Bark structure is coordinated with xylem hydraulic properties in branches of five Cupressaceae species

The properties of bark and xylem contribute to tree growth and survival under drought and other types of stress conditions. However, little is known about the functional coordination of the xylem and bark despite the influence of selection on both structures in response to drought. To this end, we examined relationships between proportions of bark components (i.e. thicknesses of tissues outside the vascular cambium) and xylem transport properties in juvenile branches of five Cupressaceae species, focusing on transport efficiency and safety from hydraulic failure via drought-induced embolism. Both xylem efficiency and safety were correlated with multiple bark traits, suggesting that xylem transport and bark properties are coordinated. Specifically, xylem transport efficiency was greater in species with thicker secondary phloem, greater phloem-to-xylem thickness ratio and phloem-to-xylem cell number ratio. In contrast, species with thicker bark, living cortex and dead bark tissues were more resistant to embolism. Thicker phellem layers were associated with lower embolism resistance. Results of this study point to an important connection between xylem transport efficiency and phloem characteristics, which are shaped by the activity of vascular cambium. The link between bark and embolism resistance affirms the importance of both tissues to drought tolerance.

Influence of Crosslink Density on Electrical Performance and Rheological Properties of Crosslinked Polyethylene

To investigate the influence of the crosslinked polyethylene (XLPE) structure on electrical performance, various analytical methods were employed to study polyethylene structures with different degrees of crosslinking. Dynamic rheological analysis was conducted to determine material shear viscosity, dynamic viscosity, storage modulus (G'), loss modulus (G″), and other rheological parameters. Additionally, the electrical performance of the material was analyzed by studying the phenomenon of space charge accumulation under direct current voltage. The results indicate that with an increasing mass fraction of the crosslinking agent, the crosslink density of crosslinked polyethylene initially increases and then decreases. When the dicumyl peroxide (DCP) content exceeds 1.0 wt.%, there is an accumulation of like-polarity space charges. The best rheological processing performance of crosslinked polyethylene is observed when the DCP content is in the range of 1.0-1.5 wt.%.

Flow-diverter stents in intracranial aneurysm treatment: impact on covered cerebral artery branches

OBJECTIVE

Flow diverter stents (FDSs) have attracted interest for intracranial aneurysm (IA) treatment; however, occlusion of side branches and related complications have been reported. This study aimed to investigate the effects of FDSs in IA management when different branches of intracranial arteries are covered.

MATERIALS AND METHODS

A cross-sectional study was conducted using PUBMED, Embase, Web of Science, and Cochrane databases to include randomized or nonrandomized comparative-designed studies from January 2000 to August 2022 which reported outcomes of occlusion/narrowing of branches after IA treatment using FDSs. The PRISMA guidelines were used for our report. A random-effects meta-analysis was conducted to pool the outcomes, which included incidence rates of occlusion/narrowing of FDS-covered branches, branch occlusion-related symptoms, obliteration of IAs, and ideal clinical outcomes (modified Rankin Scale score ≤2).

RESULTS

The authors identified 57 studies involving 3789 patients with IA managed by FDSs covering different branches. During the median imaging follow-up at 12 months, the IA obliteration rate was satisfactory (>70%) when covering the ophthalmic artery (OA), posterior communicating artery (PComA), anterior choroidal artery (AChoA) or anterior cerebral artery (ACA), but not the middle cerebral artery-M2 segment (MCA-M2; 69.5%; 95% CI: 60.8-77.5%) and posterior inferior cerebellar artery (PICA; 59.1%, 13/22). The overall ideal clinical outcome was observed in 97.4% of patients (95% CI: 95.5-98.9%). Higher rates of occlusion/narrowing of branches were identified when FDSs covered the ACA (66.6%; 95% CI: 45.1-85.3%), PComA (44.3%; 95% CI: 34.2-54.6%), or MCA-M2 (39.2%; 95% CI: 24.5-54.7%); the risks were lower when covering the OA (11.8%; 95% CI: 8.8-15.1%), PICA (6.8%; 95% CI: 1.5-14.5%), and AchoA (0.5%; 95% CI: 0.0-2.9%). The risk of branch occlusion-related complications was low (incidence rate <5%) for each of the six evaluated branches.

CONCLUSIONS

Acceptable outcomes were identified following treatment of IAs when FDSs were placed across each of the six studied cerebral arteries. Treatment decisions regarding FDS placement across branch arteries should be made with the risk of complications from branch occlusion in mind.

Varying the expression pattern of the strigolactone receptor gene DAD2 results in phenotypes distinct from both wild type and knockout mutants

The action of the petunia strigolactone (SL) hormone receptor DAD2 is dependent not only on its interaction with the PhMAX2A and PhD53A proteins, but also on its expression patterns within the plant. Previously, in a yeast-2-hybrid system, we showed that a series of a single and double amino acid mutants of DAD2 had altered interactions with these binding partners. In this study, we tested the mutants in two plant systems, Arabidopsis and petunia. Testing in Arabidopsis was enabled by creating a CRISPR-Cas9 knockout mutant of the Arabidopsis strigolactone receptor (AtD14). We produced SL receptor activity in both systems using wild type and mutant genes; however, the mutants had functions largely indistinguishable from those of the wild type. The expression of the wild type DAD2 from the CaMV 35S promoter in dad2 petunia produced plants neither quite like the dad2 mutant nor the V26 wild type. These plants had greater height and leaf size although branch number and the plant shape remained more like those of the mutant. These traits may be valuable in the context of a restricted area growing system such as controlled environment agriculture.

