67 immunohistochemical staining

To identify an easily obtainable non-neoplastic tissue that can be used as control material for monitoring optimal Ki-67 immunohistochemical staining. Various tissues, including tonsil (60), uterine cervix (31), breast skin (26), oesophagus (15), stomach (15), small intestine (15) and colon (16), were studied in the search for ideal control tissue. Tonsil surface epithelium is superior to other tissues because it displayed an easily recognized Ki-67 staining pattern including high positive (parabasal layer), low positive (intermediate layer) and negative (basal and superficial layers) zones. Moderate to weak staining of the majority of the intermediate cells could serve as a threshold for positive staining. Of the variables potentially affecting staining results that were tested, the pretreatment solution for antigen retrieval had the greatest impact, of which pH 9 EDTA was far better than pH 6 citrate solution. Tonsil surface epithelium is a useful control for monitoring Ki-67 staining. Achieving optimal staining results could minimize variations in Ki-67 index due to differences in the staining methods used by different laboratories.

Toward regeneration of articular cartilage

Articular cartilage is classified as permanent hyaline cartilage and has significant differences in structure, extracelluar matrix components, gene expression profile, and mechanical property from transient hyaline cartilage found in the epiphyseal growth plate. In the process of synovial joint development, articular cartilage originates from the interzone, developing at the edge of the cartilaginous anlagen, and establishes zonal structure over time and supports smooth movement of the synovial joint through life. The cascade actions of key regulators, such as Wnts, GDF5, Erg, and PTHLH, coordinate sequential steps of articular cartilage formation. Articular chondrocytes are restrictedly controlled not to differentiate into a hypertrophic stage by autocrine and paracrine factors and extracellular matrix microenvironment, but retain potential to undergo hypertrophy. The basal calcified zone of articular cartilage is connected with subchondral bone, but not invaded by blood vessels nor replaced by bone, which is highly contrasted with the growth plate. Articular cartilage has limited regenerative capacity, but likely possesses and potentially uses intrinsic stem cell source in the superficial layer, Ranvier's groove, the intra-articular tissues such as synovium and fat pad, and marrow below the subchondral bone. Considering the biological views on articular cartilage, several important points are raised for regeneration of articular cartilage. We should evaluate the nature of regenerated cartilage as permanent hyaline cartilage and not just hyaline cartilage. We should study how a hypertrophic phenotype of transplanted cells can be lastingly suppressed in regenerating tissue. Furthermore, we should develop the methods and reagents to activate recruitment of intrinsic stem/progenitor cells into the damaged site.

Distribution of hydroids along fronds of the kelp Ecklonia radiata

Abundances of organisms generally increase with structural heterogeneity and complexity of habitat. Patterns of distribution of hydroids on the kelp Ecklonia radiata were studied in Australia to examine the generality of this pattern. It was predicted that the cover of hydroids on E. radiata would be greater in the most heterogeneous (e.g., peripheral, crinkled blades) and complex (e.g., middle and bushy) parts of the alga. When different zones were independently compared along laminae of E. radiata, two clear patterns were found. Covers of hydroids in basal, middle and distal zones were greater in the periphery than in the centre of kelp. Second, covers in the periphery and in the centre of kelp were greater in middle than in distal zones and greater in distal than in basal zones. Both patterns conform to those predicted. At a finer spatial resolution, hydroids were significantly more abundant in troughs than on ridges of the peripheral blades of E. radiata. The primary substrata on which kelp was growing (pier-pilings or shark-nets) did not affect the distribution of hydroids. Biological and abiotic factors associated with the kelp itself most probably influence the distribution of hydroids along fronds, but manipulative experiments are needed to establish what models explain these patterns.

