CO2 balance of boreal, temperate, and tropical forests derived from a global database

Terrestrial ecosystems sequester 2.1 Pg of atmospheric carbon annually. A large amount of the terrestrial sink is realized by forests. However, considerable uncertainties remain regarding the fate of this carbon over both short and long timescales. Relevant data to address these uncertainties are being collected at many sites around the world, but syntheses of these data are still sparse. To facilitate future synthesis activities, we have assembled a comprehensive global database for forest ecosystems, which includes carbon budget variables (fluxes and stocks), ecosystem traits (e.g. leaf area index, age), as well as ancillary site information such as management regime, climate, and soil characteristics. This publicly available database can be used to quantify global, regional or biome‐specific carbon budgets; to re‐examine established relationships; to test emerging hypotheses about ecosystem functioning [e.g. a constant net ecosystem production (NEP) to gross primary production (GPP) ratio]; and as benchmarks for model evaluations. In this paper, we present the first analysis of this database. We discuss the climatic influences on GPP, net primary production (NPP) and NEP and present the CO₂ balances for boreal, temperate, and tropical forest biomes based on micrometeorological, ecophysiological, and biometric flux and inventory estimates. Globally, GPP of forests benefited from higher temperatures and precipitation whereas NPP saturated above either a threshold of 1500 mm precipitation or a mean annual temperature of 10 °C. The global pattern in NEP was insensitive to climate and is hypothesized to be mainly determined by nonclimatic conditions such as successional stage, management, site history, and site disturbance. In all biomes, closing the CO₂ balance required the introduction of substantial biome‐specific closure terms. Nonclosure was taken as an indication that respiratory processes, advection, and non‐CO₂ carbon fluxes are not presently being adequately accounted for.     

IL-1 MODIFIES SYSTEM A TRANSPORT ACTIVITY IN HUMAN RHEUMATOID SYNOVIAL CELLS

Given the importance of interleukin-1 in both rheumatic diseases and the modulation of cell metabolic activities, we studied the action of this cytokine on the neutral amino acid transport A system on rheumatoid synovial cells. In these cells IL-1 (1ng/ml) induced amino transport stimulation from 5min to 5h. This effect was obtained only after a starvation period. No concentration-related effect was found for IL-1-stimulated MeAIB uptake, and the IL-1-mediated MeAIB uptake stimulation is independent of protein synthesis. Neosynthesis or post-translational maturation of protein transport is a prerequisite for obtaining this effect. In conclusion, rheumatoid synovial cells exhibit a higher sensitivity for IL-1 than osteoarthritic ones, probably related to their intense metabolic activity.     

Teaching cases: Pulmonary lymphangitic carcinomatosis as a primary manifestation of colon cancer in a young adult