Knotwood and Branchwood Polyphenolic Extractives of Silver Fir, Spruce and Douglas Fir and Their Antioxidant, Antifungal and Antibacterial Properties

The extractive contents of three softwood species largely used in the wood industry, namely Abies alba (Silver fir), Picea abies (spruce) and Pseudotsuga menziesii (Douglas fir), have been determined quantitatively for knots and at different points chosen along their branches, before analysis using high-performance liquid chromatography coupled with Mass Spectrometry (HPLC-MS). The results indicated that branchwood samples located in close proximity to the stem present high contents of extractives similar to those recorded for the knots. HPLC analysis showed quite similar chemical compositions, indicating that first cm of the branches could be considered as an additional source of knotwood. The antibacterial, antifungal and antioxidant activities of knot's extractives have been investigated with the dual objective of better understanding the role of high levels of secondary metabolites present in the knot and evaluating their potential for biorefinery applications. The antioxidant activity study showed that crude extracts of Douglas fir knotwood presented higher radical scavenging activity levels than the extracts of Silver fir and spruce, which presented more or less the same activities. Silver fir and spruce knotwood extracts presented higher antibacterial activity levels than the Douglas fir knotwood extracts did, while Douglas fir knotwood extracts presented more fungal growth inhibition than the spruce and fir knotwood extracts did. The structure-activity relationships indicate that radical scavenging and antifungal activities are associated with a higher relative quantity of flavonoids in the crude extracts, while higher relative quantities of lignans are associated with antibacterial activity.

Incidence and Prognostic Associations of Early Postoperative Stroke and Death Among Patients Undergoing Inner Branched Thoracic Endovascular Repair of Aortic Arch Pathologies: A Systematic Review and Meta-Analysis

OBJECTIVE

The objective of this systematic review was to assess the incidences and associations of early postoperative stroke and death among patients undergoing inner branched thoracic endovascular aortic repair (TEVAR) of arch pathologies.

METHODS

Electronic bibliographic sources (PUBMED, EMBASE, and CENTRAL) were searched up to February 2022 using a combination of thesaurus and free-text terms to identify the studies using branched TEVAR to treat aortic arch disease. The systematic review was conducted according to the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines. All observational studies investigating the prognosis of inner branched TEVAR in the treatment of aortic arch pathologies were included. Independent extraction of articles was performed by two authors using predefined data fields, including study quality indications. All pooled analyses were based on a random-effects or fixed model according to the heterogeneity.

RESULTS

A total of 23 case series totaling 532 participants were included after screening. After optimized selection (largest sample size, most detailed data, lowest risk of bias) from the overlapping data, 12 studies with 289 participants were included in data synthesis. The pooled incidence of 30-day postoperative stroke was 10.6% (95% CI 7.0%-14.2%; p=.41, I²=3%). Pooled 30-day mortality was 4.9% (95% CI 2.0%-7.8%; p=.38, I²=7%). Combined early stroke/death was 15.7% (95% CI 11.2%-20.3%; p=.30, I²=15%). Subgroup analyses of 11 studies (without data missing) showed that a higher incidence of 30-day postoperative stroke was found in studies with aged participants (age≥71.3 years, p=.010), the higher percentage of COPD (≥30%, p= .011) and non-dissection-related pathologies (≥60.8%, p=.011). The higher 30-day postoperative mortality was found in studies with a high percentage of previous coronary artery disease (≥34.5%, p=.023).

CONCLUSIONS

This review demonstrated that there were acceptable rates of 30-day postoperative stroke and death among patients undergoing inner branched TEVAR. It is strongly necessary to perform a rigorous risk assessment of aortic plaque embolism and coronary artery disease when the surgical plan of the inner branched TEVAR is determined.

CLINICAL IMPACT

Treatment arch pathologies with inner branched TEVAR provides acceptable early stroke rate and mortality. Aortic pathology mainly influenced the early stroke rate, and early recognizing high-risk patients for aortic plaque embolism is of supreme importance for reducing the early stroke rate. In addition, the history of coronary artery disease was strongly associated with early mortality, and attention should be paid to the coronary artery assessment and perioperative management of these patients.

The Effect of Dwarfing Interstocks on Vegetative Growth, Fruit Quality and Ionome Nutrition of 'Fuji' Apple Cultivar 'Tianhong 2'-A One-Year Study

Dwarfing interstocks play an essential role in determining the performance of fruit trees. SH40, Jizhen 1, and Jizhen 2 are widely used dwarfing interstocks in Hebei Province, China. This study examined the influence of these three dwarfing interstocks on vegetative growth, fruit quality and yield, and leaf and fruit macro- (N, P, K, Ca, and Mg) and micro- (Fe, Zn, Cu, Mn, and B) element contents for 'Tianhong 2'. Five-year-old 'Fuji' apple cultivar, 'Tianhong 2', on 'Malus. Robusta' rootstock, was cultivated with SH40, Jizhen 1, or Jizhen2 dwarfing rootstock as an interstock bridge. Jizhen 1 and 2 had more branches and a higher proportion of short branches than SH40. Jizhen 2 had a higher yield, good fruit quality, and higher leaf macro- (N, P, K, and Ca) and micro-element (Fe, Zn, Cu, Mn, and B) contents; Jizhen 1 had the highest leaf Mg content in the growing period. The fruit N, P, K, Fe, Zn, Cu, Mn, and B contents were higher in Jizhen 2. SH40 had the highest fruit Ca content. There were significant correlations in nutrient elements between leaves and fruit in June and July. Comprehensive analysis showed that Tianhong 2 had moderate tree vigor, high yield, good fruit quality, and high mineral element content in leaves and fruits when Jizhen 2 was used as an interstock.

