Lens Core Research Articles

Puzzling parrotfishes: Radiocarbon age validation and updated longevity estimates for western Atlantic species in support of sustainable fisheries management

For management efforts to succeed in Caribbean fisheries, local fishers must support and be willing to comply with fishing regulations. This is more likely when fishers are included in a stock assessment process that utilizes robust scientific evidence, collected in collaboration with fishers, to evaluate the health of fish stocks. Caribbean parrotfishes are important contributors to coral reef ecosystem health while also contributing to local fisheries. Scientifically robust stock assessments require regional species-specific information on age-based key life history parameters, derived from fish age estimates. Evaluation of the accuracy of age estimation methods for fish species is a critical initial step in managing species for long-term sustainable harvest. The current study resulted from a collaborative research program between fish biologists and local fishers investigating age, growth, and reproductive biology of the seven parrotfish species landed in U.S. Caribbean fisheries; specifically, we validated age estimation for stoplight parrotfish Sparisoma viride and queen parrotfish Scarus vetula. This is the first study to directly validate age estimation for any parrotfish species through analysis of Δ14C from eye lens cores. Our age estimation validation results show that enumeration of opaque zones from thin sections of sagittal otoliths for a Sparisoma and a Scarus species provides accurate age estimates. The oldest stoplight parrotfish and queen parrotfish in the Δ14C age estimation validation series were 14 y and 16 y; while the oldest stoplight parrotfish and queen parrotfish we aged to-date using the Δ14C validated age estimation method were 20 y and 21 y, respectively. Fish longevity (maximum age attained/life span) is a key life history parameter used for estimation of natural mortality, survivorship, and lifetime reproductive output. Past reviews on parrotfishes from the Pacific and Atlantic concluded that most Caribbean/western Atlantic parrotfish species are relatively short-lived with estimated maximum ages ranging from 3–9 y. However, information from our collaborative research in the U.S. Caribbean combined with recently published age estimates for Brazilian parrotfish species indicate that many western Atlantic parrotfishes are relatively long-lived with several species attaining maximum ages in excess of 20 y.

Технология предварительной радиальной ИАГ-лазерной факофрагментации в хирургическом лечении катаракты

Purpose. To represent the technology of preliminary radial YAG laser phacofragmentation in the surgical treatment of cataracts. Material and methods. The technology of preliminary radial YAG laser phacofragmentation has been used in the Kaluga branch of the S. Fyodorov Eye Microsurgery Federal State Institution since 2016. The basis of the technology is the transcorneal endocapsular formation of radial cracks of the lens core for its subsequent fragmentation during ultrasonic phacoemulsification of cataracts (FEC). The total number of pulses ranges from 95 to 150. Results. In the Kaluga branch of the S. Fyodorov Eye Microsurgery Federal State Institution, preliminary radial YAG laser phacofragmentation was performed on 9468 eyes with cataracts of 2–4 degrees of density from 2016 to 2023. After YAG laser fragmentation of the lens core, its radial separation occurs according to the «snowflake» type, which consists of 3 layers and «petals» extending from cavitation bubbles that clearly outline the core. The clinical and functional state of the eyes after preliminary YAG laser phacofragmentation indicated the absence of reactive inflammation from the anterior and posterior segment of the eye, which was confirmed by biomicroscopy and ultrasound ophthalmoscanning data. Conclusion. The technology of preliminary radial YAG laser phacofragmentation is a safe and effective method that allows you to achieve uniform separation of lens fibers along the formed fragmentation zones, which correspond to subsequent nuclear fracture zones during the nuclear fragmentation stage during ultrasonic FEC. Key words: radial YAG laser phacofragmentation, cataract, ultrasonic phacoemulsification of cataract

Role of micelle dynamics in enhancing cyclosporine uptake in hyaluronic acid-contact lenses for improved critical lens properties in dry eye management

