Biomass recovery of coastal young mangrove plantations in Central Thailand

Around one-third of the world's most carbon-rich ecosystems, mangrove forests, have already been destroyed in Thailand owing to coastal development and aquaculture. Improving these degraded areas through mangrove plantations can restore various coastal ecosystem services, including CO2 absorption and protection against wave action. This study examines the biomass of three coastal mangrove plantations (Avicennia alba) of different ages in Samut Prakarn province, Central Thailand. Our aim was to understand the forest biomass recovery during the early stages of development, particularly fine root biomass expansion. In the chronosequence of the mangrove plantations, woody biomass increased by 40% over four years from 79.7 ± 11.2 Mg C ha-1 to 111.7 ± 12.3 Mg C ha-1. Fine root biomass up to a depth of 100 cm was 4.47 ± 0.33 Mg C ha-1, 4.24 ± 0.63 Mg C ha-1, and 6.92 ± 0.32 Mg C ha-1 at 10, 12, and 14 year-old sites, respectively. Remarkably, the fine root biomass of 14-year-old site was significantly higher than those of the younger sites due to increase of the biomass at 15-30 cm and 30-50 cm depths. Our findings reveal that the biomass recovery in developing mangrove plantations exhibit rapid expansion of fine roots in deeper soil layers.

Modification of gene expression and soluble factor secretion in the lateral ventricle choroid plexus: Analysis of the impacts on the neocortical development

The choroid plexus (ChP) is the center of soluble factor secretion into the cerebrospinal fluid in the central nervous system. It is known that various signaling factors secreted from the ChP are involved in the regulation of brain development and homeostasis. Intriguingly, the size of the ChP was prominently expanded in the brains of primates, including humans, suggesting that the expansion of the ChP contributed to mammalian brain evolution, leading to the acquisition of higher intelligence and cognitive functions. To address this hypothesis, we established transgenic (Tg) systems using regulatory elements that direct expression of candidate genes in the ChP. Overexpression of sonic hedgehog (Shh) in the developing ChP led to the expansion of the ChP with greater arborization. Shh produced in the ChP caused an increase in neural stem cells (NSCs) in the neocortical region, leading to the expansion of ventricles, ventricular zone, neocortical surface area, and neocortical surface folding. These findings suggest that the activation of Shh signaling via its enhanced secretion from the developing ChP contributed to the evolution of the neocortex. Furthermore, we found that Shh produced in the ChP enhanced NSC proliferation in the postnatal Tg brain, demonstrating that our Tg system can be used to estimate the effects of candidate factors secreted from the ChP on various aspects of brain morphogenesis and functions.

Organic carbon stock and composition in 3.5-m core mangrove soils (Trat, Thailand)

Mangroves are increasingly recognized as an important component of regional and global carbon cycles especially for their high carbon storage capacity. Global estimation of mangrove soil organic carbon (SOC) storage requires detailed regional studies, but estimates of SOC data in deep soils are currently missing in many countries. Furthermore, little is explored on the molecular composition of mangrove SOC. Here, we assessed the SOC stock in a Trat mangrove forest (Thailand) by collecting deep soils (3.5 m) and analyzed the SOC composition for better understanding its potential sources and influencing factors. The Trat mangrove forest had four times higher SOC stock than has been considered for Thai mangrove forests, with the per-area SOC stock of nearly 1000 Mg C ha^-1 which rivals that of Indo-Pacific mangrove forests. The SOC composition analyzed by C/N ratios and spectroscopic techniques differed by tree species and depth. Compositional data principal component analysis revealed that a biological factor (root abundance) had stronger influences than the soil texture (sand versus clay) on the abundance and composition of mangrove SOC. Although surface soil (~1 m) C density was largely controlled by the recent vegetation, deep soil C density reflected other historical processes. This study contributed to a refined estimate of Thailand mangrove SOC stock and revealed that factors influencing SOC abundance and composition differ by tree species and depth.