Transaxillary Branch-to-Branch-to-Branch Carotid Catheterization Technique for Triple-Branch Arch Repair

PURPOSE

To describe the transaxillary branch-to-branch-to-branch carotid catheterization technique (tranaxillary 3BRA-CCE IT) for cannulation of all supra-aortic vessels using only 1 femoral and 1 axillary access during triple-branch arch repair.

TECHNIQUE

After deployment of the triple-branch arch device, catheterization and bridging of the innominate artery (IA) should be performed through a right axillary access (cutdown or percutaneous). Then, the retrograde left subclavian (LSA) branch should be catheterized (if not preloaded) from a percutaneous femoral access, and a 12×90Fr sheath should be advanced to the outside of the endograft. Subsequently, catheterization of the left common carotid artery (LCCA) antegrade branch should be performed, followed by snaring of a wire in the ascending aorta which was inserted through the axillary access, creating a branch-to-branch-to-branch through-and-through guidewire. Over the axillary access, a 12×45Fr sheath should be inserted into the IA branch and looped in the ascending aorta using a push-and-pull technique so that it faces the LCCA branch, allowing for stable catheterization of the LCCA. The retrograde LSA branch should then be bridged following the standard fashion.

CONCLUSIONS

This series of 5 patients demonstrates that triple-branch arch repair can be performed with the transaxillary 3BRA-CCE IT, allowing catheterization of the supra-aortic vessels without manipulation of the carotid arteries.

CLINICAL IMPACT

The transaxillary 3BRA-CCE IT allows catheterization and bridging of all supra-aortic vessels in triple-branch arch repair through only 2 vascular access points, the femoral artery and the right axillary artery. This technique avoids carotid surgical cutdown and manipulation during these procedures, reducing the risk of access site complications, including bleeding and reintervention, reintubation, cranial nerve lesions, increased operating time, and so on, and has the potential to change the current vascular access standard used during triple-branch arch repair.

Jasmonic acid negatively regulates branch growth in pear

The quality of seedlings is an important factor for development of the pear industry. A strong seedling with few branches and suitable internodes is ideal material as a rootstock for grafting and breeding. Several branching mutants of pear rootstocks were identified previously. In the present study, 'QAU-D03' (Pyrus communis L.) and it's mutants were used to explore the mechanism that affects branch formation by conducting phenotypic trait assessment, hormone content analysis, and transcriptome analysis. The mutant plant (MP) showed fewer branches, shorter 1-year-old shoots, and longer petiole length, compared to original plants (OP), i.e., wild type. Endogenous hormone analysis revealed that auxin, cytokinin, and jasmonic acid contents in the stem tips of MP were significantly higher than those of the original plants. In particular, the jasmonic acid content of the MP was 1.8 times higher than that of the original plants. Transcriptome analysis revealed that PcCOI1, which is a transcriptional regulatory gene downstream of the jasmonic acid signaling pathway, was expressed more highly in the MP than in the original plants, whereas the expression levels of PcJAZ and PcMYC were reduced in the MP compared with that of the original plants. In response to treatment with exogenous methyl jasmonate, the original plants phenotype was consistent with that of the MP in developing less branches. These results indicate that jasmonic acid negatively regulates branch growth of pear trees and that jasmonic acid downstream regulatory genes play a crucial role in regulating branching.

Ontogeny and anatomy of Bouteloua (Poaceae: Chloridoideae) species display a basipetal branch formation and a novel modified leaf structure in grasses

BACKGROUND AND AIMS

Shoot ontogenesis in grasses follows a transition from a vegetative phase into a reproductive phase. Current studies provide insight into how branch and spikelet formation occur during the reproductive phase. However, these studies do not explain all the complex diversity of grass inflorescence forms and are mostly focused on model grasses. Moreover, truncated inflorescences of the non-model grass genus Urochloa (Panicoideae) with formation of primary branches have basipetal initiation of branches. Bouteloua species (Chloridoideae) are non-model grasses that form truncated inflorescences of primary branches with apical vestiges of uncertain homology at the tips of branching events and sterile florets above the lowermost fertile floret. Sterile florets are reduced to rudimentary lemmas composed of three large awns diverging from an awn column. Conflict about the awn column identity of this rudimentary lemma is often addressed in species descriptions of this genus. We test if Bouteloua species can display basipetal initiation of branches and explore the identity of vestiges and the awn column of rudimentary lemmas.

METHODS

We surveyed the inflorescence ontogeny and branch/awn anatomy of Bouteloua species and compared results with recent ontogenetic studies of chloridoids.

