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1.
J Cardiothorac Surg ; 19(1): 49, 2024 Feb 03.
Artigo em Inglês | MEDLINE | ID: mdl-38310253

RESUMO

BACKGROUND: Right-sided infective endocarditis (RSIE) is a relatively uncommon condition which is difficult to distinguish from thrombus, particularly when the site of infection or the patient's symptoms are atypical. There have been few reports exploring the differential diagnostic and analytical features between RSIE and thrombus. CASE PRESENTATION: Here, we presented two cases of RSIE-one involving the tricuspid valve and the other affecting the pulmonary artery. Notably, the second case was initially misdiagnosed as thrombus based on the findings of by computed tomography angiography(CTA). CONCLUSIONS: Vegetation and thrombus can be distinguished according to the nature of the mass, its attachment location, and the clinical manifestation. Echocardiography can observe both the location and size of the mass, and the dynamic changes in cardiac hemodynamics and cardiac morphology, thereby facilitating an effective distinction between vegetation and thrombus.


Assuntos
Endocardite Bacteriana , Endocardite , Trombose , Humanos , Endocardite/diagnóstico por imagem , Ecocardiografia , Valva Tricúspide/diagnóstico por imagem , Tomografia Computadorizada por Raios X , Trombose/diagnóstico por imagem , Endocardite Bacteriana/diagnóstico por imagem
2.
Nat Commun ; 15(1): 376, 2024 Jan 08.
Artigo em Inglês | MEDLINE | ID: mdl-38191461

RESUMO

Extant cicada (Hemiptera: Cicadoidea) includes widely distributed Cicadidae and relictual Tettigarctidae, with fossils ascribed to these two groups based on several distinct, minimally varying morphological differences that define their extant counterparts. However, directly assigning Mesozoic fossils to modern taxa may overlook the role of unique and transitional features provided by fossils in tracking their early evolutionary paths. Here, based on adult and nymphal fossils from mid-Cretaceous Kachin amber of Myanmar, we explore the phylogenetic relationships and morphological disparities of fossil and extant cicadoids. Our results suggest that Cicadidae and Tettigarctidae might have diverged at or by the Middle Jurassic, with morphological evolution possibly shaped by host plant changes. The discovery of tymbal structures and anatomical analysis of adult fossils indicate that mid-Cretaceous cicadas were silent as modern Tettigarctidae or could have produced faint tymbal-related sounds. The discovery of final-instar nymphal and exuviae cicadoid fossils with fossorial forelegs and piercing-sucking mouthparts indicates that they had most likely adopted a subterranean lifestyle by the mid-Cretaceous, occupying the ecological niche of underground feeding on root. Our study traces the morphological, behavioral, and ecological evolution of Cicadoidea from the Mesozoic, emphasizing their adaptive traits and interactions with their living environments.


Assuntos
Hemípteros , Animais , Filogenia , Âmbar , Ecossistema , Membro Anterior , Ninfa
3.
Anat Rec (Hoboken) ; 2023 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-37161734

RESUMO

A complete and well-preserved forewing assigned to the orthopteran insect Parahagla cheni Xu, Fang and Zhang, 2023 is described from the Lower Jurassic Badaowan Formation of the northwestern Junggar Basin (Karamay, Xinjiang, northwestern China), based on which the species is diagnostically revised. It represents the earliest record of the subfamily Chifengiinae under the family Prophalangopsidae. The subfamily Chifengiinae is reviewed and a key to its genera and species is provided in the discussion. A further discuss of the palaeobiogeographic distribution of Chifengiinae shows that the subfamily probably first appeared in the Palaeoarctic in the earliest Jurassic, and later quickly migrated and occupied most areas of eastern Palaeoarctic from the Middle Jurassic to the Early Cretaceous.

4.
Anat Rec (Hoboken) ; 2023 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-36641784

RESUMO

A new Middle Triassic (Ladinian) planthopper of the family Surijokocixiidae (Surijokocixioidea, Fulgoromorpha) from the Tongchuan Formation in Shaanxi, NW China is established as Sinosurijikocixius tongchuanensis gen. et sp. nov. All the known taxa assigned to Surijokocixiidae are reviewed and compared. The palaeogeographic distributional pattern of Surijokocixiidae from the middle Permian to Late Triassic is summarized.