Dual activation of Shh and Notch signaling induces dramatic enlargement of neocortical surface area

The expansion of the neocortex represents a characteristic event over the course of mammalian evolution. Gyrencephalic mammals that have the larger brains with many folds (gyri and sulci) seem to have acquired higher intelligence, reflective of the enlargement of the neocortical surface area. In this process, germinal layers containing neural stem cells (NSCs) and neural progenitors expanded in number, leading to an increase in the total number of cortical neurons. In this study, we sought to expand neural stem/progenitor cells and enlarge the neocortical surface area by the dual activation of Shh and Notch signaling in transgenic (Tg) mice, promoting the proliferation of neural stem/progenitor cells by the Shh signaling effector while maintaining the undifferentiated state of NSCs by the Notch signaling effector. In the neocortical region of the Tg embryos, NSCs increased in number, and the ventricles, ventricular zone, and neocortical surface area were dramatically expanded. Furthermore, we observed that folds/wrinkles on the neocortical surface were progressively formed, accompanied by the vascular formation. These findings suggest that Shh and Notch signaling may be key regulators of mammalian brain evolution.

Sonic hedgehog expands neural stem cells in the neocortical region leading to an expanded and wrinkled neocortical surface

An expanded and folded neocortex is characteristic of higher mammals, including humans and other primates. The neocortical surface area was dramatically enlarged during the course of mammalian brain evolution from lissencephalic to gyrencephalic mammals, and this bestowed higher cognitive functions especially to primates, including humans. In this study, we generated transgenic (Tg) mice in which the expression of Sonic hedgehog (Shh) could be controlled in neural stem cells (NSCs) and neural progenitors by using the Tet-on system. Shh overexpression during embryogenesis promoted the symmetric proliferative division of NSCs in the neocortical region, leading to the expansion of lateral ventricles and tangential extension of the ventricular zone. Moreover, Shh-overexpressing Tg mice showed dramatic expansion of the neocortical surface area and exhibited a wrinkled brain when overexpression was commenced at early stages of neural development. These results indicate that Shh is able to increase the neocortical NSCs and contribute to expansion of the neocortex.

Hes1 overexpression leads to expansion of embryonic neural stem cell pool and stem cell reservoir in the postnatal brain

Neural stem cells (NSCs) gradually alter their characteristics during mammalian neocortical development, resulting in the production of various neurons and glial cells, and remain in the postnatal brain as a source of adult neurogenesis. Notch-Hes signaling is a key regulator of stem cell properties in the developing and postnatal brain, and Hes1 is a major effector that strongly inhibits neuronal differentiation and maintains NSCs. To manipulate Hes1 expression levels in NSCs, we generated transgenic (Tg) mice using the Tet-On system. In Hes1-overexpressing Tg mice, NSCs were maintained in both embryonic and postnatal brains, and generation of later-born neurons was prolonged until later stages in the Tg neocortex. Hes1 overexpression inhibited the production of Tbr2⁺ intermediate progenitor cells but instead promoted the generation of basal radial glia-like cells in the subventricular zone (SVZ) at late embryonic stages. Furthermore, Hes1-overexpressing Tg mice exhibited the expansion of NSCs and enhanced neurogenesis in the SVZ of adult brain. These results indicate that Hes1 overexpression expanded the embryonic NSC pool and led to the expansion of the NSC reservoir in the postnatal and adult brain.

Ensuring the effects of climate warming; the sensitivity of controlling factors on soil respiration in Sub-Tropical grassland

Prevailing climate change is expected due to carbon dioxide emission to the atmosphere through soil respiration and perhaps the alteration in the terrestrial carbon cycle. The measurements to establish the effect and sensitivity of soil temperature, soil water content and plant biomass on soil respiration was performed in the sub-tropical grassland located in Central Nepal. Field measurements of soil respiration was conducted by using the closed-chamber method, and soil temperature, soil water content and plant biomass were monitored in the years 2015 and 2016. The soil respiration showed positive significant exponential function which accounted for 74.6% (R2=0.746, p<0.05) of its variation with the soil temperature. The temperature sensitivity of soil respiration, Q10 value obtained was 2.68. Similarly, soil respiration showed a positive significant exponential function that accounted for 37.2% (R2=0.372, p<0.05) of its variation with the soil water content. Remarkable seasonal and monthly variations were observed in soil respiration, soil temperature and soil water content, and the plant biomass as well followed the seasonal trend in variation of the soil respiration. Average soil respiration during measurements period was observed 325.51 mg CO2 m-2 h-1 and the annual soil respiration of the grassland in the years 2015 and 2016 was estimated 592.35 g C m-2 y-1. The study confirmed that soil temperature is the most influential primary factor in controlling soil respiration along with the soil water content and plant biomass. This research indicates that through emissions under the increasing temperature and precipitation, in the changing climate, the sub-tropical grassland could be an additional source of carbon dioxide to the atmosphere that might spur risk for further warming.