KEY RESULTS

Bouteloua arizonica has florets with basipetal maturation. Branches display basipetal branch initiation and maturation. Branch vestiges are formed laterally by meristems during early branching events. The spikelet meristem forms the awn column of rudimentary lemmas. Vestiges and sterile floret awns have anatomical similarities to C4 leaves.

CONCLUSIONS

Basipetal initiation of branches is a novel feature for Chloridoideae grasses. Branch vestiges are novel vegetative grass structures. Sterile floret awn columns are likely to be extensions of the rachilla.

Fenestrated-branched endovascular repair for distal thoraco-abdominal aortic pathology after total aortic arch replacement with frozen elephant trunk

OBJECTIVE

To report the outcomes of fenestrated-branched endovascular repair (FBEVAR) for thoracoabdominal aortic pathology after total aortic arch replacement with frozen elephant trunk (TAR+FET).

METHODS

Interrogation of prospectively-maintained databases from four high volume aortic centres identified consecutive patients treated with distal FBEVAR after prior TAR+FET between August 2013 and September 2020. Primary endpoint was 30-day/in-hospital mortality. Secondary end points were technical success, early clinical success, mid-term survival and freedom from re-intervention. Data are presented as median (IQR).

RESULTS

39 patients [21 men; median age, 73 years (67-75)] with degenerative (n=22) and post-dissection TAAAs (n=17) [median diameter 71 mm (61-78)] were identified. Distal FBEVAR was intended in 27 patients [median interval 9.8 months (6.2-16.6)], anticipated in seven and unexpected in five. 31 patients had a two (n=24) or three (n=7) stage distal FBEVAR. Reno-visceral target vessel preservation was 99.3% (145 of 146). Early primary and secondary technical success was 92% and 97%, respectively. 30-day mortality was 2.6% [n=1; respiratory failure and spinal cord ischaemia (SCI)]. Six survivors also developed SCI which was associated with complete (n=4), or partial recovery (n=2) at hospital discharge. No patients required renal replacement therapy or suffered a stroke. Early clinical success was 95%. Median follow-up was 30.5 months (23.7-49.7). Eleven patients required 16 late re-interventions. Estimated 3-year survival and freedom from re-intervention were 84±6% and 63±10%, respectively.

CONCLUSIONS

Distal FBEVAR after prior TAR+FET is associated with high technical success and low early mortality. The risk of SCI is significant although the majority of patients demonstrate full or partial recovery before hospital discharge. Mid-term patient survival is favourable but there remains a high requirement for late re-intervention. FBEVAR represents an acceptable alternative to distal open TAAA repair.

Risk factors in central retinal vein occlusion: A multi-center case-control study conducted on the Italian population : Demographic, environmental, systemic, and ocular factors that increase the risk for major thrombotic events in the retinal venous system

PURPOSE

To explore the risk factors for central retinal vein occlusion (CRVO) by comparing a large sample of patients with healthy controls.

MATERIALS AND METHODS

Multi-center case-control study. The study group includes patients affected by central retinal vein occlusion, confirmed angiographically, aged 50 years old or above (Group A). The control group includes healthy subjects without an history of retinal vein occlusion (Group B). Outcome measures: age, gender, active smoking, presence of uncontrolled arterial hypertension (uHTN), presence of the following comorbidities: diabetes mellitus type II (DMII), chronic liver disease (CLD), chronic kidney disease (CKD), thyroid disease (TD), systemic lupus erythematosus (SLE), hyperhomocystenemia (HHcy), dyslipidemia (DLip), carotid artery disease (CAD), glaucoma, atrial fibrillation (AF), migraine headache (MH), chronic obstructive pulmonary disease (COPD), obstructive sleep apnea syndrome (OSAS), history of myocardial infarction (MI). Odds-ratios were calculated with logistic regression analysis.

RESULTS

A total of 203 patients (Group A) and 339 controls (Group B). Statistically-significant differences were found for the following variables: age (OR: 1.109 [1.081-1.138], p < .001), active smoking (OR: 2.048 [1.210- 3.466], p < .008), DMII (OR: 4.533 [2.097-9.803], p < .001), HHcy (OR: 4.507 [2.477-10.001 ], p < .001), DLip (OR: 2.255 [1.352-3.762], p  =  .002), CAD (OR: 6.632 [2.944- 14.942], p < .001), glaucoma (OR: 4.656 [2.031-10.673], < .001), OSAS (OR: 1.744 [1.023-2.975], < .041), uHTN (OR: 3.656 [2.247-5.949], < .001). No statistically-significant differences were found for the other variables.

CONCLUSIONS

Older age, active smoking, as well as presence of DMII, HHcy, DLip, CAD, glaucoma, OSAS, and uHTN, all increase the risk for CRVO. A comprehensive assessment of patients with CRVO is paramount. Adequate control of all the aforementioned risk factors is likely of great significance in reducing the incidence of CRVO among the general population, and it likely plays an important role in improving the prognosis following the occlusive event.

Intracranial Hemorrhage After Endovascular Repair of Thoracoabdominal Aortic Aneurysm

BACKGROUND

Intracranial hemorrhage (ICH) is a rare but devastating complication of thoracoabdominal aortic aneurysm (TAAA) repair with fenestrated/branched endograft (f/bEVAR). The cerebrospinal fluid drainage (CSFD) is considered one of the leading causes; however, other possible concomitant factors have not been individualized yet. The aim of the present work was to evaluate the pattern of ICH events after f/bEVAR for TAAA and to identify possible associated factors.