5.
Proc Natl Acad Sci U S A ; 119(51): e2210601119, 2022 12 20.
Artigo em Inglês | MEDLINE | ID: mdl-36508660

RESUMO

Acoustic communication has played a key role in the evolution of a wide variety of vertebrates and insects. However, the reconstruction of ancient acoustic signals is challenging due to the extreme rarity of fossilized organs. Here, we report the earliest tympanal ears and sound-producing system (stridulatory apparatus) found in exceptionally preserved Mesozoic katydids. We present a database of the stridulatory apparatus and wing morphology of Mesozoic katydids and further calculate their probable singing frequencies and analyze the evolution of their acoustic communication. Our suite of analyses demonstrates that katydids evolved complex acoustic communication including mating signals, intermale communication, and directional hearing, at least by the Middle Jurassic. Additionally, katydids evolved a high diversity of singing frequencies including high-frequency musical calls, accompanied by acoustic niche partitioning at least by the Late Triassic, suggesting that acoustic communication might have been an important driver in the early radiation of these insects. The Early-Middle Jurassic katydid transition from Haglidae- to Prophalangopsidae-dominated faunas coincided with the diversification of derived mammalian clades and improvement of hearing in early mammals, supporting the hypothesis of the acoustic coevolution of mammals and katydids. Our findings not only highlight the ecological significance of insects in the Mesozoic soundscape but also contribute to our understanding of how acoustic communication has influenced animal evolution.


Assuntos
Ortópteros , Animais , Ortópteros/anatomia & histologia , Acústica , Som , Audição , Insetos , Mamíferos , Evolução Biológica
6.
Geobiology ; 20(3): 363-376, 2022 05.
Artigo em Inglês | MEDLINE | ID: mdl-35212124

RESUMO

Fossilized tree resin, or amber, commonly contains fossils of animals, plants and microorganisms. These inclusions have generally been interpreted as hollow moulds or mummified remains coated or filled with carbonaceous material. Here, we provide the first report of calcified and silicified insects in amber from the mid-Cretaceous Kachin (Burmese) amber. Data from light microscopy, scanning electron microscopy (SEM), energy-dispersive and wavelength-dispersive X-ray spectroscopy (EDX and WDX), X-ray micro-computed tomography (Micro-CT) and Raman spectroscopy show that these Kachin fossils owe their preservation to multiple diagenetic mineralization processes. The labile tissues (e.g. eyes, wings and trachea) mainly consist of calcite, chalcedony and quartz with minor amounts of carbonaceous material, pyrite, iron oxide and phyllosilicate minerals. Calcite, quartz and chalcedony also occur in cracks as void-filling cements, indicating that the minerals formed from chemical species that entered the fossil inclusions through cracks in the resin. The results demonstrate that resin and amber are not always closed systems. Fluids (e.g. sediment pore water, diagenetic fluid and ground water) at different burial stages have chances to interact with amber throughout its geological history and affect the preservational quality and morphological fidelity of its fossil inclusions.


Assuntos
Âmbar , Quartzo , Âmbar/química , Animais , Carbonato de Cálcio , Fósseis , Insetos , Microtomografia por Raio-X
7.
Micromachines (Basel) ; 12(7)2021 Jun 25.
Artigo em Inglês | MEDLINE | ID: mdl-34202062

RESUMO

NAND flash memory is widely used in communications, commercial servers, and cloud storage devices with a series of advantages such as high density, low cost, high speed, anti-magnetic, and anti-vibration. However, the reliability is increasingly getting worse while process improvements and technological advancements have brought higher storage densities to NAND flash memory. The degradation of reliability not only reduces the lifetime of the NAND flash memory but also causes the devices to be replaced prematurely based on the nominal value far below the minimum actual value, resulting in a great waste of lifetime. Using machine learning algorithms to accurately predict endurance levels can optimize wear-leveling strategies and warn bad memory blocks, which is of great significance for effectively extending the lifetime of NAND flash memory devices and avoiding serious losses caused by sudden failures. In this work, a multi-class endurance prediction scheme based on the SVM algorithm is proposed, which can predict the remaining P-E cycle level and the raw bit error level after various P-E cycles. Feature analysis based on endurance data is used to determine the basic elements of the model. Based on the error features, we present a variety of targeted optimization strategies, such as extracting the numerical features closely related to the endurance, and reducing the noise interference of transient faults through short-term repeated operations. Besides a high-parallel flash test platform supporting multiple protocols, a feature preprocessing module is constructed based on the ZYNQ-7030 chip. The pipelined module of SVM decision model can complete a single prediction within 37 us.

