Structure, Function, and Regulation of the Kainate Receptor.

Neural communication and modulation are complex processes. Ionotropic glutamate receptors (iGluRs) significantly contribute to mediating the fast-excitatory branch of neurotransmission in the mammalian brain. Kainate receptors (KARs), a subfamily of the iGluRs, act as modulators of the neuronal circuitry by playing important roles at both the post- and presynaptic sites of specific neurons. The functional tetrameric receptors are formed by two different gene families, low agonist affinity (GluK1-GluK3) and high agonist affinity (GluK4-GluK5) subunits. These receptors garnered attention in the past three decades, and since then, much work has been done to understand their localization, interactome, physiological functions, and regulation. Cloning of the receptor subunits (GluK1-GluK5) in the early 1990s led to recombinant expression of kainate receptors in heterologous systems. This facilitated understanding of the functional differences between subunit combinations, splice variants, trafficking, and drug discovery. Structural studies of individual domains and recent full-length homomeric and heteromeric kainate receptors have revealed unique functional mechanisms, which have answered several long-standing questions in the field of kainate receptor biology. In this chapter, we review the current understanding of kainate receptors and associated disorders.

Sea ice variability and trends in the Indian Ocean sector of Antarctica: Interaction with ENSO and SAM.

Antarctic sea ice variability is primarily associated with ocean-atmospheric forcing driven by anomalous conditions over the tropical regions of the Pacific and Indian Oceans. The ice-ocean-atmosphere dynamics in the Indian Ocean Sector (IOS) of Antarctica have been studied using monthly satellite and reanalysis observations over four decades (1979-2019). In this study, we revealed that the annual sea ice extent (SIE) in the IOS increases at a rate of 0.7 ± 0.9% decade-1, with a maximum increase in austral summer (5.9 ± 3.7% decade-1). The wavelet approach was used to determine the variability in IOS sea ice caused by the El Niño/Southern Oscillation (ENSO) and southern annular mode (SAM). The SIE has a significant association with both indices during the summer and autumn. In comparison to ENSO, the sea ice variability associated with SAM is typically seasonal in nature and lacks distinct patterns. The wavelet coherence analysis revealed a relatively weak relationship between ENSO and SAM but a highly significant coherence between climatic indices and SIE. We observed that sea ice in the IOS is influenced significantly by climatic oscillations during their negative SAM/El Niño or positive SAM/La Niña phases. Furthermore, the study demonstrated a substantial impact of climatic disturbances in determining the sea ice variability in the IOS.

Non-syndromic Cleft Lip and Palate Patients of the North Indian Population and the Association of Methylenetetrahydrofolate Reductase Gene.

INTRODUCTION: Cleft lip and palate (CLP) is a common congenital anomaly characterized by incomplete fusion of the lip and/or palate during embryonic development. The etiology of CLP is multifactorial, involving genetics and different environmental factors. The methylenetetrahydrofolate reductase (MTHFR) gene has been proposed as a candidate gene associated with CLP due to its involvement in folate metabolism and DNA methylation processes. However, the association between MTHFR gene variants and CLP in non-syndromic patients in the North Indian population remains unclear. AIM AND OBJECTIVES: This research aimed to see the association between MTHFR gene polymorphisms in non-syndromic patients with CLP in the North Indian population. MATERIALS AND METHOD: A case-control observational design comprised 50 CLP patients (cases) and 50 healthy individuals without CLP (controls). Blood samples were collected from patients visiting two hospitals. Genomic DNA was extracted from collected peripheral blood samples, and the genotyping of MTHFR gene polymorphisms (specifically, C677T) was performed using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis. The allelic and genotypic frequencies of MTHFR gene variants were compared between cases and controls using appropriate statistical tests. RESULT: This research revealed a significant association between MTHFR gene polymorphism and CLP in the North Indian population. The odds for the genotypes reach statistical significance, suggesting that the MTHFR gene variant may play a major role in this population's susceptibility to non-syndromic CLP. CONCLUSION: This study provides evidence for a linkage between the MTHFR gene C677T polymorphism and an increased risk of CLP in non-syndromic patients in the North Indian population. These findings do support the involvement of MTHFR gene variants in the etiology of CLP. In the future, more research is warranted to elucidate the underlying mechanisms linking MTHFR gene variants to CLP and to explore potential gene-environment interactions in this context.

Alignment of an ectopic canine with mini-implant anchorage: a case report.