MATERIALS AND METHODS

All f/bEVAR procedures for TAAA performed in a single academic center from 2012 to 2020 were evaluated. ICH was assessed by cerebral computed tomography if neurological symptoms arose. Pre-, intra-, and postoperative characteristics were analyzed in order to identify possible factors associated.

RESULTS

A total of 135 f/bEVAR were performed for 72 (53%) type I, II, III and 63 (47%) type IV TAAA; 74 (55%) were staged procedures, 101 (73%) required CSFD, and 24 (18%) were performed urgently. The overall 30-day mortality was 8% (5% in elective cases); spinal-cord ischemia occurred in 11(8%) and ICH in 8 (6%) patients. All ICH occurred in patients with CSFD. ICH occurred intraoperatively in 1 case, inter-stage in 4 and after F/BEVAR completion in 3, after a median of 6 days the completion stage. Three (38%) of 8 patients with ICH died at 30 days and ICH was associated with 30-day mortality: odds ratio (OR) 13.2, 95% confidence interval (CI): 2.3-76, p=0.01. The analysis of the perioperative characteristics identified platelet reduction >60% (OR 11, 95% CI 1.6-77, p=0.03), chronic kidney disease (16% vs 0%, p=0.002), and total volume of liquor drained >50 mL (OR 8.1, 95% CI 1.1-69, p=0.03) as associated with ICH.

CONCLUSIONS

Current findings may suggest that ICH is a potential lethal complication of the endovascular treatment for TAAAs and it mainly occurs in patients with CSFD. High-volume liquor drainage, platelet reduction, and chronic kidney disease seems increase significantly the risk of ICH and should be considered during the perioperative period and for further studies.

CENTRORADIALIS maintains shoot meristem indeterminacy by antagonizing THORN IDENTITY1 in Citrus

Differential regulation of stem cell activity in shoot meristems contributes to the wide variation in shoot architecture.^1-3 In most Citrus species, a thorn meristem and a dormant axillary meristem co-localize at each leaf base, offset from each other in a spiral phyllotactic pattern. We recently identified THORN IDENTITY1 (TI1) and THORN IDENTITY2 (TI2), encoding TEOSINTE BRANCHED1/CYCLOIDEA/PCF (TCP) transcription factors, as necessary for the termination of meristem proliferation and concomitant thorn production in Citrus.⁴ However, how the dormant axillary meristem at the same leaf axil maintains stem cell activity is still unknown. The phosphatidylethanolamine-binding protein (PEBP)-type transcription factors CENTRORADIALIS (CEN) and TERMINAL FLOWER1 (TFL1) maintain inflorescence meristem indeterminacy in many plant species by antagonizing floral meristem identity regulators.^5-9 Here, we show that, in Citrus, Citrus CEN (CsCEN) maintains vegetative axillary meristem indeterminacy by antagonizing TI1. CsCEN is expressed in the axillary meristem, but not in the thorn meristem. Disruption of CsCEN function results in termination of the stem cell activity and conversion of dormant axillary meristems into thorns, although ectopic overexpression of CsCEN represses TI1 expression and converts thorns into dormant buds, a phenotype similar to the ti1 mutant. We further show that CsCEN interacts with Citrus FD (CsFD) to repress TI1 expression. CsCEN activity depends on the function of TI1 and TI2, as mutations in TI1 and TI2 rescue the cscen mutant phenotype. We suggest that the antagonistic roles of CsCEN and TI1 define the pattern of axillary meristem determinacy, which shapes vegetative Citrus tree shoot architecture.

The assessment of the frequency and arrangement of the subsegmental branches of V3 using computed tomography angiography

Background

The frequency and arrangement of the subsegmental branches of the third portion of the vertebral artery (V3) have been assessed in small samples by autopsy, but they have not been assessed by computed tomography angiography (CTA). To determine the frequency and arrangement of subsegmental branches of V3 by CTA and to analyze the interrelationships among frequency, arrangement, sex, and side-to-side.

Methods

First, the radiology records of 668 consecutive patients who underwent cervical or craniocervical CTA scans from October 1, 2017 to October 31, 2019 were retrospectively retrieved. Second, the four demarcation points were ascertained to define the three subsegments by reviewing the resource images, namely, the vertical portion of V3(V3v), horizontal portion of V3(V3h), and extradural portion of V3(V3e). Then, the numerical value and the location of the bifurcating branch in each subsegment of V3 were recorded. Third, the frequency and arrangement of the branches was assessed, and the relationships between sex, laterality and frequency and arrangement were analyzed as well as the interobserver performance.

Results

On the left, 25%, 20.21%, and 6.59% were the frequencies of one branch in the V3v, V3h, and V3e, and 1.05%, 0.00%, and 0.45% were the frequencies of two branches, respectively. On the right, 25.04%, 17.07%, and 6.44% were the frequencies of one branch in the V3v, V3h, and V3e, and 1.04%, 0.3%, and 0.15% were the frequencies of two branches, respectively. There were no differences between the side-to-side and numerical values of the branches according to the t-test (P=0.4341, P=0.7968), and there were no differences between the side-to-side variable, sex variable and number of branches according to the t-test (P=0.4474, P=0.3593). There were no differences between the side-to-side and eight arrangements (permutation of 000; 100; 110; 111; 010; 011; 001; 101) by using the two-sample KS test (P=0.942), and there were no differences between sex and the eight arrangements according to the two-sample KS test (P=0.9973, P=0.8519). The interobserver reliability was excellent (Spearman's ranked correlation: 0.9927).