8.
Sci Adv ; 7(18)2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33931457

RESUMO

During the Mid-Miocene Climatic Optimum [MMCO, ~14 to 17 million years (Ma) ago], global temperatures were similar to predicted temperatures for the coming century. Limited megathermal paleoclimatic and fossil data are known from this period, despite its potential as an analog for future climate conditions. Here, we report a rich middle Miocene rainforest biome, the Zhangpu biota (~14.7 Ma ago), based on material preserved in amber and associated sedimentary rocks from southeastern China. The record shows that the mid-Miocene rainforest reached at least 24.2°N and was more widespread than previously estimated. Our results not only highlight the role of tropical rainforests acting as evolutionary museums for biodiversity at the generic level but also suggest that the MMCO probably strongly shaped the East Asian biota via the northern expansion of the megathermal rainforest biome. The Zhangpu biota provides an ideal snapshot for biodiversity redistribution during global warming.

9.
Ecotoxicol Environ Saf ; 217: 112274, 2021 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-33930771

RESUMO

Canonical ammonia-oxidizing archaea (AOA), ammonia-oxidizing bacteria (AOB) and complete-nitrifying bacteria (comammox) exist in a variety of ecosystems. However, little is known about AOA, AOB and comammox or their contributions to nitrification in the soils of heavily degraded and acidic mine regions. In the present study, the activity, richness, diversity and distribution patterns of AOA, AOB and comammox in the Siding mine area were investigated. Nemerow's multifactor pollution index (PN) values indicated that the soil in all three areas in the Siding mine area was highly contaminated by Cd, Pb, Zn, Mn and Cu. The AOA, AOB and comammox amoA gene copy numbers exhibited significant positive correlations with Pb and Zn levels and PN values, which indicated that the populations of AOA, AOB and comammox underwent adaptation and reproduction in response to pollution from multiple metals in the Siding mine area. Among them, the abundance of AOA was the highest, and AOA may survive better than AOB and comammox under such severely pollution-stressed and ammonia-limited conditions. The phyla Thaumarchaeota and Crenarchaeota may play vital roles in the soil ammonia oxidation process. Unlike AOA, AOB may use soil available phosphorus to help them compete for NH3 and other limiting nutrients with AOA and heterotrophs. Moreover, soil organic matter was the main factor influencing the species diversity of AOB, the ß-diversity of AOB and comammox, and the community composition of AOA, AOB and comammox. Our research will help to explain the role and importance of AOA, AOB and comammox in the different ecological restoration regions in the Siding mine area.


Assuntos
Amônia/metabolismo , Biodegradação Ambiental , Mineração , Microbiologia do Solo , Archaea/metabolismo , Bactérias/metabolismo , Betaproteobacteria/metabolismo , Biodiversidade , Ecossistema , Nitrificação , Oxirredução , Fósforo/metabolismo , Filogenia , Solo , Poluentes do Solo
10.
Sensors (Basel) ; 20(17)2020 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-32872600

RESUMO

The Internet of Things (IoT) is an industry-recognized next intelligent life solution that increases the level of comfort, efficiency, and automation for citizens through numerous sensors, smart devices, and cloud stations connected physically. As an important application scenario of IoT, the Internet of Vehicles (IoV) plays an extremely critical role in the intelligent transportation field. In fact, the In-Vehicle Network of smart vehicles that are recognized as the core roles in intelligent transportation is currently the Controller Area Network (CAN). However, the In-Vehicle CAN bus protocol has several vulnerabilities without any encryption, authentication, or integrity checking, which severely threatens the safety of drivers and passengers. Once malicious attackers hack the vehicular gateway and obtain the access right of the CAN, they may control the vehicle based on the vulnerabilities of the CAN bus protocol. Given the severe security risk of CAN, we proposed the CANsec, a practical In-Vehicle CAN security evaluation tool that simulates malicious attacks according to major attack models to evaluate the security risk of the In-Vehicle CAN. We also show a usage case of the CANsec without knowing any information from the vehicle manufacturer.