AIMS: To describe the treatment of an ectopic maxillary left canine and Class II molar relationship in a 12 year-old girl. METHODS: A pendulum appliance was used in a first phase of treatment to distalise the maxillary molars to a Class I molar relationship. In the second phase of treatment, a mini-implant, inserted between the roots of the left maxillary central and lateral incisors, provided anchorage to move an ectopic maxillary left canine into position. RESULTS: The implant remained stable throughout treatment and a maxillary canine - first premolar transposition was corrected. Good overjet and overbite were achieved and have been maintained one year after completion of active treatment.

Spatio-temporal change and variability of Barents-Kara sea ice, in the Arctic: Ocean and atmospheric implications.

The reduction in Arctic sea-ice in recent decades has been a significant indicator of climate change and is related to weather pattern changes across the Arctic regions. In this study, for the period 1979-2018, we addressed the processes controlling the sea-ice cover in the Barents-Kara Sea (BKS). The inter-annual variability of the sea-ice extent (SIE) in BKS was analyzed using passive microwave satellite observations. The ocean-atmospheric forcing variables which including air temperature (AT), sea surface temperature (SST) and outgoing long-wave radiation (OLR) were derived from ERA-Interim reanalysis data. The spatial correlation analysis was performed for the year 2016 and 1998, where sea ice concentration (SIC) in BKS is recorded as a minimum and maximum respectively. The long-term analysis (1979-2018) shows negative trends of the Arctic SIE (-4.7 ± 0.3% decade-1) with the largest decrease in the Barents Sea (-23 ± 2.5% decade-1) and Kara Sea (-7.3 ± 0.9% decade-1). However, the sea-ice decline in the Barents Sea was recorded very high during the winter (-17.6 ± 2.2% decade-1) compared to the Kara Sea (-0.8 ± 0.2% decade-1). Sea-ice cover in the Barents Sea is more likely to recede during the summers -4.1 ± 0.7 x 103 km2yr-1 due to warm inflow of Atlantic waters. Correlation analysis using statistically significant trend values with p-values ≤ 0.01 was performed from 1982 to 2018, the SIC of BKS showing significant negative correlation analyses with SST (-0.75; p-value = 0.01), SAT (-0.84; p-value = 0.00) and OLR (-0.76; p-value = 0.00). In recent years, Atlantic Multi-decadal Oscillation (AMO) index has become positive due to an increase in SST anomalies, while, AMO does not reflect the cooling events in the BKS. During recent Arctic climate change, caused by atmospheric heat transport, the loss of sea-ice at BKS is becoming a major factor. In this study, new perspectives of the complex processes associated with Arctic warming and the declining sea-ice in the BKS region are demonstrated.

Global warming leading to alarming recession of the Arctic sea-ice cover: Insights from remote sensing observations and model reanalysis.

The present study quantifies the magnitude of Arctic sea-ice loss in the boreal summer (July-September), especially in September at different timescales (daily, monthly, annual and decadal). The investigation on the accelerated decline in the Arctic sea-ice was performed using different datasets of passive microwave satellite imagery and model reanalysis. Arctic sea-ice declined rapidly in the boreal summer (-10.2 ± 0.8 %decade-1) during 1979-2018, while, the highest decline in sea-ice extent (SIE) (i.e., 82,300 km2 yr-1/-12.8 ± 1.1 %decade-1) is reported in the month of September. Since late 1979, the SIE recorded the sixth-lowest decline during September 2018 (4.71 million km2). Incidentally, the records of twelve lowest extents in the satellite era occurred in the last twelve years. The loss of SIE and sea-ice concentration (SIC) are attributed to the impacts of land-ocean warming and the northward heat advection into the Arctic Ocean. This has resulted in considerable thinning of sea-ice thickness (SIT) and reduction in the multiyear ice (MYI) for summer 2018. Global and Arctic land-ocean temperatures have increased by ~0.78 °C and ~3.1 °C, respectively, over the past 40 years (1979-2018) while substantial warming rates have been identified in the Arctic Ocean (~3.5 °C in the last 40-year) relative to the Arctic land (~2.8 °C in the last 40-year). The prevailing ocean-atmospheric warming in the Arctic, the SIE, SIC and SIT have reduced, resulting in the decline of the sea-ice volume (SIV) at the rate of -3.0 ± 0.2 (1000 km3 decade-1). Further, it observed that the SIV in September 2018 was three times lower than September 1979. The present study demonstrates the linkages of sea-ice dynamics to ice drifting and accelerated melting due to persistent low pressure, high air-ocean temperatures, supplemented by the coupled ocean-atmospheric forcing.