Conclusions

The frequency and arrangement of V3 subsegmental branches could be displayed by source imaging with CTA, and there were no significant differences according to the sex or side of the individual. It was imperative to acquaint the subsegmental branches before the operation involving V3 in the craniocervical junction to determine the surgical approach and reduce bleeding during the surgical procedures.

[Physiological response of Xinjiang wild walnut germplasm to low temperature stress]

We examined the physiological response of 1-year-old branches of 37 Xinjiang wild walnut germplasm resources in Gongliu wild walnut forest under cold temperatures (-20 ℃ and 4 ℃) for 12 hours, compared the responses with that of Juglans mandshurica. The relative conductivity (REC), free proline (PRO), soluble sugar (SS), malondialdehyde (MDA) content and peroxidase (POD) activity were measured in an artificial climate chamber by simulating spring low temperature. Subordinate function and principal component analysis were used to evaluate the physiological response of walnut germplasm to low temperature. The results showed that the REC, PRO, SS, MDA content and POD activity of Xinjiang wild walnut were increased. By evaluating the relationship between low temperature resistance and habitat, we found that cold tolerance level was middle valley &gt; east valley &gt; west valley &gt; general valley. Xinjiang wild walnut showed stronger cold tolerance than J. mandshurica. Seven germplasm with cold resistance were selected from the total 37 wild walnut germplasm in Xinjiang, which provided a reference for improving walnut varieties and their responses to sudden weather change in late spring and other growing stages.

Anatomic variations of the Uterine Artery. Review of the literature and their clinical significance

Uterine arteries are the main vessels supplying blood to the uterus. Mainly, they originate from the anterior trunk of the internal iliac artery. Uterine arteries play an important role in pregnancy as well as transcatheter arterial embolization for postpartum hemorrhage and uterine fibroid management. This is a review of the English literature in the PubMed database of the anatomic variety on the origin of uterine arteries and their clinical significance. Eleven studies describe the origin of the uterine arteries and their variations in the literature. In six studies, the uterine artery emerged from internal iliac artery in the majority of the cases, either as a separate branch, or as a bifurcation with the inferior gluteal artery, or trifurcation with superior and inferior gluteal artery. In two studies, the inferior gluteal artery manifested as the main source of the uterine artery, whereas in three studies, the umbilical artery posed as its main origin. Internal iliac artery is described as the most common vascular origin of uterine artery. However, this review highlights that the main vessels of origin for uterine arteries are internal iliac, umbilical and inferior gluteal artery. Nevertheless, classification and further research for this peculiar anatomic structure is fundamental in the future.

Expression of a NGATHA1 Gene from Medicago truncatula Delays Flowering Time and Enhances Stress Tolerance

Shoot branching is one of the most variable determinants of crop yield, and the signaling pathways of plant branches have become a hot research topic. As an important transcription factor in the B3 family, NGATHA1 (NGA1), plays an important role in regulating plant lateral organ development and hormone synthesis and transport, but few studies of the role of this gene in the regulation of plant growth and stress tolerance have been reported. In this study, the NGA1 gene was isolated from Medicago truncatula (Mt) and its function was characterized. The cis-acting elements upstream of the 5′ end of MtNGA1 and the expression pattern of MtNGA1 were analyzed, and the results indicated that the gene may act as a regulator of stress resistance. A plant expression vector was constructed and transgenic Arabidopsis plants were obtained. Transgenic Arabidopsis showed delayed flowering time and reduced branching phenotypes. Genes involved in the regulation of branching and flowering were differentially expressed in transgenic plants compared with wild-type plants. Furthermore, transgenic plants demonstrated strong tolerances to salt- and mannitol-induced stresses, which may be due to the upregulated expression of NCED3 (NINE-CIS-EPOXYCAROTENOID DIOXYGENASE 3) by the MtNGA1 gene. These results provide useful information for the exploration and genetic modification use of MtNGA1 in the future.

Fruit and Leaf Response to Different Source-Sink Ratios in Apple, at the Scale of the Fruit-Bearing Branch

Apple fruit growth is the result of several factors: inherent demand (relative sink strength) of the fruit (defined by the demands for cell division and expansion growth, etc.), carbon assimilation by the source leaves (source strength), and the resulting allocation to the organ in question. It is thus a complex process involving source-sink interactions. In the present study, we designed an experimental system in which parts of fruit-bearing branches of two apple cultivars ("Fuji" and "Ariane") were isolated from the rest of the tree by girdling and then subjected to specific pruning and fruit removal treatments to create a wide range of global (branch-level) source-sink ratios. We monitored not only fruit kinetics but also photosynthesis as a response to light in leaves of the three different shoot types (i.e., the rosette, the bourse, and the vegetative shoots) to 1) study the impact of source-sink distance on carbon partitioning between fruits within the same branch and 2) to investigate the impact of source/sink ratio on fruit growth and leaf photosynthetic activity. Our results indicate 1) no significant differences among lateral fruits belonging to different ranks, and this independent of source availability; 2) that a modification of the source/sink ratio seems to be compensated by an alteration of the photosynthetic rate of leaves, with stronger and weaker values obtained for lower and higher ratios, respectively. Moreover, our results seem to suggest that two growing sinks together will upregulate photosynthesis rate more strongly than one growing sink does on its own, and this with the same leaf area per fruit. These results are discussed, and some hypotheses are put forward to explain them.