11.
Sensors (Basel) ; 20(17)2020 Sep 03.
Artigo em Inglês | MEDLINE | ID: mdl-32899244

RESUMO

The Short-range-controlled communication system (RCC) based on a subscriber identity module (SIM) card is a replacement for the standard near-field communication (NFC) system to support near-field payment applications. The RCC uses both the low-frequency (LF) and high-frequency (HF) wireless communication system. The RCC communication distance is controlled under 10 cm. However, current RCCs suffer from compatibility issues, and the LF communication distance is lower than 0.5 cm in some phones with completely metallic shells. In this paper, we propose an improved LF communication system design, including an LF transmitter circuit, LF receiver chip, and LF-HF communication protocol. The LF receiver chip has a rail-to-rail amplifier and a self-correcting clock recovery differential Manchester decoder, which do not have the limitations of accurate gain and high system clock. The LF receiver chip is fabricated in a 0.18 µm CMOS technology platform, with a die size of 1.05 mm × 0.9 mm and current consumption of 41 µA. The experiments show that the improved RCC has better compatibility, and the communication distance reaches to 4.2 cm in phones with completely metallic shells.

12.
Proc Biol Sci ; 287(1935): 20201661, 2020 09 30.
Artigo em Inglês | MEDLINE | ID: mdl-32933445

RESUMO

The bivalved crustacean ostracods have the richest fossil record of any arthropod group and display complex reproductive strategies contributing to their evolutionary success. Sexual reproduction involving giant sperm, shared by three superfamilies of living ostracod crustaceans, is among the most fascinating behaviours. However, the origin and evolution of this reproductive mechanism has remained largely unexplored because fossil preservation of such features is extremely rare. Here, we report exceptionally preserved ostracods with soft parts (appendages and reproductive organs) in a single piece of mid-Cretaceous Kachin amber (approximately 100 Myr old). The ostracod assemblage is composed of 39 individuals. Thirty-one individuals belong to a new species and genus, Myanmarcypris hui gen. et sp. nov., exhibiting an ontogenetic sequence from juveniles to adults (male and female). Seven individuals are assigned to Thalassocypria sp. (Cypridoidea, Candonidae, Paracypridinae) and one to Sanyuania sp. (Cytheroidea, Loxoconchidae). Our micro-CT reconstruction provides direct evidence of the male clasper, sperm pumps (Zenker organs), hemipenes, eggs and female seminal receptacles with giant sperm. Our results reveal that the reproduction behavioural repertoire, which is associated with considerable morphological adaptations, has remained unchanged over at least 100 million years-a paramount example of evolutionary stasis. These results also double the age of the oldest unequivocal fossil animal sperm. This discovery highlights the capacity of amber to document invertebrate soft parts that are rarely recorded by other depositional environments.


Assuntos
Crustáceos/anatomia & histologia , Genitália Masculina , Espermatozoides , Âmbar , Animais , Artrópodes , Feminino , Fósseis , Genitália , Masculino , Reprodução , Microtomografia por Raio-X
13.
Sci Rep ; 10(1): 10375, 2020 06 25.
Artigo em Inglês | MEDLINE | ID: mdl-32587290