Loading hydrophobic drugs, such as cyclosporine, into contact lenses for dry eye treatment is challenging due to low drug uptake during soaking and alterations in critical lens properties, including wettability, water content, and optical transmission. This study aimed to investigate the role of micelle dynamics in enhancing cyclosporine loading into hyaluronic acid (HA)-contact lenses while improving their critical properties. The findings indicate that Pluronic® F127 (342 nm) and Tween® 80 (296 nm) micelles could encapsulate cyclosporine within the lens core, with Pluronic® F127 demonstrating superior surface tension on Langmuir-Blodgett trough compared to Tween® 80. The uptake of cyclosporine-loaded micelles (13.43–20.92 µg) was higher compared to cyclosporine without micelles (CY-CL = 8.80 µg). Moreover, the cyclosporine-loaded micelles improved the lens’s contact angle (wettability), equilibrium water content, and optical transmission compared to cyclosporine without micelles. The in vitro test showed sustained release of cyclosporine from contact lenses over 120 h or 96 h using Pluronic®-micelles or Tween® 80-micelles, respectively. In animal study, the 0.05% w/v Pluronic® F127-CL and 0.0015% w/v Tween 80-CL lenses showed an initial release of 2.54 µg/ml and 3.59 µg/ml, respectively, with the release profile extending over 48 h. Wear of the micelle-laden lenses resulted in lower levels of IL-6 compared to cyclosporine eye drops. In conclusion, Pluronic® F127 micelles demonstrated greater stability, sustained release, and improved outcomes compared to Tween® 80 micelles. These findings suggest the potential of micelles-laden contact lenses as a promising alternative to eye drops for improved dry eye management.

Caribbean deepwater snappers: Application of the bomb radiocarbon age estimation validation in understanding aspects of ecology and life history.

Reef fishes have been utilized as food fish throughout the U.S. Caribbean and Gulf of Mexico waters for centuries, with increasing fishing effort in recent decades. As a result, many species have experienced declines in landings, including deepwater snappers such as queen snapper Etelis oculatus and blackfin snapper Lutjanus buccanella. However, little to no peer-reviewed published research exists on basic life history parameters for either species. Confirming the accuracy of an age estimation method for a fish species is essential for ensuring sustainable fisheries management. This is because in the assessment of fisheries species population age-based parameters, including longevity, age at sexual maturity, growth rate, mortality, age-specific reproductive output, and lifetime reproductive output, are important in understanding overall life history strategies of managed stocks. The past stock assessment on U.S. Caribbean queen snapper utilized an estimated longevity of 8 y, derived from length frequencies for fish from St. Lucia. Blackfin snapper has an estimated longevity of 27 y based on a relatively small study from offshore waters of the southeastern U.S. The focus of our investigation was to estimate maximum longevity of two data-poor species in the U.S. Caribbean. The accuracy of ageing methods was tested via bomb radiocarbon age estimation validation and effects of depth on Δ14C in otolith cores and eye lens core values were examined. Results from our work indicate a maximum validated age of 45 y for queen snapper, and 43 y for blackfin snapper. Our findings indicate queen snapper and blackfin snapper are long-lived (> 40 y). The resulting Δ14C comparison between eye lens cores and otolith cores has important implications for the study of age validation, specifically when deepwater species are involved.

Species independence of eye lens dimensions in teleosts and elasmobranchs.

The vertebrate eye lens grows incrementally, adding layers of elongated, tightly packed lens fiber cells at the outer margin of the lens. With subsequent growth, previously-deposited fiber cells degrade, leaving a region of fully denucleated and organelle-free cells which are responsible for the high transparency and low light scattering characteristics of the lens. The objective of this study was to determine if the horizon separating the gelatinous outer cortex of the lens from its hardened interior occurred at a consistent location within the lens of several teleost and elasmobranch fish species, and could be linked to fiber cell morphology or function. A fixed ratio of 0.69±0.01 of hardened eye lens diameter (HD) to overall eye lens diameter (LD) was observed in a broad size range of Atlantic cod (Gadus morhua), haddock (Melanogrammus aeglefinus), thorny skate (Amblyraja radiata) and round ray (Rajella fyllae). The location of the hardened lens horizon was similar to that reported for optical plasticity and spherical aberration, but not that of fiber cell denucleation, suggesting that fiber cell dehydration continues after the loss of internal organelles. Our findings support a previous suggestion that the maintenance of optical quality during fish eye lens growth requires a precisely-fixed HD:LD ratio, while the ubiquity of a fixed ratio across fish taxa may suggest that many fish species possess a common refractive index profile. The linear relationship between HD and fish length should allow fish length to be backcalculated from the diameter of the isolated lens core, thus aiding research using isotope ratios of lens laminae or inner cores to reconstruct early life history events.