Patency of Branch Vessels After Pipeline Embolization: Comparison of Various Branches

Objective: Pipeline embolization devices (PEDs) are widely used to exclude intracranial aneurysms from their parent arteries. Side branches covered by PEDs, however, sometimes experience occlusion and related symptoms. Thus, predictors of branch occlusion and the patency and clinical outcomes of these branches are concerning.

Methods: We conducted a retrospective review of consecutive patients who had been treated with PEDs in our institution during 2015–2018 to identify those in whom one or more branches were involved. Pretreatment and follow-up angiograms were assessed to determine patency of the involved branches. Demographic and clinical data, treatment strategies, and comorbidities were collected to investigate their relations with branch occlusion.

Results: Altogether, 173 branches [24 (13.9%) occluded), 29 (16.8%) with diminished flow] in 126 patients were studied. Five patients (OphA involved) presented with blurred vision and 1 patient (ACA involved) presented with headache. None of the other patients had neurologic complications or clinical strokes related to branch occlusion. Multivariate analysis identified that small PED diameter [p = 0.003, odds ratio (OR) = 0.168], branches arising from the aneurysm (p = 0.004, OR = 6.614), and involvement of the anterior cerebral artery (ACA) (p < 0.001, OR = 25.656) significantly predicted branch occlusion.

Conclusion: Branch occlusion rate after PED deployment was low and most occlusions was asymptomatic. Branches with rich collateral supply were more likely to occlude, especially the ACA. Smaller PED diameter, branches arising from the aneurysm, and ACA involvement were significant predictors of branch occlusion after PED treatment.

Ion-mediated increases in xylem hydraulic conductivity: seasonal differences between coexisting ring- and diffuse-porous temperate tree species

Ion-mediated changes in hydraulic conductivity (ΔKh) represent a mechanism allowing plants to regulate the rate of xylem transport. However, the significance of ΔKh for ring-porous (RPS) and diffuse-porous tree species (DPS) remains unknown. Here, we examined ΔKh in young branches of three coexisting, temperate RPS (Fraxinus excelsior, Quercus robur, Robinia pseudoacacia) and three DPS (Acer pseudoplatanus, Carpinus betulus, Fagus sylvatica) across the whole year, and assessed the relationships of ΔKh to branch anatomy. Ring-porous species exhibited twice as high ΔKh (10.3% vs 5.3%) within the growing season (i.e., during wood production) compared with DPS, and the production of the annual ring was identified as a crucial process affecting maximum ΔKh within the season. In addition, xylem in branches of RPS generally contained more axial parenchyma (AP; 18% vs 7%) and was characterized by a greater relative contact fraction between vessels and parenchyma (FVP; 59% vs 18%) than xylem in DPS. Simultaneously, ΔKh measured within the growing season was positively correlated with AP, FVP and bark proportions, suggesting that parenchyma in branches may be important for high ΔKh. Significant increase in ΔKh observed during the growing season may help RPS to restore conductive capacity after winter, better compensate transport loss by drought-induced embolism and thereby improve water delivery to leaves.

Is xylem of angiosperm leaves less resistant to embolism than branches? Insights from microCT, hydraulics, and anatomy

According to the hydraulic vulnerability segmentation hypothesis, leaves are more vulnerable to decline of hydraulic conductivity than branches, but whether stem xylem is more embolism resistant than leaves remains unclear. Drought-induced embolism resistance of leaf xylem was investigated based on X-ray microcomputed tomography (microCT) for Betula pendula, Laurus nobilis, and Liriodendron tulipifera, excluding outside-xylem, and compared with hydraulic vulnerability curves for branch xylem. Moreover, bordered pit characters related to embolism resistance were investigated for both organs. Theoretical P50 values (i.e. the xylem pressure corresponding to 50% loss of hydraulic conductance) of leaves were generally within the same range as hydraulic P50 values of branches. P50 values of leaves were similar to branches for L. tulipifera (-2.01 versus -2.10 MPa, respectively), more negative for B. pendula (-2.87 versus -1.80 MPa), and less negative for L. nobilis (-6.4 versus -9.2 MPa). Despite more narrow conduits in leaves than branches, mean interconduit pit membrane thickness was similar in both organs, but significantly higher in leaves of B. pendula than in branches. This case study indicates that xylem shows a largely similar embolism resistance across leaves and branches, although differences both within and across organs may occur, suggesting interspecific variation with regard to the hydraulic vulnerability segmentation hypothesis.