TRY plant trait database - enhanced coverage and open access

Plant traits-the morphological, anatomical, physiological, biochemical and phenological characteristics of plants-determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait-based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits-almost complete coverage for 'plant growth form'. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait-environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives.

Hes1 expression in mature neurons in the adult mouse brain is required for normal behaviors

Hes1 regulates the maintenance and proliferation of neural stem/progenitor cells as an essential effector of the Notch signaling pathway. Although Notch signaling is also involved in the functions of mature neurons in learning and memory and in the risk factors for mental disorders such as schizophrenia and bipolar disorder, the in-vivo role of Hes1 in mature neurons remains unknown. Here, we found that Hes1 is expressed by subsets of both excitatory and inhibitory neurons in the adult mouse brain, and that Hes1 expression is induced by neuronal stimulation. Furthermore, inactivation of Hes1 in excitatory neurons resulted in abnormal fear and anxiety behaviors concomitantly with higher neuronal excitability in the amygdala, while inactivation of Hes1 in inhibitory neurons resulted in increased sociability and perseverative tendencies. These results indicated that Hes1 is functionally important for normal behaviors not only in excitatory neurons but also in inhibitory neurons in the adult brain.

Regulation of temporal properties of neural stem cells and transition timing of neurogenesis and gliogenesis during mammalian neocortical development

In the developing mammalian neocortex, neural stem cells (NSCs) gradually alter their characteristics as development proceeds. NSCs initially expand the progenitor pool by symmetric proliferative division and then shift to asymmetric neurogenic division to commence neurogenesis. NSCs sequentially give rise to deep layer neurons first and superficial layer neurons later through mid- to late-embryonic stages, followed by shifting to a gliogenic phase at perinatal stages. The precise mechanisms regulating developmental timing of the transition from symmetric to asymmetric division have not been fully elucidated; however, gradual elongation in cell cycle length and concomitant accumulation of determinants that promote neuronal differentiation may function as a biological clock that regulates the onset of asymmetric neurogenic division. On the other hand, epigenetic regulatory systems have been implicated in the regulation of transition timing of neurogenesis and gliogenesis; the polycomb group (PcG) complex and Hmga genes have been found to govern the developmental timing by modulating chromatin structure during neocortical development. Furthermore, we uncovered several factors and mechanisms underlying the regulation of timing of neocortical neurogenesis and gliogenesis. In this review, we discuss recent findings regarding the mechanisms that govern the temporal properties of NSCs and the precise transition timing during neocortical development.

The proneural bHLH genes Mash1, Math3 and NeuroD are required for pituitary development

Multiple signaling molecules and transcription factors are required for pituitary development. Activator-type bHLH genes Mash1, Math, NeuroD (Neurod) and Neurogenin (Neurog) are well known as key molecules in neural development. Although analyses of targeted mouse mutants have demonstrated involvement of these bHLH genes in pituitary development, studies with single-mutant mice could not elucidate their exact functions, because they cooperatively function and compensate each other. The aim of this study was to elucidate the roles of Mash1, Math3 and NeuroD in pituitary development. Mash1;Math3;NeuroD triple-mutant mice were analyzed by immunohistochemistry and quantitative real-time RT-PCR. Misexpression studies with retroviruses in pituisphere cultures were also performed. The triple-mutant adenohypophysis was morphologically normal, though the lumen of the neurohypophysis remained unclosed. However, in triple-mutant pituitaries, somatotropes, gonadotropes and corticotropes were severely decreased, whereas lactotropes were increased. Misexpression of Mash1 alone with retrovirus could not induce generation of hormonal cells, though Mash1 was involved in differentiation of pituitary progenitor cells. These data suggest that Mash1, Math3 and NeuroD cooperatively control the timing of pituitary progenitor cell differentiation and that they are also required for subtype specification of pituitary hormonal cells. Mash1 is necessary for corticotroph and gonadotroph differentiation, and compensated by Math3 and NeuroD. Math3 is necessary for somatotroph differentiation, and compensated by Mash1 and NeuroD. Neurog2 may compensate Mash1, Math3 and NeuroD during pituitary development. Furthermore, Mash1, Math3 and NeuroD are required for neurohypophysis development. Thus, Mash1, Math3 and NeuroD are required for pituitary development, and compensate each other.