Eye lens-derived Δ14C signatures validate extreme longevity in the deepwater scorpaenid blackbelly rosefish (Helicolenus dactylopterus)

Many members of the scorpaenid subfamily: Sebastinae (rockfishes and their relatives) exhibit slow growth and extreme longevity (> 100 y), thus are estimated to be vulnerable to overfishing. Blackbelly rosefish (Helicolenus dactylopterus) is a deepwater sebastine whose longevity estimates range widely, possibly owing to different regional levels of fisheries exploitation across its Atlantic Ocean range. However, age estimation has not been validated for this species and ageing for sebastines in general is uncertain. We performed age validation of northern Gulf of Mexico blackbelly rosefish via an application of the bomb radiocarbon chronometer which utilized eye lens cores instead of more traditional otolith cores as the source of birth year Δ14C signatures. The correspondence of eye lens core Δ14C with a regional reference series was tested with a novel Bayesian spline analysis, which revealed otolith opaque zone counts provide accurate age estimates. Maximum observed longevity was 90 y, with 17.5% of individuals aged to be > 50 y. Bayesian growth analysis, with estimated length-at-birth included as a prior, revealed blackbelly rosefish exhibit extremely slow growth (k = 0.08 y−1). Study results have important implications for the management of blackbelly rosefish stocks, as extreme longevity and slow growth imply low resilience to fishing pressure.

Highly variable length-at-age in vermilion snapper (Rhomboplites aurorubens) validated via Bayesian analysis of bomb radiocarbon

Vermilion snapper (Rhomboplites aurorubens) has been reported to exhibit highly variable length-at-age, while age estimates derived from otoliths are often imprecise (i.e., average percent error ≥ 8.0%). This has led to questions whether the observed variability in length-at-age is due to variability in growth or ageing error. The current study was conducted to address this by testing the accuracy of otolith-derived age estimates via age validation. Age was estimated by enumerating opaque zones in otolith thin sections observed under a dissecting microscope with transmitted light. Then, age validation was performed by applying the bomb radiocarbon (14C) chronometer, where vermilion snapper birth year Δ14C values were derived from eye lens cores for contemporary samples and otolith cores for archived samples. Otolith-derived age estimates were found to be accurate, with the maximum validated age being 28 years. Results of Bayesian regression modeling indicated there was no significant relationship between eye lens Δ14C variance and fish length (p = 0.93). Further Bayesian regression modeling demonstrated vermilion snapper do not exhibit sexually dimorphic growth (p = 0.91). Study results have important implications for vermilion snapper assessment and management, as variable growth reduces the accuracy in assigning age based on length. Moreover, the approach reported here could be applied to test the accuracy of highly variable length-at-age estimates in other marine fishes.

Application of the bomb radiocarbon chronometer with eye lens core Δ14C for age validation in deepwater reef fishes

Eye lens core Δ14C of Gulf of Mexico outer shelf and upper slope reef fishes matched a regional Δ14C reference time series, but otolith cores were depleted in 14C relative to the reference series. This is due to C in eye lens protein being derived from metabolic sources, with the ultimate source being epipelagic phytoplankton. In contrast, otolith C is derived mainly (70%–80%) from dissolved inorganic C, which is depleted in 14C beyond the epipelagic. Analyzing Δ14C in eye lens cores provides a novel approach for validating age estimates of deepwater (>200 m) fishes, which were unresolved in earlier applications of the bomb 14C chronometer.

Early Stage UV-B Induced Molecular Modifications of Human Eye Lens γD-Crystallin.