Controls on the seasonal deformation of slow-moving landslides

Precipitation drives seasonal velocity changes in slow-moving landslides by increasing pore-water pressure and reducing the effective normal stress along basal shear zones. This pressure change is often modeled as a pore-water pressure wave that diffuses through the landslide body, such that the minimum time required for landslides to respond to rainfall should vary as the square of landslide depth (which often approximates the saturated thickness) and inversely with hydraulic diffusivity. Here, we assess this model with new observations from the landslide-prone Eel River catchment, Northern California. Using satellite radar interferometry (InSAR) time series, precipitation data, and high-resolution topographic data from airborne lidar, we quantify the seasonal dynamics of 10 slow-moving landslides, which share the same lithologic, tectonic, and Mediterranean climate conditions. These slope failures have areas ranging from 0.16 to 3.1 km2, depths that vary from 8 to 40 m, and average downslope velocities of 0.2 to 1.2 m/yr. Each slide exhibits well-defined seasonal velocity changes with a periodicity of ∼1 yr and responds (i.e., accelerates) within 40 days following the onset of rainfall. Despite a five-fold variation in landslide depth, we do not detect systematic differences in response time within the resolution of our observations. Our results could imply that: 1) slides in our study area are sensitive to subtle hydrologic perturbations, 2) the ‘effective’ diffusivity governing slide behavior is much higher than field-derived values because pore pressure transmission and slide dynamics are facilitated by preferential flow paths, particularly cracks related to deformation and seasonal shrink-swell cycles, or 3) a simple one-dimensional linear diffusion model may fail to capture the three-dimensional time-dependent hydrologic changes inherent in an evolving mechanical–hydrologic system, such as a slow-moving landslide.

Paleoarchean sulfur cycle and biogeochemical surface conditions on the early Earth, Barberton, South Africa

This study presents the first multiple sulfur isotope dataset on sulfides from the ca. 3.5–3.2 Ga Onverwacht Group in the Paleoarchean Barberton Greenstone Belt (BGB) of South Africa. In situ δ34SCDT and Δ33S values of pyrite (n=568) are reported from a wide range of hydrothermal, volcanic and sedimentary environments and are used to explore Mid-Archean biogeochemical sulfur cycling. Samples are from fresh drill core collected by the Barberton Scientific Drilling Project that intercepted cherts, metabasalts and sheared ultramafics of the ∼3.3–3.35 Ga Kromberg Formation; the sedimentary units of the ∼3.432 Ga Noisy formation; and the unconformably underlying metabasaltic pillow lavas of the ∼3.472 Ga Hooggenoeg Formation.Pyrite in quartz-carbonate-veins in the lower diamictite of the Noisy sequence records the largest range and most negative δ34SCDT values so far reported from an Archean terrain (δ34SCDT=−55.04 to +27.46‰). The Noisy sediments also contain detrital and diagenetic pyrites with a significant variation in Δ33S of between −0.62 to +1.4‰ and δ34SCDT of between −7.00 and +12.6‰, interpreted to reflect tectonic exposure of these early sediments to atmospheric – shallow marine conditions. Early marine pyrites from the Kromberg Cherts also display strong positive Δ33S values up to +2.50‰ with narrow range in δ34SCDT values (−6.00 to +1.50‰), whereas hydrothermal veins in the basal ultramafic shear zones preserve magmatic values (∼0‰). This study reveals a potential proto-tectonic control on atmospheric, geodynamic and hydrothermal environments available for early sulfate reducing and/or methanogenic microbes in the Paleoarchean.No evidence for microbial sulfate reduction or disproportionation was identified in the Kromberg Cherts, despite previous morphological claims for microbial life. Highly variable and negative δ34SCDT values were found in the Noisy turbidites and Hooggenoeg pillow lava breccia supporting the presence of microbial sulfate reduction in early tectono-sedimentary basins and in the Paleoarchean sub-seafloor, respectively. In light of current controversies surrounding sulfur isotope studies in similar-aged rocks of the Pilbara Craton (West Australia), we argue that microbial elemental sulfur disproportionation was not a preferred metabolic pathway on the Paleoarchean earth.