Dynamic control of neural stem cells by bHLH factors

During brain development, neural stem cells change their competency to give sequential rise to neurons and glial cells. Expression of the basic helix-loop-helix (bHLH)-type cell-fate determination factors Ascl1, Olig2, and Hes1 is oscillatory in neural stem cells. Conversely, sustained expression of these factors mediates cell-fate determination. Optogenetic analyses suggest that oscillatory expression regulates maintenance and proliferation of neural stem cells, and that sustained expression induces cell-fate determination. Expression of the Notch ligand Delta-like1 (Dll1), which is controlled by Hes1 and Ascl1, is also oscillatory in neural stem cells. Mathematical modeling showed that if the timing of Dll1 expression is changed, Hes1 oscillations are severely dampened, resulting in impaired maintenance and proliferation of neural stem cells and causing microcephaly. Another bHLH factor, Hes5, also shows oscillatory expression in neural stem cells. Hes5 overexpression and knock-out result in abnormal expression of Hmga1 and Hmga2, which are essential for timing the switching of neural stem-cell competency. These data indicate that oscillatory expression of bHLH factors is important for normal neural stem-cell function in the developing nervous system.

Hes5 regulates the transition timing of neurogenesis and gliogenesis in mammalian neocortical development

During mammalian neocortical development, neural stem/progenitor cells (NSCs) sequentially give rise to deep layer neurons and superficial layer neurons through mid- to late-embryonic stages, shifting to gliogenic phase at perinatal stages. Previously, we found that the Hes genes inhibit neuronal differentiation and maintain NSCs. Here, we generated transgenic mice that overexpress Hes5 in NSCs of the central nervous system, and found that the transition timing from deep to superficial layer neurogenesis was shifted earlier, while gliogenesis precociously occurred in the developing neocortex of Hes5-overexpressing mice. By contrast, the transition from deep to superficial layer neurogenesis and the onset of gliogenesis were delayed in Hes5 knockout (KO) mice. We found that the Hmga genes (Hmga1/2) were downregulated in the neocortical regions of Hes5-overexpressing brain, whereas they were upregulated in the Hes5 KO brain. Furthermore, we found that Hes5 expression led to suppression of Hmga1/2 promoter activity. These results suggest that Hes5 regulates the transition timing between phases for specification of neocortical neurons and between neurogenesis and gliogenesis, accompanied by alteration in the expression levels of Hgma genes, in mammalian neocortical development.

Laparoscopy-Assisted Spleen-Preserving Distal Pancreatectomy for Living-Donor Pancreas Transplantation

BACKGROUND

Living pancreas transplantation plays an important role in the treatment of patients with severe type 1 diabetes. However, pancreatectomy is very invasive for the donor, and less-invasive surgical procedures are needed. Although some reports have described hand-assisted laparoscopic surgery for distal pancreatectomy in living-donor operations, less-invasive laparoscopy-assisted (LA) procedures are expected to increase the donor pool. We herein report the outcomes of four cases of LA spleen-preserving distal pancreatectomy (Warshaw technique [WT]) in living pancreas donors.

PATIENTS AND METHODS

Four living pancreas donors underwent LA-WT at our institution from September 2010 to January 2013. All donors fulfilled the donor criteria established by the Japan Society for Pancreas and Islet Transplantation.