In the human eye lenses, the crystallin proteins facilitate transparency, light refraction, as well as UV light protection. A deregulated balanced interplay between α-, β-, and γ-crystallin can cause cataract. γD-crystallin (hγD) is involved in the energy dissipation of absorbed UV light by energy transfer between aromatic side chains. Early UV-B induced damage of hγD with molecular resolution is studied by solution NMR and fluorescence spectroscopy. hγD modifications are restricted to Tyr 17 and Tyr 29 in the N-terminal domain, where a local unfolding of the hydrophobic core is observed. None of the tryptophan residues assisting fluorescence energy transfer is modified and hγD is remained soluble over month. Investigating isotope-labeled hγD surrounded by eye lens extracts from cataract patients reveals very week interactions of solvent-exposed side chains in the C-terminal hγD domain and some remaining photoprotective properties of the extracts. Hereditary E107A hγD found in the eye lens core of infants developing cataract shows under the here used conditions a thermodynamic stability comparable to the wild type but an increased sensitivity toward UV-B irradiation.

Natal Origin Differentiation Using Eye Lens Stable Isotope Analysis

AbstractNatal origin determination can be critical to understanding the movement, recruitment, and stock discrimination of fish populations. We investigated the utility of eye lens stable isotope analysis as a natural marker to determine natal origins, specifically the differentiation of stocked versus naturally reproduced individuals. We compared isotopic values for stocked and naturally reproduced Rainbow Trout Oncorhynchus mykiss in the North Platte River (Wyoming, USA) and found that the metabolically inert core of the eye lens retained hatchery feed values as the fish grew poststocking. The stable isotope values of eye lens cores from stocked Rainbow Trout were >15‰ higher for δ34S and >4‰ higher for δ13C than naturally reproduced fish. The values for δ15N proved to be a less useful indicator for natal origin than sulfur and carbon. These high carbon and sulfur isotopic values were retained in the core, despite subsequent lens layers showing a dietary shift to natural prey items poststocking. Rainbow Trout formed over 10 layers at age 0, decreasing to an estimated one to two layers during subsequent years. Eye lens stable isotope analysis represents an additional tool for researchers and managers to use natural isotopic markers to accurately assess natal origins and hatchery contributions to fish populations.

P–T–t–D records of Early Palaeozoic Andean‐type shortening of a hot active margin: The Dunhuang block in NW China

AbstractHigh‐pressure (HP) granulites form either in the domain of the subducted plate during continental collision or in supra‐subduction systems where the thermally softened upper plate is shortened and thickened. Such a discrepancy in tectonic setting can be evaluated by metamorphic pressure–temperature–time‐deformation (P–T–t–D) paths. In the current study, P–T–t–D paths of Early Palaeozoic HP granulite facies rocks, in the form of metabasic lenses enclosed in migmatitic metapelite, from the Dunhuang block, NW China, are investigated in order to constrain the nature of the HP rocks and shed light on the geodynamic evolution of a modern hot orogenic system in an active margin setting. The rocks show a polyphase evolution characterized by (1) relics of horizontal or gently dipping fabric (S1) preserved in cores of granulite lenses and in garnet porphyroblasts, (2) a N‐S trending sub‐vertical fabric (S2) preserved in low‐strain domains and (3) upright folds (F3) associated with a ubiquitous steep E‐W striking axial planar foliation (S3). Garnet in the granulites preserves relics of a prograde mineral assemblage M1a equilibrated at ~11.5 kbar and ~770–780°C, whereas the matrix granulite assemblage (M1b) from the S1 fabric attained peak pressure at ~13.5 kbar and ~850°C. The granulites were overprinted at ~8–11 kbar and ~850–900°C during crustal melting (M2) followed by partial re‐equilibration (M3) at ~8 kbar and ~625°C. A garnet Lu–Hf age of 421.6 ± 1.2 Ma dates metamorphism M1, while a garnet Sm–Nd age of 385.3 ± 4.0 Ma reflects M3 cooling of the granulites. The mineral assemblage, M1, of the host migmatitic metapelite formed at ~9–12.5 kbar and ~760–810°C, partial melting and migmatization (M2) occurred at ~7 kbar and ~760°C and re‐equilibration (M3) at ~5–6 kbar and ~675°C. A garnet Lu–Hf age of 409.7 ± 2.3 Ma dates thermal climax (M2) and a garnet Sm–Nd age of 356 ± 11 Ma constrains M3 for the migmatitic metapelites. The timing of this late phase is also bracketed by an emplacement age of syntectonic granite dated at c. 360 Ma. Decoupling of M1 and M2 P–T evolutions between the mafic granulites and migmatitic metapelites indicates their different positions in the crustal column, while the shared pressure–temperature (P–T) evolution M3 suggests formation of a mélange‐like association during the late stages of orogeny. The high‐pressure event D1‐M1 is interpreted as a result of Late Silurian–Early Devonian moderate crustal thickening of a thermally softened and thinned pre‐orogenic crust. The high‐temperature (HT) re‐equilibration D2‐M2 is interpreted as a result of Mid‐Devonian shortening of the previously thickened crust, possibly due to ‘Andean‐type’ underthrusting. The D3‐M3 event reflects Late Devonian supra‐subduction shortening and continuous erosion of the sub‐crustal lithosphere. This tectono‐metamorphic sequence of events is explained by polyphased Andean‐type deformation of a ‘Cascadia‐type’ active margin, which corresponds to a supra‐subduction tectonic switching paradigm.

