Anthropogenic eutrophication is known to impair the stability of aboveground net primary productivity (ANPP), but its effects on the stability of belowground (BNPP) and total (TNPP) net primary ...productivity remain poorly understood. Based on a nitrogen and phosphorus addition experiment in a Tibetan alpine grassland, we show that nitrogen addition had little impact on the temporal stability of ANPP, BNPP, and TNPP, whereas phosphorus addition reduced the temporal stability of BNPP and TNPP, but not ANPP. Significant interactive effects of nitrogen and phosphorus addition were observed on the stability of ANPP because of the opposite phosphorus effects under ambient and enriched nitrogen conditions. We found that the stability of TNPP was primarily driven by that of BNPP rather than that of ANPP. The responses of BNPP stability cannot be predicted by those of ANPP stability, as the variations in responses of ANPP and BNPP to enriched nutrient, with ANPP increased while BNPP remained unaffected, resulted in asymmetric responses in their stability. The dynamics of grasses, the most abundant plant functional group, instead of community species diversity, largely contributed to the ANPP stability. Under the enriched nutrient condition, the synchronization of grasses reduced the grass stability, while the latter had a significant but weak negative impact on the BNPP stability. These findings challenge the prevalent view that species diversity regulates the responses of ecosystem stability to nutrient enrichment. Our findings also suggest that the ecological consequences of nutrient enrichment on ecosystem stability cannot be accurately predicted from the responses of aboveground components and highlight the need for a better understanding of the belowground ecosystem dynamics.
Anthropogenic eutrophication is known to impair aboveground stability, but its effects on belowground stability remain poorly understood. Based on a nitrogen and phosphorus addition experiment in a Tibetan alpine grassland, we show that the synchronization of grasses (the most abundant plant functional group) resulted in a reduction in their stability, which, in turn, impaired aboveground stability, but remained a poor predictor of belowground stability responses. It suggests that the ecological consequences of nutrient enrichment on ecosystem stability cannot be accurately predicted from the responses of aboveground components, highlighting the need for a better understanding of the belowground ecosystem dynamics.
•We examined the effects of N and P addition on soil enzymes in an alpine grassland.•N addition had no significant effect on plant growth and microbial activities.•P addition enhanced plant growth ...and suppressed activities of some enzymes.•P addition has the potential to enhance carbon storage in the alpine grassland ecosystem.
Soil nitrogen (N) and phosphorus (P) are common limiting nutrients affecting plant primary productivity in alpine ecosystems due to the low decomposition rate, though anthropogenic activities have greatly increased their inputs into ecosystems. Little is known regarding the effects of increasing N and P availabilities on the functioning of belowground microbial communities. To determine how soil microorganisms respond to N and P addition, we measured plant primary productivity, soil microbial biomass, soil mineral N availability, soil respiration, and the activities of soil extracellular enzymes after two years of N- and P-addition in an alpine grassland ecosystem on the Tibetan Plateau. We observed no significant effect of N addition on plant biomass, soil microbial biomass, soil respiration, or the activities of soil extracellular enzymes. In contrast, P addition increased plant biomass but suppressed the activities of most labile-C-cycling enzymes at 0–10cm of soil depth, although the effects on soil microbial biomass and soil respiration were minor. Moreover, there was no interaction between N and P addition on these variables. Overall, N addition does not appear to exert a significant effect on plant primary productivity and microbial activity, whereas P addition increases plant primary productivity and tends to suppress topsoil microbial activity after two years of nutrient application.
Abstract
Intense grazing may lead to grassland degradation on the Qinghai-Tibetan Plateau, but it is difficult to predict where this will occur and to quantify it. Based on a process-based ecosystem ...model, we define a productivity-based stocking rate threshold that induces extreme grassland degradation to assess whether and where the current grazing activity in the region is sustainable. We find that the current stocking rate is below the threshold in ~80% of grassland areas, but in 55% of these grasslands the stocking rate exceeds half the threshold. According to our model projections, positive effects of climate change including elevated CO
2
can partly offset negative effects of grazing across nearly 70% of grasslands on the Plateau, but only in areas below the stocking rate threshold. Our analysis suggests that stocking rate that does not exceed 60% (within 50% to 70%) of the threshold may balance human demands with grassland protection in the face of climate change.