RESULTS

The median donor age was 54 years. Two donors underwent left nephrectomy in addition to LA-WT for simultaneous pancreas-kidney transplantation. The median donor operation time for pancreatectomy was 340.5 minutes. The median pancreas warm ischemic time was 3 minutes. The median donor blood loss was 246 g. All recipients immediately achieved insulin independence. One donor required reoperation because of obstructive ileus resulting from a port-site hernia. Another donor developed a pancreatic fistula (International Study Group of Pancreatic Fistula grade B), which was controlled with conservative management. After a maximum follow-up of 73 months, no clinically relevant adverse events had occurred. These results were comparable with those of previous studies concerning living-donor pancreas transplantation.

CONCLUSION

The LA-WT is a safe and acceptable operation for living-donor pancreas transplantation.

High salinity leads to accumulation of soil organic carbon in mangrove soil

Although mangrove forests are one of the most well-known soil organic carbon (SOC) sinks, the mechanism underlying SOC accumulation is relatively unknown. High net primary production (NPP) along with the typical bottom-heavy biomass allocation and low soil respiration (SR) have been considered to be responsible for SOC accumulation. However, an emerging paradigm postulates that SR is severely underestimated because of the leakage of dissolved inorganic carbon (DIC) in groundwater. Here we propose a simple yet unique mechanism for SOC accumulation in mangrove soils. We conducted sequential extraction of water extractable organic matter (WEOM) from mangrove soils using ultrapure water and artificial seawater, respectively. A sharp increase in humic substances (HS) concentration was observed only in the case of ultrapure water, along with a decline in salinity. Extracted WEOM was colloidal, and ≤70% of it re-precipitated by the addition of artificial seawater. These results strongly suggest that HS is selectively flocculated and maintained in the mangrove soils because of high salinity. Because sea salts are a characteristic of any mangrove forest, high salinity may be one of mechanisms underlying SOC accumulation in mangrove soils.

Prognostic value of tumor-infiltrating lymphocytes differs depending on histological type and smoking habit in completely resected non-small-cell lung cancer

BACKGROUND

T-cell infiltration in tumors has been used as a prognostic tool in non-small-cell lung cancer (NSCLC). However, the influence of smoking habit and histological type on tumor-infiltrating lymphocytes (TILs) in NSCLC remains unclear.

PATIENTS AND METHODS

We evaluated the prognostic significance of TILs (CD4⁺, CD8⁺, CD20⁺, and FOXP3⁺) according to histological type and smoking habit using automatic immunohistochemical staining and cell counting in 218 patients with NSCLC.

RESULTS

In multivariate survival analyses of clinical, pathological, and immunological factors, a high ratio of FOXP3⁺ to CD4⁺ T cells (FOXP3/CD4) [hazard ratio (HR): 4.46, P < 0.01 for overall survival (OS); HR: 1.96, P < 0.05 for recurrence-free survival (RFS)] and a low accumulation of CD20⁺ B cells (HR: 2.45, P = 0.09 for OS; HR: 2.86, P < 0.01 for RFS) were identified as worse prognostic factors in patients with adenocarcinoma (AD). In non-AD, a low number of CD8⁺ T cells were correlated with an unfavorable outcome (HR: 7.69, P < 0.01 for OS; HR: 3.57, P < 0.02 for RFS). Regarding smoking habit in AD, a high FOXP3/CD4 ratio was poorly prognostic with a smoking history (HR: 5.21, P < 0.01 for OS; HR: 2.38, P < 0.03 for RFS), whereas a low accumulation of CD20⁺ B cells (HR: 4.54, P = 0.03 for OS; HR: 2.94, P < 0.01 for RFS) was confirmed as an unfavorable factor in non-smokers with AD.

CONCLUSIONS

A low number of CD8⁺ T cells in non-AD, a high FOXP3/CD4 ratio in smokers with AD, and a low number of CD20⁺ B cells in non-smokers with AD were identified as independent unfavorable prognostic factors in resected NSCLC. Evaluating the influence of histological type and smoking habit on the immunological environment may lead to the establishment of immunological diagnosis and appropriate individualized immunotherapy for NSCLC.