Oxidation of active cysteines mediates protein aggregation of S10R, the cataract-associated mutant of mouse GammaB-crystallin.

The Ser10 to Arg mutation in mouse γB-crystallin (MGB) has been associated with protein aggregation, dense nuclear opacity, and the degeneration of fiber cells in the lens core. Overexpression of the gap junction protein, connexin 46 (Cx46), was found to suppress the nuclear opacity and restore normal cell-cell contact. However, the molecular basis for the protein aggregation and related downstream effects were not evident from these studies. Here, we provide a comparison of the structures and solution properties of wild type MGB and the S10R mutant in vitro and show that, even though the mutation does not directly involve cysteine residues, some cysteines in the mutant protein are activated, leading to the enhanced formation of intermolecular disulfide-crosslinked protein aggregates relative to the wild-type. This occurs even as the protein structure is essentially unaltered. Thus, the primary event is enhanced protein aggregation due to the disulfide crosslinking of the mutant protein. We suggest that these aggregates eventually get deposited on fiber cell membranes. Since the gap junction protein, Cx46 is involved in the transport of reduced glutathione, we posit that these deposits interfere in Cx46-mediated glutathione transport and facilitate the oxidative stress-mediated downstream changes. Overexpression of Cx46 suppresses such oxidative aggregation. These studies provide a plausible explanation for the protein aggregation and other changes that accompany this mutation. If indeed cysteine oxidation is the primary event for protein aggregation also in vivo, then the S10R mutant mouse, which is currently available, could serve as a viable animal model for human age-onset cataract.

INCIDENCE OF PSEUDOEXFOLIATION SYNDROME AND GLAUCOMA IN A SET OF MORE THAN 14,000 EYES OF PATIENTS OPERATED FOR A CATARACT.