Circular RNAs are known to regulate the biological processes of hepatocellular carcinoma (HCC), and humans with Down syndrome are at low risk of developing solid tumors due to the amplification of ...several tumor suppressor genes on human chromosome 21 (HSA21). Here, we aimed to investigate the potential role of circRNAs originating from HSA21 in the progression of HCC. CircRNA-sequencing was performed to analyze differentially expressed circRNAs in 4 HCC and peritumor tissues, and circRNAs originating from HSA21 were further analyzed. Circ_0061984 (circPTTG1IP) was chosen for further study because it showed the lowest expression in HCC tissues, and qRT-PCR was used to confirm the expression of circPTTG1IP in HCC patient tissues. The biological function of circPTTG1IP was detected in HCC cells both in vivo and in vitro. Moreover, luciferase reporter assays, circRNA immunoprecipitation, and fluorescence in situ hybridization (FISH) were used to investigate the potential mechanism of circPTTG1IP. Finally, the possible mechanisms of filgotinib in circPTTG1IP-driven HCC were assessed. CircPTTG1IP expression was decreased in HCC compared to peritumoral tissues. Moreover, low circPTTG1IP expression was revealed to be associated with a poor prognosis of HCC patients. Elevation of circPTTG1IP was revealed to inhibit HCC development both in vitro and in vivo. Mechanistically, circPTTG1IP was shown to function as a competing endogenous RNA (ceRNA) of RNF125 by binding miR-16-5p to increase the level of the E3 ubiquitin ligase RNF125, which further ubiquitinated and degraded JAK1 protein. Finally, we demonstrated that administration of filgotinib, a JAK1 inhibitor, restricted HCC progression induced by low circPTTG1IP expression. Thus, we revealed that circPTTG1IP is a novel tumor suppresser circRNA in HCC and that a low circPTTG1IP level promotes HCC development via the miR-16-5p/RNF125/JAK1 axis. Patients with low circPTTG1IP may benefit from filgotinib treatment.
•CircPTTG1IP from HSA21 crucially regulates HCC development via the miR-16-5p-RNF125-JAK1 signaling axis.•CircPTTG1IP downregulation favors the inflammatory environment by inducing macrophage recruitment and M2 polarization.•Filgotinib remodels the tumor microenvironment by inhibiting circPTTG1IP-JAK1 axis, which may benefit patient prognosis.
Different forms of nitrogen (N) are deposited on the Qinghai-Tibetan plateau (QTP), while their differential effects on soil methanotrophs and their activity remain elusive. We constructed microcosms ...amended with different N fertilizers (ammonia, nitrate and urea) using the soils sampled from a swamp meadow on the QTP. The responses of active methanotrophs to different forms of nitrogen were determined by stable isotope probing with 5% 13C-methane. At the early stage of incubation, all N fertilizers, especially urea, suppressed methane oxidation compared with the control. The methane oxidation rate increased during the incubation, suggesting an adaptation and stimulation of some methanotrophs to elevated methane. At the onset of the incubation, the type II methanotrophs Methylocystis were most abundant, but decreased during the incubation and were replaced by the type Ia methanotrophs Methylomonas. Ammonia and urea had similar effects on the methanotroph communities, both characterized by an elevation in the proportion of Methylobacter and more diverse methanotroph communities. Nitrate had less effect on the methanotroph community. Our results uncovered the active methanotrophs responding to different nitrogen forms, and suggested that urea-N might have large effects on methanotroph diversity and activity in swamp meadow soils on the QTP.
Over the last century, anthropogenic activities have increased nitrogen (N) deposition considerably, which significantly affects ecosystem processes and has the potential to induce N saturation in ...the future. The continuous increase in N deposition may cause a non-linear response in soil respiration (Rs), an important component of carbon (C) cycling. However, little is known about N saturation threshold of soil respiration. In this study, we conducted coordinated experiments in four grassland types across northern China with four N addition levels to explore patterns in the Rs saturation threshold. Our results showed that an Rs saturation threshold generally exists in grassland ecosystems in response to N addition gradients. The N saturation threshold of Rs occurred at an average rate of 50 kg N ha⁻¹ yr⁻¹, but varied widely with grassland type; the N saturation threshold occurred at rates of 100, 50, 50, and 25 kg N ha⁻¹ - yr⁻¹ in the alpine meadow, meadow steppe, typical steppe, and desert steppe, respectively. Autotrophic respiration (Ra) and heterotrophic respiration (Rh) responded to N addition gradients differently. Ra increased initially and became saturated at a rate of 50 kg N ha⁻¹ yr⁻¹ and declined thereafter. In contrast, Rh decreased monotonically after N addition. Structural equation models further confirmed that the effects of N addition gradients on Rs were primarily determined by the non-linear response of belowground biomass. Interestingly, the compiled global dataset showed that the N saturation threshold of Rs increased with precipitation and soil moisture. These findings indicate that the stimulating effect of N deposition on Rs and Ra might diminish with increasing N deposition in the future, especially in dry grassland ecosystems.