RESUMO

Marine biofouling can cause a biocorrosion, resulting in degradation and failure of materials and structures. In order to prevent sea creatures from attaching to the surface, in this work, a new environmentally friendly antifouling coating by incorporating antibacterial polymers and natural antifouling agents has been designed and synthesized. Surface chemical composition and changes in surface hydrophobicity were studied by FTIR spectroscopy and contact angle measurements, respectively. Measurements of mass loss of antifouling resin were also carried out and the release rate of camphor from antifouling coating was tested by using UPLC. It had been found that the changes in the content of triisopropylsilylacrylate (TIPSA) (from 4% to 12%) and isobornyl methacrylate (IBOMA) (from 50% to 16.7%) did not significantly affect the release of camphor. The content of IBOMA decreased from 50% to 16.7%, the antifouling performance of the resin system appeared slightly reduced. In addition, rosin could help regulate the release rate of the resin system to desorb camphor slowly in water in a controlled manner. Furthermore, the antifouling capability of as-prepared samples was evaluated via algae suppression experiments and marine field tests. This study highlighted the environmentally friendly antifouling coating as a potential candidate and efficient strategy to prohibit biofouling in seawater.

14.
Ultrasonography ; 39(4): 356-366, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32407611

RESUMO

PURPOSE: The purpose of this study was to retrospectively compare the clinical characteristics and imaging features on (CEUS) of combined hepatocellular cholangiocarcinoma (CHC) with those of hepatocellular carcinoma (HCC) and cholangiocarcinoma (CC). METHODS: The clinical information and CEUS features of 45 patients with CHC from 2015 to 2019 and 1-to-1-matched control subjects with HCC and CC (45 each) were compared. RESULTS: Simultaneous elevation of α-fetoprotein (AFP) and cancer antigen (CA) 19-9 was more common in CHC than in HCC and CC. In the arterial phase, hyperenhancement (homogeneous and heterogeneous) was more common in CHC (73.3%) and HCC (100%), while peripheral rimlike enhancement was more common in CC (55.6%). In the portal phase, marked washout was significantly more frequent in CHC and CC than in HCC (42.2% and 53.3% vs. 6.7%). In the delayed phase, marked washout was more common in CHC (82.2%) and CC (93.3%) than in HCC (40.0%). The washout time (WT) was much shorter in CHC and CC than in HCC (33.8±13.1 seconds and 30.1±11.6 seconds vs. 58.4±23.5 seconds). Using the combination of simultaneous elevation of AFP and CA 19-9 with marked washout in the delayed phase and a WT <38 seconds or arterial hyperenhancement to differentiate CHC from HCC or CC, the accuracy, sensitivity, and specificity were 74.4%, 93.3%, and 55.6% and 71.1%, 80.0%, and 62.2%, respectively. CONCLUSION: Although some CEUS imaging features of CHC, HCC, and CC overlap, the combination of tumor markers and CEUS features can be helpful in differentiating CHC from HCC and CC.

15.
Environ Sci Pollut Res Int ; 27(16): 19933-19945, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32232756

RESUMO

Mine tailings are a characteristic of landscapes where mineral extraction has occurred and provide a prime opportunity for vegetation succession. In this study, soil heavy metal concentrations, plant composition and biodiversity, heavy metal accumulation, and their relationships were studied in the tailings of the Pingle Mn mine (abandoned for over 15 years) in South China. The total heavy metal concentrations ranged from 440 to 15,590 mg kg-1 for Mn, 5.01 to 20.7 mg kg-1 for Cd, 101 to 319 mg kg-1 for Pb, 546 to 1693 mg kg-1 for Zn, and 116 to 180 mg kg-1 for Cu. According to soil contamination assessment by single contamination indexes and the Nemerow multifactor index, the tailing soil had a heavy pollution level. According to ecological risk assessment by monomial potential ecological risk factors and potential ecological risk indexes, the tailing soil presented a high ecological risk level, to which Cd was the key contributor. A total of 13 plant species from 2 families (Gramineae and Compositae) successfully colonized the tailings. Importance values based on relative height, relative coverage, relative abundance, and relative frequency indicated that Neyraudia reynaudiana K. and Paspalum orbiculare F. were the dominant species. The species were multi-metal-tolerant species, and most of them were shoot accumulators, as their translocation factor values were above 1. Plants exhibited the highest bioconcentration factor for Pb, and the average values for roots, stems, and leaves were 2.56, 1.45, and 1.70, respectively. There were positive relationships (P < 0.01) between soil Mn, Cd, Zn, and Cu and plant Pb; similar results were found for soil heavy metals and leaf/stem Mn. The species composition in the tailings of the Pingle Mn mine was reflective of long-term vegetation succession, and the results obtained in this study provide insight for selecting plant species and reconstruction practices for Mn wasteland restoration.