Evaluation of the incidence of pseudoexfoliation (PEX) syndrome and glaucoma in cataract patients operated at our Clinic, with an analysis of possible complications. Retrospective evaluation of medical records of PEX syndrome patients who have undergone cataract surgery at the Gemini Eye Clinic Ostrava-Hrusov was undertaken. The study period was from November 2016 to April 2021. The evaluated parameters were the incidence of PEX syndrome, age and gender of patients, intraocular pressure (IOP) before the surgery, pre-existing therapy of previously diagnosed secondary glaucoma and the occurrence of perioperative complications. In the study period of 4.5 years, out of the total number of 14 167 operated eyes with cataracts there were 852 eyes of 689 patients with PEX syndrome diagnosed at our Clinic, i.e. 6.0 %. The mean age was 76.9 years, the median 77 years, range 54-100 years. The observed pathology was more common in women at a ratio of 1.84: 1 (552: 300). Elevation of IOP above 21 mmHg was recorded in 118 eyes, in 14 of them IOP reached values over 30 mmHg. Diagnosed and long-term treated secondary glaucoma was confirmed by 153 patients (204 eyes), out of which 22 eyes have undergone antiglaucoma laser (19 eyes) and / or surgery (5 eyes) in the anamnesis. Perioperatively, we recorded the following pathological findings accompanying the occurrence of PEX syndrome in 231 eyes. Most often it was poor artificial mydriasis (189 eyes), then subluxation of the lens (31 eyes) or zonular fragility (17 eyes). To reduce the risk of perioperative and postoperative complications, implantation of a capsular tension ring was indicated in 20 eyes. Complications during the procedure occurred in 11 eyes, of which 8 eyes were diagnosed with advanced cataract. PEX syndrome and glaucoma are relatively common diseases that can complicate the lives of patients and eye surgeons. The incidence of PEX syndrome in our cataract patients was 6 %. Proper diagnosis of this disease is important not only for the possible occurrence of numerous complications during and after cataract surgery, but also for the possible presence of secondary glaucoma. It also serves to detect possible involvement of the contralateral eye. In addition, due to the involvement of practically all tissues in the body, the patient is endangered by numerous, especially vascular comorbidities. For these reasons, we find it appropriate that these patients are observed by other healthcare specialists. In our experience, early indication of cataract surgery is important to achieve a lower degree of zonular fragility and a softer lens core. In addition, lower levels of proinflammatory pseudoexfoliation material occur in the anterior segment of the eye in the early stages, which may have a beneficial effect on the postoperative healing.

СПОСІБ ОЦІНЮВАННЯ ВПЛИВУ ХІРУРГІЧНОГО ЛІКУВАННЯ КАТАРАКТИ НА ПРОГРЕСУВАННЯ ВІКОВОЇ МАКУЛЯРНОЇ ДЕГЕНЕРАЦІЇ

У роботі наводяться результати дослідження впливу хірургічного лікування вікової катарак-ти на прогресування вікової макулярної дегенерації (ВМД).Мета роботи – розробити спосіб оцінки впливу хірургічного лікування катаракти на прогре-сування вікової макулярної дегенерації.У 82 хворих (93 ока) вивчено вплив параметрів факоемульсифікації (ФЕК), операційні тапісляопераційні ускладнення на прогресування ВМД. Встановлено, що факторами ризикупрогресування ВМД після хірургічного лікування є щільність ядра кришталика по Buratto,тривалість операції, обсяг іригаційної рідини, показник кумулятивної розсіяної енергії (се-редня потужність і експозиція лінійного ультразвуку та середня торсійна амплітуда і тор-сійний час), післяопераційне запалення. Розроблено шкалу бальної оцінки прогресуваннявікової макулярної дегенерації після хірургічного лікування катаракти.

Spatially Resolved Proteomic Analysis of the Lens Extracellular Diffusion Barrier.

PurposeThe presence of a physical barrier to molecular diffusion through lenticular extracellular space has been repeatedly detected. This extracellular diffusion barrier has been proposed to restrict the movement of solutes into the lens and to direct nutrients into the lens core via the sutures at both poles. The purpose of this study is to characterize the molecular components that could contribute to the formation of this barrier.MethodsThree distinct regions in the bovine lens cortex were captured by laser capture microdissection guided by dye penetration. Proteins were digested by Lys C and trypsin. Mass spectrometry–based proteomic analysis followed by gene ontology and protein interaction network analysis was performed.ResultsDye penetration showed that fiber cells first shrink the extracellular spaces of the broad sides followed by closure of the extracellular space between narrow sides at a normalized lens distance (r/a) of 0.9. Accompanying the closure of extracellular space of the broad sides, dramatic proteomic changes were detected, including upregulation of several cell junctional proteins. AQP0 and its interacting partners, Ezrin and Radixin, were among a few proteins that were upregulated, accompanying the closure of extracellular space of the narrow sides, suggesting a particularly important role for AQP0 in controlling the narrowing of the extracellular spaces between fiber cells. The results also provided important information related to biological processes that occur during fiber cell differentiation such as organelle degradation, cytoskeletal remodeling, and glutathione synthesis.ConclusionsThe formation of a lens extracellular diffusion barrier is accompanied by significant membrane and cytoskeletal protein remodeling.