Endoplasmic reticulum stress (ERS) is involved in the development of abdominal aortic aneurysm (AAA). Since bioactive peptide intermedin (IMD)1-53 protects against AAA formation, here we investigated ...whether IMD1–53 attenuates AAA by inhibiting ERS. AAA model was induced by angiotensin II (AngII) in ApoE KO mouse background. AngII-treated mouse aortas showed increased ERS gene transcription of caspase12, eukaryotic translation initiation factor 2a (eIf2a) and activating transcription factor 4(ATF4).The protein level of ERS marker glucose regulated protein 94(GRP94), ATF4 and C/EBP homologous protein 10(CHOP) was also up-regulated by AngII. Increased ERS levels were accompanied by severe VSMC apoptosis in human AAA aorta. In vivo administration of IMD1-53 greatly reduced AngII-induced AAA and abrogated the activation of ERS. To determine whether IMD inhibited AAA by ameliorating ERS, we used 2 non-selective ERS inhibitors phenyl butyrate (4-PBA) and taurine (TAU). Similar to IMD, PBA, and TAU significantly reduced the incidence of AAA and AAA-related pathological disorders. In vitro, AngII infusion up-regulated CHOP, caspase12 expression and led to VSMC apoptosis. IMD siRNA aggravated the CHOP, caspase12-mediated VSMC apoptosis, which was abolished by ATF4 silencing. IMD infusion promoted the phosphorylation of adenosine 5‘-monophosphate (AMP)-activated protein kinase (AMPK) in aortas in ApoE KO mice, and the AMPK inhibitor compound C abolished the protective effect of IMD on VSMC ERS and apoptosis induced by AngII. In conclusion, IMD may protect against AAA formation by inhibiting ERS via activating AMPK phosphorylation.
Computing-in-memory (CIM) based on SRAM is a promising approach to achieving energy-efficient multiply-and-accumulate (MAC) operations in artificial intelligence (AI) edge devices; however, existing ...SRAM-CIM chips support only DNN inference. The flow of training data requires that CIM arrays perform convolutional computation using transposed weight matrices. This article presents a two-way transpose (TWT) multiply cell with high resistance to process variation and a novel read scheme that uses input-aware zone prediction of maximum partial MAC values to enhance the signal margin for robust readout. A 28-nm 64-kb TWT CIM macro fabricated using foundry-provided compact 6T-SRAM cells achieved <inline-formula> <tex-math notation="LaTeX">T_{\text {AC}} </tex-math></inline-formula> of 3.8-21 ns and energy efficiency of 7-61.1 TOPS/W in performing MAC operations using 2-8-b inputs, 4-8-b weights, and 10-20-b outputs.
► We assessed C storage changes in a Chinese fir chronosequence. ► Over-mature Chinese fir stand sequestered less C both in tree biomass and soils. ► Forest conversion caused a large initial loss and ...a low late gain in SOC. ► Subsoil dominated the total SOC loss following forest conversion. ► Understory vegetations dominated fine root biomass at over-mature stage.
Tree plantations established on the natural forest lands increasingly expand globally but their significance in sequestering atmospheric carbon (C) is rarely examined. We investigated changes of C stocks in Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.) plantations converted from a natural broadleaved forest, based on a typical chronosequence in mountainland of subtropical China, which includes six first-generation Chinese fir stands at different development stages: 2- (recently regenerated), 7- (sapling), 16- (middle-aged), 21- (pre-mature), 40- (mature), and 88-year-old (over-mature), with a natural evergreen broadleaved forest (NF) as a comparison. The tree biomass C pool increased linearly from 2 to 40years old, with no further significant increase from 40 to 88years old. Compared with that in the NF forest, the mineral soil organic C (SOC) pool in Chinese fir plantation was decreased by 38.9% to a minimum at 16years old. The soils reaccumulated C only between 16 and 21years old, and then became neutral to C till to the over-mature stage, attaining an equilibrium SOC pool 30% lower than the pre-harvest level. The contribution of subsoil (below 20cm depth) to total profile SOC loss ranged from 53.2% in the recently regenerated stand to 81.1% in the 16-year-old stand, emphasizing the importance of subsoil for the SOC balance. Both litterfall and fine-root biomass of Chinese fir trees exhibited a decreasing trend during late stand development, while the stand fine-root biomass remained relatively constant due to an increased contribution from understory vegetations. The stagnancy in stand fine-root biomass during late stand development might prevent the accruement of total profile SOC. However, the reduction of tree roots and the increase of understory roots did change the vertical distribution of soil C at the over-mature stage: the surface 0–20cm soils accumulated C while the 20–40cm soils lose C. It is concluded that over-mature tree plantations had a limited role in continuously sequestering C as old-growth unmanaged forests did, and that the SOC pools of tree plantations can be hardly recovered to those of natural forests due to a large initial loss and a low late gain in SOC following tree plantation establishment.
This article presents a novel static random access memory computing-in-memory (SRAM-CIM) structure designed for high-precision multiply-and-accumulate (MAC) operations with high energy efficiency ...(EF), high readout accuracy, and short compute latency. The proposed device employs 1) a time-domain incremental-accumulation (TDIA) scheme to enable high-accumulation MAC operations while maintaining a large signal margin across MAC values (MACVs), 2) a dynamic differential-reference (D2REF) scheme based on software-hardware co-design to reduce read energy consumption, and 3) a low-dMACV-aware recursive time-to-digital converter (LMAR-TDC) for implementation with the D2REF scheme to further suppress readout energy consumption. A 28 nm 1 Mb SRAM-CIM macro fabricated using foundry-provided compact 6T-SRAM cells achieved EF of 39.31 TOPS/W and compute latency of 6.6 ns for 8b-MAC operations with 64 accumulations per cycle and near-full output precision (22b).
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