Solitary cardiac metastasis of uterine cervical cancer with antemortem diagnosis: A case report and literature review

Cardiac metastasis of uterine cervical cancer with antemortem diagnosis is extremely rare. Therefore, its landscape epidemiology has not been well elucidated to date. In the present study, a case of solitary cardiac metastasis of uterine cervical cancer diagnosed antemortem is reported, and a review of the currently available literature (which includes 18 cases of cardiac metastasis of uterine cervical cancer) is conducted. In January 2013, a 78-year-old woman with squamous cell carcinoma (SCC) of the uterine cervix (International Federation of Gynecology and Obstetrics stage IIIb) underwent definitive radiotherapy at Gunma University Hospital (Gunma, Japan). Follow-up examination at 5 months after completion of the treatment indicated no evidence of recurrence or metastasis. In April 2014, the patient reported epigastric discomfort and general malaise. Electrocardiogram suggested myocardial dysfunction. Transthoracic echocardiography revealed the presence of a mass occupying the right ventricle and pericardial effusion. Cine magnetic resonance imaging demonstrated a filling defect in the right ventricle, and transcatheter biopsy confirmed SCC. The patient was diagnosed with a solitary cardiac metastasis of uterine cervical cancer. Despite aggressive medical therapy, the patient succumbed to disease 31 days after admission to hospital. A review of the current literature revealed that 84% of cases of cardiac metastasis develop within 2 years of completion of the initial treatment, and that electrocardiogram and echocardiography reveal findings of myocardial dysfunction and the presence of a mass in the right ventricle, respectively. A treatment strategy for cardiac metastasis of uterine cervical cancer has not been standardized thus far, and the prognosis is very poor, as the majority of patients succumbed to disease within 1 year. In summary, the current case and the literature review conducted in the present study suggest that: i) Cardiac metastasis should be included in the differential diagnosis in cases with nonspecific complaints such as epigastric discomfort and general malaise when patients have a history of uterine cervical cancer, particularly within the previous 2 years; and ii) electrocardiogram and echocardiography are convenient and effective modalities for the diagnosis of cardiac metastasis of uterine cervical cancer.

Evaluation of salinity effect on quantitative analysis of aquatic humic substances using nonionic DAX-8 resin

A nonionic macroporous resin, Amberlite(®) XAD-8, or its substitute, Supelite™ DAX-8, is used when isolating or quantifying aquatic humic substances (AHS). However, the effect of salinity on the adsorption behavior of AHS onto the resin is yet to be confirmed, rendering the possibility of salinity-induced changes in the values of quantified amounts or characteristics of AHS obtained from a salty system. To verify the results of quantification and isolation of AHS using the resin in different salinity systems, the effect of salinity on such quantitative analyses of AHS has been examined. It has been concluded that the salinity effect is in general trivial and will not hinder comparison of results regardless of sample solution salinity.

Response of sex ratio to timing of breeding in the small cyprinid Gnathopogon caerulescens

The influence of hatching date on the sex ratio of wild Gnathopogon caerulescens was examined. Cohorts reared from eggs collected in the early and middle parts of the spawning season showed almost balanced sex ratios, with female bias in some cohorts. Cohorts born later in the season mostly displayed male bias, and the mean proportion of males later in the season was significantly higher than in early- and mid-season cohorts. These results indicate that the sex ratio of G. caerulescens changes with the time of breeding, increasing along with the ambient water temperature of the lake.

The Parkinson's Disease-Associated Protein Kinase LRRK2 Modulates Notch Signaling through the Endosomal Pathway

Leucine-rich repeat kinase 2 (LRRK2) is a key molecule in the pathogenesis of familial and idiopathic Parkinson’s disease (PD). We have identified two novel LRRK2-associated proteins, a HECT-type ubiquitin ligase, HERC2, and an adaptor-like protein with six repeated Neuralized domains, NEURL4. LRRK2 binds to NEURL4 and HERC2 via the LRRK2 Ras of complex proteins (ROC) domain and NEURL4, respectively. HERC2 and NEURL4 link LRRK2 to the cellular vesicle transport pathway and Notch signaling, through which the LRRK2 complex promotes the recycling of the Notch ligand Delta-like 1 (Dll1)/Delta (Dl) through the modulation of endosomal trafficking. This process negatively regulates Notch signaling through cis-inhibition by stabilizing Dll1/Dl, which accelerates neural stem cell differentiation and modulates the function and survival of differentiated dopaminergic neurons. These effects are strengthened by the R1441G ROC domain-mutant of LRRK2. These findings suggest that the alteration of Notch signaling in mature neurons is a component of PD etiology linked to LRRK2.