Quantitative X-ray tomographic analysis reveals calcium precipitation in cataractogenesis

Cataracts, named for pathological light scattering in the lens, are known to be associated with increased large protein aggregates, disrupted protein phase separation, and/or osmotic imbalances in lens cells. We have applied synchrotron phase contrast X-ray micro-computed tomography to directly examine an age-related nuclear cataract model in Cx46 knockout (Cx46KO) mice. High-resolution 3D X-ray tomographic images reveal amorphous spots and strip-like dense matter precipitates in lens cores of all examined Cx46KO mice at different ages. The precipitates are predominantly accumulated in the anterior suture regions of lens cores, and they become longer and dense as mice age. Alizarin red staining data confirms the presence of calcium precipitates in lens cores of all Cx46KO mice. This study indicates that the spatial and temporal calcium precipitation is an age-related event associated with age-related nuclear cataract formation in Cx46KO mice, and further suggests that the loss of Cx46 promotes calcium precipitates in the lens core, which is a new mechanism that likely contributes to the pathological light scattering in this age-related cataract model.

Monazite recorded Paleoproterozoic granulite-facies metamorphism and Triassic fluid modification of the Weihai pelitic granulite, Sulu orogen

Monazite is an important accessory mineral in the pelitic granulites (Weihai area, Sulu orogen), and is also a powerful monitor for understanding the metamorphic evolution of the granulites. The pelitic granulites incongruously occur as lenses in granitic gneisses. The lithologies of the lenses gradually change from core to margin: The undeformed coarse-grained granulite, the foliated fine-grained granulite, the garnet-biotite-gneiss, and the migmatized granulite. The lens cores mostly preserve a peak granulite-facies metamorphic mineral assemblage of garnet + plagioclase (antiperthite) + quartz + sillimanite + biotite with accessory minerals of rutile, zircon, and monazite. The lens margins display a fluid-induced retrogression. In order to decipher the metamorphic processes of the pelitic granulites, a combined study of BSE imaging, U-Pb dating, and trace element composition for the monazites from the metapelitic lens were conducted. Monazites from the undeformed coarse-grained granulite only record a Paleoproterozoic age (1832±7 Ma, n=40). Monazites from the other lithologies yield the inherited Paleoproterozoic age and Triassic overgrowth age. For example, monazites from the migmatite yield intercept ages of 1818±10 and 211±22 Ma (n=56) with Triassic concordant age of 223.8±2.9 Ma. The Paleoproterozoic monazites are characterized by remarkable depletion in HREE and Y with obviously negative Eu anomalies, indicating their formation equilibrated with garnet and feldspar under granulite-facies conditions. During Triassic fluid modification, the monazite bright rims assimilated Th and Si but released U, HREE, Y, and P. This process resulted in the Triassic overgrowth monazites have higher HREE and Y contents, and lower Th and U contents with relatively lower Th/U ratios. Thus, the monazites in the pelitic granulites recorded a Paleoproterozoic metamorphic event and Triassic fluid modification. The Weihai pelitic granulites might have a tectonic affinity with the North China Craton. Therefore, the Paleoproterozoic pelitic granulites were mechanically drawn into the orogen during the Triassic continental collision, and subsequently were remoulded by the fluids during its exhumation.

Novel mitochondrial derived Nuclear Excisosome degrades nuclei during differentiation of prosimian Galago (bush baby) monkey lenses.