Assuntos
Metais Pesados/análise , Poluentes do Solo/análise , China , Monitoramento Ambiental , Manganês , Solo
16.
Sci Adv ; 6(10): eaay1259, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-32181343

RESUMO

Mesozoic long-proboscid scorpionflies (Mesopsychoidea) provide important clues to ancient plant-pollinator interactions. Among them, the family Aneuretopsychidae is especially important because its mouthparts are vital to deciphering the early evolution of Mesopsychoidea and putatively the origin of fleas (Siphonaptera). However, the identification of mouthpart homologs among Aneuretopsychidae remains controversial because of the lack of three-dimensional anatomical data. Here, we report the first Aneuretopsychidae from Late Cretaceous Burmese amber, which have short maxillary palpi and elongate mouthpart elements consisting of one pair of galeae and one hypopharynx. Their mouthparts are identical to those of Pseudopolycentropodidae (= Dualulidae, new synonym) but are not homologous to those of Siphonaptera. Our phylogenetic analysis provides robust evidence for the debated monophyly of Mesopsychoidea. Our results suggest that the long-proboscid condition has most likely evolved once in Mesopsychoidea, independently from fleas, and further reveal the variety and complexity of mid-Cretaceous pollinating insects.


Assuntos
Dípteros/classificação , Especiação Genética , Boca/anatomia & histologia , Filogenia , Escorpiões/classificação , Sifonápteros/classificação , Âmbar , Animais , China , Dípteros/anatomia & histologia , Dípteros/fisiologia , Extinção Biológica , Fósseis/história , História Antiga , Boca/fisiologia , Mianmar , Plantas , Polinização/fisiologia , Escorpiões/anatomia & histologia , Escorpiões/fisiologia , Sifonápteros/anatomia & histologia , Sifonápteros/fisiologia
17.
Proc Natl Acad Sci U S A ; 116(23): 11345-11350, 2019 06 04.
Artigo em Inglês | MEDLINE | ID: mdl-31085633

RESUMO

Amber is fossilized tree resin, and inclusions usually comprise terrestrial and, rarely, aquatic organisms. Marine fossils are extremely rare in Cretaceous and Cenozoic ambers. Here, we report a record of an ammonite with marine gastropods, intertidal isopods, and diverse terrestrial arthropods as syninclusions in mid-Cretaceous Burmese amber. We used X-ray-microcomputed tomography (CT) to obtain high-resolution 3D images of the ammonite, including its sutures, which are diagnostically important for ammonites. The ammonite is a juvenile Puzosia (Bhimaites) and provides supporting evidence for a Late Albian-Early Cenomanian age of the amber. There is a diverse assemblage (at least 40 individuals) of arthropods in this amber sample from both terrestrial and marine habitats, including Isopoda, Acari (mites), Araneae (spiders), Diplopoda (millipedes), and representatives of the insect orders Blattodea (cockroaches), Coleoptera (beetles), Diptera (true flies), and Hymenoptera (wasps). The incomplete preservation and lack of soft body of the ammonite and marine gastropods suggest that they were dead and underwent abrasion on the seashore before entombment. It is most likely that the resin fell to the beach from coastal trees, picking up terrestrial arthropods and beach shells and, exceptionally, surviving the high-energy beach environment to be preserved as amber. Our findings not only represent a record of an ammonite in amber but also provide insights into the taphonomy of amber and the paleoecology of Cretaceous amber forests.