LRRK2 is linked to autosomal dominant late-onset Parkinson’s disease, suggesting that LRRK2 gain-of-function mutations lead to age-dependent degeneration of the midbrain dopaminergic neurons. In this study, we describe two novel LRRK2-associated proteins HERC2 and NEURL4, which are a ubiquitin ligase and an adaptor-like protein, respectively. HERC2 and NEURL4 direct LRRK2 to Notch signaling pathway, in which the LRRK2-NEURL4-HERC2 complex promotes the recycling of the Notch ligand Delta-like 1 (Dll1)/Delta (Dl) through the modulation of endosomal trafficking. As a result, the amounts of Dll1/D1 on the plasma membrane are increased, which affects negatively Notch signaling through cis-inhibition. The effect is enhanced by a Parkinson’s-disease associated mutation of LRRK2. Inhibition of Notch signaling in adult dopaminergic neurons impairs its functions and survival. These findings indicate a possible link between Notch pathway and Parkinson’s disease.

Hes1 and Hes5 are required for differentiation of pituicytes and formation of the neurohypophysis in pituitary development

The pituitary gland is a critical endocrine organ regulating diverse physiological functions, including homeostasis, metabolism, reproduction, and growth. It is composed of two distinct entities: the adenohypophysis, including the anterior and intermediate lobes, and the neurohypophysis known as the posterior lobe. The neurohypophysis is composed of pituicytes (glial cells) and axons projected from hypothalamic neurons. The adenohypophysis derives from Rathke's pouch, whereas the neurohypophysis derives from the infundibulum, an evagination of the ventral diencephalon. Molecular mechanisms of adenohypophysis development are much better understood, but little is known about mechanisms that regulate neurohypophysis development. Hes genes, known as Notch effectors, play a crucial role in specifying cellular fates during the development of various tissues and organs. Here, we report that the ventral diencephalon fails to evaginate resulting in complete loss of the posterior pituitary lobe in Hes1(-/-); Hes5(+/-) mutant embryos. In these mutant mice, progenitor cells are differentiated into neurons at the expense of pituicytes in the ventral diencephalon. In the developing neurohypophysis, the proliferative zone is located at the base of the infundibulum. Thus, Hes1 and Hes5 modulate not only maintenance of progenitor cells but also pituicyte versus neuron fate specification during neurohypophysis development.

Inversely estimating the vertical profile of the soil CO2 production rate in a deciduous broadleaf forest using a particle filtering method

Carbon dioxide (CO₂) efflux from the soil surface, which is a major source of CO₂ from terrestrial ecosystems, represents the total CO₂ production at all soil depths. Although many studies have estimated the vertical profile of the CO₂ production rate, one of the difficulties in estimating the vertical profile is measuring diffusion coefficients of CO₂ at all soil depths in a nondestructive manner. In this study, we estimated the temporal variation in the vertical profile of the CO₂ production rate using a data assimilation method, the particle filtering method, in which the diffusion coefficients of CO₂ were simultaneously estimated. The CO₂ concentrations at several soil depths and CO₂ efflux from the soil surface (only during the snow-free period) were measured at two points in a broadleaf forest in Japan, and the data were assimilated into a simple model including a diffusion equation. We found that there were large variations in the pattern of the vertical profile of the CO₂ production rate between experiment sites: the peak CO₂ production rate was at soil depths around 10 cm during the snow-free period at one site, but the peak was at the soil surface at the other site. Using this method to estimate the CO₂ production rate during snow-cover periods allowed us to estimate CO₂ efflux during that period as well. We estimated that the CO₂ efflux during the snow-cover period (about half the year) accounted for around 13% of the annual CO₂ efflux at this site. Although the method proposed in this study does not ensure the validity of the estimated diffusion coefficients and CO₂ production rates, the method enables us to more closely approach the “actual” values by decreasing the variance of the posterior distribution of the values.