The unique cellular organization and transparent function of the ocular lens depend on the continuous differentiation of immature epithelial cells on the lens anterior surface into mature elongated fiber cells within the lens core. A ubiquitous event during lens differentiation is the complete elimination of organelles required for mature lens fiber cell structure and transparency. Distinct pathways have been identified to mediate the elimination of non-nuclear organelles and nuclei. Recently, we reported the discovery of a unique structure in developing fiber cells of the chick embryo lens, called the Nuclear Excisosome, that is intractably associated with degrading nuclei during lens fiber cell differentiation. In the chick lens, the Nuclear Excisosome is derived from projections of adjacent cells contacting the nuclear envelope during nuclear elimination. Here, we demonstrate that, in contrast to the avian model, Nuclear Excisosomes in a primate model, Galago (bush baby) monkeys, are derived through the recruitment of mitochondria to form unique linear assemblies that define a novel primate Nuclear Excisosome. Four lenses from three monkeys aged 2–5 years were fixed in formalin, followed by paraformaldehyde, then processed for Airyscan confocal microscopy or transmission electron microscopy. For confocal imaging, fluorescent dyes labelled membranes, carbohydrate in the extracellular space, filamentous actin and nuclei. Fiber cells from Galago lenses typically displayed prominent linear structures within the cytoplasm with a distinctive cross-section of four membranes and lengths up to 30 μm. The outer membranes of these linear structures were observed to attach to the outer nuclear envelope membrane to initiate degradation near the organelle-free zone. The origin of these unique structures was mitochondria in the equatorial epithelium (not from plasma membranes of adjacent cells as in the chick embryo model). Early changes in mitochondria appeared to be the collapse of the cristae and modification of one side of the mitochondrial outer membrane to promote accumulation of protein in a dense cluster. As a mitochondrion surrounded the dense protein cluster, an outer mitochondrial membrane enclosed the protein to form a core and another outer mitochondrial membrane formed the outermost layer. The paired membranes of irregular texture between the inner core membrane and the outer limiting membrane appeared to be derived from modified mitochondrial cristae. Several mitochondria were involved in the formation and maturation of these unique complexes that apparently migrated around the fulcrum into the cytoplasm of nascent fiber cells where they were stabilized until the nuclear degradation was initiated. Thus, unlike in the chick embryo, the Galago lenses degraded nuclear envelopes with a Nuclear Excisosome derived from multiple mitochondria in the epithelium that formed novel linear assemblies in developing fiber cells. These findings suggest that recruitment of distinct structures is required for Nuclear Excisosome formation in different species.

Eye lens Δ14C validates otolith-derived age estimates of Gulf of Mexico reef fishes

We tested whether Δ14C values of eye lens protein (crystallin) formed in early life could be utilized to validate marine bony fish age estimates via the bomb radiocarbon chronometer. The slope of the relationship between red snapper (Lutjanus campechanus; n = 8; 0 to 27 years old), otolith and eye lens core Δ14C values was not significantly different than 1, which was also true for seven additional reef fish species (n = 21; 0 to 24 years old). Results demonstrate eye lens core Δ14C can be utilized to validate age estimates of marine fishes, which will be useful in numerous age validation applications.

ОБЗОР ИССЛЕДОВАНИЙ СРЕДИЗЕМНОМОРСКИХВНУТРИТЕРМОКЛИННЫХ ВИХРЕЙ В АТЛАНТИЧЕСКОМ ОКЕАНЕ

The Mediterranean waters (MW) occupy intermediate depths (500–1500 m) of the Northeast Atlantic. These waters are transported by the bottom current to the Atlantic through the Strait of Gibraltar. Salinity of these waters exceeds 37.0 and the temperature is warmer than 13°C. In addition to the MW transport by the quasi-continuous “stream” component there is an irregular “lens” component. This component consists of intra-thermocline eddies or long-living MW lenses, the “Meddies”, which are formed west of the Iberian Peninsula and then spread over long distances. These lenses desintegrated in time and support the salt MW “tongue” far from the Strait of Gibraltar. The goal of this work is to give a brief review of the main research of this phenomenon and to determine the criteria to distinguish MW lenses based on selected field data. Peculiarities of the space and time evolution of the MW lenses are shown based on the T,S-analysis of the lens cores.