Assuntos
Âmbar/química , Animais , Ecossistema , Florestas , Fósseis , Gastrópodes/química , Resinas Vegetais/química , Árvores/química , Microtomografia por Raio-X/métodos
18.
Chemosphere ; 221: 665-671, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30677727

RESUMO

Nitrogen limitation has been proven to inhibit Microcystis proliferation, and the significant decline in Microcystis blooms in late summer or autumn has been considered to be related to the nitrogen depletion in water. Sinking loss is another factor that influences the dynamics of cyanobacteria in lakes. However, to date, it is still unclear how the sinking property of Microcystis responds to nitrogen availability. Our results suggest that nitrogen limitation would directly influence sinking property of Microcystis, through a significant increase in the specific density of cells. In the short term, carbohydrate accumulation was mainly responsible for the high specific density, showing a high correlation among the NO3--N concentration, specific density and carbohydrate content. Furthermore, carbohydrates could rapidly accumulate after one light/dark cycle, which was mainly due to the reduction in carbohydrate consumption in the darkness under nitrogen limitation. Under nitrogen-light coupling conditions, the specific density ranged from 1.060 to 1.068, except for the treatment with high-nitrogen plus low-light, which showed the value of 1.032. More importantly, when coupled with low nitrogen, the low light did not decrease the carbohydrate content and the specific density, which implied that the sinking cells could not migrate back to the surface. Accordingly, a hypothesis was proposed that the carbohydrate accumulation induced by low nitrogen availability caused an increase in specific density, which invalidates the buoyancy regulation, and cells sink continually out of the water column. This study explores a new understanding on the disappearance mechanisms of Microcystis blooms in the late summer and fall.


Assuntos
Metabolismo dos Carboidratos , Microcystis/fisiologia , Nitrogênio/análise , Estações do Ano , Cianobactérias/fisiologia , Lagos/microbiologia , Gravidade Específica
19.
Sci Adv ; 4(9): eaat1380, 2018 09.
Artigo em Inglês | MEDLINE | ID: mdl-30191177

RESUMO

The Triassic represented an important period that witnessed the diversification of marine and terrestrial ecosystems. The radiations of terrestrial plants and vertebrates during this period have been widely investigated; however, the Triassic history of insects, the most diverse group of organisms on Earth, remains enigmatic because of the rarity of Early-Middle Triassic fossils. We report new insect fossils from a Ladinian deposit (Tongchuan entomofauna) dated to approximately 238 to 237 million years ago and a Carnian deposit (Karamay entomofauna) in northwestern China, including the earliest definite caddisfly cases (Trichoptera), water boatmen (Hemiptera), diverse polyphagan beetles (Coleoptera), and scorpionflies (Mecoptera). The Tongchuan entomofauna is near the Ladinian-Carnian boundary in age, providing a calibration date for correlation to contemporaneous biotas. Our findings confirm that the clade Holometabola, comprising most of the modern-day insect species, experienced extraordinary diversification in the Middle-Late Triassic. Moreover, our results suggest that the diversification of aquatic insects (a key event of the "Mesozoic Lacustrine Revolution") had already begun by the Middle Triassic, providing new insights into the early evolution of freshwater ecosystems.


Assuntos
Evolução Biológica , Fósseis , Insetos/fisiologia , Animais , China , Geologia/métodos , Silicatos , Zircônio
20.
Nat Commun ; 9(1): 3170, 2018 08 09.
Artigo em Inglês | MEDLINE | ID: mdl-30093646

RESUMO

Insect faunas are extremely rare near the latest Cretaceous with a 24-million-year gap spanning from the early Campanian to the early Eocene. Here, we report a unique amber biota from the Upper Cretaceous (uppermost Campanian ~72.1 Ma) of Tilin, central Myanmar. The chemical composition of Tilin amber suggests a tree source among conifers, indicating that gymnosperms were still abundant in the latest Campanian equatorial forests. Eight orders and 12 families of insects have been found in Tilin amber so far, making it the latest known diverse insect assemblage in the Mesozoic. The presence of ants of the extant subfamilies Dolichoderinae and Ponerinae supports that tropical forests were the cradle for the diversification of crown-group ants, and suggests that the turnover from stem groups to crown groups had already begun at ~72.1 Ma. Tilin amber biota fills a critical insect faunal gap and provides a rare insight into the latest Campanian forest ecosystem.


Assuntos
Âmbar , Biota/fisiologia , Florestas , Fósseis , Clima Tropical , Animais , Cromatografia Gasosa-Espectrometria de Massas , Geologia , Insetos , Mianmar , Pirólise
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