Abstract: Pulmonary lymphangitic carcinomatosis is a metastatic lung disease characterized by diffuse spread of the tumour to the pulmonary lymphatic system. We describe the case of a 31-year-old woman who initially received a diagnosis of sarcoidosis based on the results of imaging studies. However, results of a transbronchial biopsy led to the diagnosis of pulmonary lymphangitic carcinomatosis from metastatic colon cancer.The case: A 31-year-old woman presented to her primary care provider with a nonproductive cough and shortness of breath, which she had experienced intermittently for 1 month. She had no fever, chills or night sweats. She had type 1 diabetes mellitus and hypertension. The patient had experienced multiple miscarriages and was 1 month post partum. She had a 10-pack-year history of smoking. Her father and maternal grandfather both had colon cancer, which, in her father, had been diagnosed after his death at the age of 45. The patient received a diagnosis of exacerbated chronic obstructive pulmonary disease, which was treated with a short course of corticosteroids and broad-spectrum antibiotics. Her condition did not improve.Two months later, the patient presented to the emergency department with dyspnea. A radiograph of her chest showed interstitial lung disease, thickening of the right paratracheal region and hilar prominence. A computed tomography (CT) scan of her chest revealed extensive paratracheal, subcarinal and para-aortic lymphadenopathy. It also showed diffuse consolidation with a nodular pattern throughout the lungs, particularly in the upper lobes and the lower left lobe. She received a diagnosis of sarcoidosis, which her primary care physician treated with corticosteroids. Her symptoms abated, but less than 1 week later, her condition worsened. Oxygen therapy was started at home.A respirologist saw the patient 6 months after the onset of her symptoms. She still had exertional dyspnea and a nonproductive cough without hemoptysis. She had lost 20 pounds in the 5 months preceding the visit. She had tachypnea and tachycardia, and was normotensive and afebrile. She did not have enlarged lymph nodes, skin changes or peripheral edema.Examinations of the patient''s abdomen and heart sounds were unremarkable. We heard rhonchi and crackles in the base of both lungs. A radiograph of her chest showed diffuse interstitial and septal thickening in both lungs (Figure 1). A CT scan showed large nodular areas, ground-glass opacities and thickened interlobular septa with interstitial lung disease (Figure 2).Open in a separate windowFigure 1: Chest radiograph of a 31-year-old woman showing diffuse interstitial and septal thickening (arrow) in both lungs.Open in a separate windowFigure 2: Computed tomography scan showing nodular thickening of interlobular septa (white arrow), seen as polygonal arcades with thickened and nodular limbs, and ground-glass opacities (black arrows).Results of a transbronchial biopsy showed a moderate to poorly differentiated adenocarcinoma. Immunohistochemical studies of the biopsy specimen showed a pattern of staining consistent with metastatic adenocarcinoma most suggestive of a primary origin in the colon. A colonoscopy showed a mass in her proximal sigmoid colon, and biopsy results confirmed the mass to be a moderately differentiated adenocarcinoma. A bone scan showed multiple tomours in her thorax and lumbar spine.The patient was admitted to hospital for chemotherapy (FOLFOX4, a regimen of oxaliplatin, leucovorin and 5-fluorouracil). She was transferred the next day to the intensive care unit because of worsening respiratory distress, necessitating mechanical ventilation. The chemotherapy was continued; however, the patient died of respiratory failure 11 days after admission to hospital.Pulmonary lymphangitic carcinomatosis occurs in 6%–8% of patients with pulmonary metastases.¹ The spread of tumour cells to the pulmonary lymphatic system or the adjacent interstitial tissue results in thickening of the bronchovascular bundles and septa. Desmoplastic reaction due to proliferation of neoplastic cells, and lymphatic dilation by edema fluid or tumour secretions contribute to this interstitial thickening. Spread of the neoplasm outside the interstitium and lymphatic spaces into the adjacent parenchyma can result in a nodular pattern.² Although virtually any metastatic neoplasm can cause pulmonary lymphangitic carcinomatosis, the common locations of the primary tumour are the breasts, stomach, lungs, pancreas and prostate^1,3 (Open in a separate windowPatients with pulmonary lymphangitic carcinomatosis often present with breathlessness and a nonproductive cough. As with our patient, the onset of pulmonary symptoms may precede diagnosis of the primary tumour; however, the frequency of this presentation is unknown. Although chest radiographs appear normal for 30%–50% of patients with histologically proven disease,² pulmonary lymphangitic carcinomatosis has several characteristic changes that can be observed on radiographs (Box 1). Transbronchial biopsy is required for a definitive diagnosis.Open in a separate windowBox 1Pulmonary lymphangitic carcinomatosis can mimic sarcoidosis radiologically. Nodular thickening and ground-glass attenuation are seen in 30%–60% of patients with sarcoidosis. The nodules in sarcoidosis mainly involve central regions of the middle and upper lobes of the lungs. In contrast, changes usually occur in the lower lobes in pulmonary lymphangitic carcinomatosis. Although imaging studies may suggest sarcoidosis, the diagnosis should be confirmed by biopsy results indicating noncaseating granulomas and by the exclusion of other causes of granulomatous disease. Rapid onset and progression of symptoms, asymmetrically enlarged lymph nodes, predominant disease in the lower lobes of the lungs and lack of response to steroids within 2–4 weeks also should alert clinicians to a diagnosis other than sarcoidosis. Thickening of the interlobular septa and peribronchovascular interstitium without a nodular pattern may be seen in other conditions, such as pulmonary edema and idiopathic pulmonary fibrosis.²Although the diagnosis was delayed for our patient, an earlier diagnosis may not have altered the outcome because of the condition''s extremely poor prognosis in most cases. Less than half of patients with pulmonary lymphangitic carcinomatosis who present with respiratory symptoms survive for 3 months.¹ However, platinum-based chemotherapy has led to transient remissions in some cases.⁴Although our patient did not undergo genetic testing, her young age at presentation and strong family history of colon cancer led to a diagnosis of hereditary nonpolyposis colorectal cancer. This condition accounts for 2%–3% of colorectal cancers and is the most common form of hereditary colorectal cancer.⁵ It is characterized by an early onset, with an average age at diagnosis of about 45 years and the presence of tumours predominantly on the right side of the colon. Patients with this condition are also at increased risk of having more than 1 primary colorectal tumour at the time of diagnosis (synchronous neoplasms) and of having another primary tumour after successful treatment of the index tumour (metachronous carcinoma). Patients with this condition are more likely than others of the same age and sex to experience tumours of the endometrium, small bowel, stomach, renal pelvis ureter and ovaries. Skin lesions, including carcinomas and nonmalignant lesions such as sebaceous adenomas and keratoacanthomas, are also more common among these patients.⁶Our patient had unusual features of pulmonary lymphangitic carcinomatosis, including involvement of the sigmoid colon and metastatis to the lungs and spine without liver involvement. This presentation is seen in only about 9% of rectal cancers.⁷ If hereditary nonpolyposis colorectal cancer is suspected, a biopsy of the tumour and genetic testing should be carried out to identify mutations. Once identified, relatives at high risk for colorectal cancer should be counselled and screened for these mutations. Those who carry the mutations should have a colonoscopy every 2 years starting at age 20–25.⁶Anish Thomas MD Robert Lenox MD Department of Medicine State University of New York Syracuse, New York     