Hbp1 regulates the timing of neuronal differentiation during cortical development by controlling cell cycle progression

In the developing mammalian brain, neural stem cells (NSCs) initially expand the progenitor pool by symmetric divisions. NSCs then shift from symmetric to asymmetric division and commence neurogenesis. Although the precise mechanisms regulating the developmental timing of this transition have not been fully elucidated, gradual elongation in the length of the cell cycle and coinciding accumulation of determinants that promote neuronal differentiation may function as a biological clock that regulates the onset of asymmetric division and neurogenesis. We conducted gene expression profiling of embryonic NSCs in the cortical regions and found that expression of high mobility group box transcription factor 1 (Hbp1) was upregulated during neurogenic stages. Induced conditional knockout mice of Hbp1 generated by crossing with Nestin-CreERT2 mice exhibited a remarkable dilatation of the telencephalic vesicles with a tangentially expanded ventricular zone and a thinner cortical plate containing reduced numbers of neurons. In these Hbp1-deficient mouse embryos, neural stem/progenitor cells continued to divide with a shorter cell cycle length. And downstream target genes of the Wnt signaling, such as cyclin D1 and c-jun, were upregulated in the germinal zone of the cortical regions. These results indicate that Hbp1 plays a critical role in regulating the timing of cortical neurogenesis by elongating the cell cycle and is essential for normal cortical development.

Hes1 and Hes5 regulate vascular remodeling and arterial specification of endothelial cells in brain vascular development

The vascular system is the first organ to form in the developing mammalian embryo. The Notch signaling pathway is an evolutionarily conserved signaling mechanism essential for proper embryonic development in almost all vertebrate organs. The analysis of targeted mouse mutants has demonstrated essential roles of the Notch signaling pathway in embryonic vascular development. However, Notch signaling-deficient mice have so far not been examined in detail in the head region. The bHLH genes Hes1 and Hes5 are essential effectors for Notch signaling, which regulate the maintenance of progenitor cells and the timing of their differentiation in various tissues and organs. Here, we report that endothelial-specific Hes1 and Hes5 mutant embryos exhibited defective vascular remodeling in the brain. In addition, arterial identity of endothelial cells was partially lost in the brain of these mutant mice. These data suggest that Hes1 and Hes5 regulate vascular remodeling and arterial fate specification of endothelial cells in the development of the brain. Hes1 and Hes5 represent critical transducers of Notch signals in brain vascular development.

Accelerating the tempo of the segmentation clock by reducing the number of introns in the Hes7 gene

Periodic somite segmentation is controlled by the cyclic gene Hes7, whose oscillatory expression depends upon negative feedback with a delayed timing. The mechanism that regulates the pace of segmentation remains to be determined, but mathematical modeling has predicted that negative feedback with shorter delays would give rise to dampened but more rapid oscillations. Here, we show that reducing the number of introns within the Hes7 gene shortens the delay and results in a more rapid tempo of both Hes7 oscillation and somite segmentation, increasing the number of somites and vertebrae in the cervical and upper thoracic region. These results suggest that the number of introns is important for the appropriate tempo of oscillatory expression and that Hes7 is a key regulator of the pace of the segmentation clock.

Essential roles of the histone methyltransferase ESET in the epigenetic control of neural progenitor cells during development

In the developing brain, neural progenitor cells switch differentiation competency by changing gene expression profiles that are governed partly by epigenetic control, such as histone modification, although the precise mechanism is unknown. Here we found that ESET (Setdb1), a histone H3 Lys9 (H3K9) methyltransferase, is highly expressed at early stages of mouse brain development but downregulated over time, and that ablation of ESET leads to decreased H3K9 trimethylation and the misregulation of genes, resulting in severe brain defects and early lethality. In the mutant brain, endogenous retrotransposons were derepressed and non-neural gene expression was activated. Furthermore, early neurogenesis was severely impaired, whereas astrocyte formation was enhanced. We conclude that there is an epigenetic role of ESET in the temporal and tissue-specific gene expression that results in proper control of brain development.