Functional mapping of an oligomeric autotransporter adhesin of Aggregatibacter actinomycetemcomitans

Extracellular matrix protein adhesin A (EmaA) is a 202-kDa nonfimbrial adhesin, which mediates the adhesion of the oral pathogen Aggregatibacter actinomycetemcomitans to collagen. EmaA oligomers form surface antenna-like protrusions consisting of a long helical rod with an ellipsoidal ending. The functional analysis of in-frame emaA deletion mutants has located the collagen binding activity to the amino terminus of the protein corresponding to amino acids 70 to 386. The level of collagen binding of this deletion mutant was comparable to the emaA mutant strain. Transmission electron microscopy studies indicate that the first 330 amino acids of the mature protein form the ellipsoidal ending of the EmaA protrusions, where the activity resides. Amino acid substitution analysis within this sequence has identified a critical amino acid, which is essential for the formation of the ellipsoidal ending and for collagen binding activity.     

河内蔬菜基地冬季主要蔬菜上昆虫群落组成

应越南国家植物保护研究院的邀请 ,受我国科技部的委派 ,我们于 2 0 0 1年 1 1～ 1 2月赴越进行“小菜蛾化学信息素的分离鉴定及应用研究”。河内地处热带 ,光照充足 ,雨量充沛 ,气候湿润 ,郊区拥有数百平方公里的蔬菜基地 ,种植着各式各样的蔬菜 ,长势旺盛 ,所产各类蔬菜主要用于出口 ,但虫害较重。在进行小菜蛾PlutellaxylostellaL .化学信息素研究[1] 的同时 ,我们对主要蔬菜品种上的昆虫群落的组成及优势种昆虫进行了考查和分析。1　材料与方法选取 1 0多种蔬菜作为调查对象 ,每种蔬菜样地面积≥ 6 6 6× 2m2 ,以五点取样法选取 5个样…     

Reduced genetic diversity, increased isolation and multiple introductions of invasive giant hogweed in the western Swiss Alps

The giant hogweed ( Heracleum mantegazzianum ) has successfully invaded 19 European countries as well as parts of North America. It has become a problematic species due to its ability to displace native flora and to cause public health hazards. Applying population genetics to species invasion can help reconstruct invasion history and may promote more efficient management practice. We thus analysed levels of genetic variation and population genetic structure of H. mantegazzianum in an invaded area of the western Swiss Alps as well as in its native range (the Caucasus), using eight nuclear microsatellite loci together with plastid DNA markers and sequences. On both nuclear and plastid genomes, native populations exhibited significantly higher levels of genetic diversity compared to invasive populations, confirming an important founder event during the invasion process. Invasive populations were also significantly more differentiated than native populations. Bayesian clustering analysis identified five clusters in the native range that corresponded to geographically and ecologically separated groups. In the invaded range, 10 clusters occurred. Unlike native populations, invasive clusters were characterized by a mosaic pattern in the landscape, possibly caused by anthropogenic dispersal of the species via roads and direct collection for ornamental purposes. Lastly, our analyses revealed four main divergent groups in the western Swiss Alps, likely as a consequence of multiple independent establishments of H. mantegazzianum .     

Long-term survival despite low genetic diversity in the critically endangered Madagascar fish-eagle

The critically endangered Madagascar fish-eagle ( Haliaeetus vociferoides ) is considered to be one of the rarest birds of prey globally and at significant risk of extinction. In the most recent census, only 222 adult individuals were recorded with an estimated total breeding population of no more than 100–120 pairs. Here, levels of Madagascar fish-eagle population genetic diversity based on 47 microsatellite loci were compared with its sister species, the African fish-eagle ( Haliaeetus vocifer ), and 16 of these loci were also characterized in the white-tailed eagle ( Haliaeetus albicilla ) and the bald eagle ( Haliaeetus leucocephalus ). Overall, extremely low genetic diversity was observed in the Madagascar fish-eagle compared to other surveyed Haliaeetus species. Determining whether this low diversity is the result of a recent bottleneck or a more historic event has important implications for their conservation. Using a Bayesian coalescent-based method, we show that Madagascar fish-eagles have maintained a small effective population size for hundreds to thousands of years and that its low level of neutral genetic diversity is not the result of a recent bottleneck. Therefore, efforts made to prevent Madagascar fish-eagle extinction should place high priority on maintenance of habitat requirements and reducing direct and indirect human persecution. Given the current rate of deforestation in Madagascar, we further recommend that the population be expanded to occupy a larger geographical distribution. This will help the population persist when exposed to stochastic factors (e.g. climate and disease) that may threaten a species consisting of only 200 adult individuals while inhabiting a rapidly changing landscape.