Cell Surface N-Glycans Influence Electrophysiological Properties and Fate Potential of Neural Stem Cells

Understanding the cellular properties controlling neural stem and progenitor cell (NSPC) fate choice will improve their therapeutic potential. The electrophysiological measure whole-cell membrane capacitance reflects fate bias in the neural lineage but the cellular properties underlying membrane capacitance are poorly understood. We tested the hypothesis that cell surface carbohydrates contribute to NSPC membrane capacitance and fate. We found NSPCs differing in fate potential express distinct patterns of glycosylation enzymes. Screening several glycosylation pathways revealed that the one forming highly branched N-glycans differs between neurogenic and astrogenic populations of cells in vitro and in vivo. Enhancing highly branched N-glycans on NSPCs significantly increases membrane capacitance and leads to the generation of more astrocytes at the expense of neurons with no effect on cell size, viability, or proliferation. These data identify the N-glycan branching pathway as a significant regulator of membrane capacitance and fate choice in the neural lineage.

Short-distance dispersal of Hypothenemus hampei (Ferrari) females (Coleoptera: Curculionidae: Scolytidae) during the coffee tree fruiting period

The coffee berry borer (CBB), Hypothenemus hampei (Ferrari), is a multivoltine species closely associated with coffee crops worldwide, causing severe damage to the bean. In Mexico, as in all tropical regions, CBB survives during the inter-harvest period in residual berries on the ground or in dry berries remaining on the branches, and then disperses in search of the first suitable berries. In this study, we investigated how CBB dispersed from the first infested nodes during the fruiting period of Coffea canephora Pierre, which provides a favourable trophic level for this insect. Forty-five branches equally distributed in 15 coffee trees, with one infested node and four uninfested nodes, were selected. The branches were subjected to three treatments over nine weeks: 1) glue between nodes with full protection, 2) glue between nodes without protection, and 3) no glue and no protection. In addition, 45 CBB-free branches were selected and subjected to the same three treatments. CBB colonization can occur in three ways: 1) from an infested node to an uninfested node on the same branch, 2) from infested berries to uninfested berries within the nodes, 3) from branches to other branches. We also found that CBB dispersal between nodes of the same branches never occurred by walking but by flying. Thus, in this context of coffee berry development and ripening, and unlike the phenological situation of the inter-harvest period, CBB continuously travels very short distances, thus limiting its control.

Ideal crop plant architecture is mediated by tassels replace upper ears1, a BTB/POZ ankyrin repeat gene directly targeted by TEOSINTE BRANCHED1

Axillary branch suppression is a favorable trait bred into many domesticated crop plants including maize compared with its highly branched wild ancestor teosinte. Branch suppression in maize was achieved through selection of a gain of function allele of the teosinte branched1 (tb1) transcription factor that acts as a repressor of axillary bud growth. Previous work indicated that other loci may function epistatically with tb1 and may be responsible for some of its phenotypic effects. Here, we show that tb1 mediates axillary branch suppression through direct activation of the tassels replace upper ears1 (tru1) gene that encodes an ankyrin repeat domain protein containing a BTB/POZ motif necessary for protein-protein interactions. The expression of TRU1 and TB1 overlap in axillary buds, and TB1 binds to two locations in the tru1 gene as shown by chromatin immunoprecipitation and gel shifts. In addition, nucleotide diversity surveys indicate that tru1, like tb1, was a target of selection. In modern maize, TRU1 is highly expressed in the leaf trace vasculature of axillary internodes, while in teosinte, this expression is highly reduced or absent. This increase in TRU1 expression levels in modern maize is supported by comparisons of relative protein levels with teosinte as well as by quantitative measurements of mRNA levels. Hence, a major innovation in creating ideal maize plant architecture originated from ectopic overexpression of tru1 in axillary branches, a critical step in mediating the effects of domestication by tb1.

Multipotent Basal Stem Cells, Maintained in Localized Proximal Niches, Support Directed Long-Ranging Epithelial Flows in Human Prostates

Sporadic mitochondrial DNA mutations serve as clonal marks providing access to the identity and lineage potential of stem cells within human tissues. By combining quantitative clonal mapping with 3D reconstruction of adult human prostates, we show that multipotent basal stem cells, confined to discrete niches in juxta-urethral ducts, generate bipotent basal progenitors in directed epithelial migration streams. Basal progenitors are then dispersed throughout the entire glandular network, dividing and differentiating to replenish the loss of apoptotic luminal cells. Rare lineage-restricted luminal stem cells, and their progeny, are confined to proximal ducts and provide only minor contribution to epithelial homeostasis. In situ cell capture from clonal maps identified delta homolog 1 (DLK1) enrichment of basal stem cells, which was validated in functional spheroid assays. This study establishes significant insights into niche organization and function of prostate stem and progenitor cells, with implications for disease.

Septins Focus Cellular Growth for Host Infection by Pathogenic Fungi

One of the key challenges faced by microbial pathogens is invasion of host tissue. Fungal pathogens adopt a number of distinct strategies to overcome host cell defenses, including the development of specialized infection structures, the secretion of proteins that manipulate host responses or cellular organization, and the ability to facilitate their own uptake by phagocytic mechanisms. Key to many of these adaptations is the considerable morphogenetic plasticity displayed by pathogenic species. Fungal pathogens can, for example, shift their growth habit between non-polarized spores, or yeast-like cells, and highly polarized hyphal filaments. These polarized filaments can then elaborate differentiated cells, specialized to breach host barriers. Septins play fundamental roles in the ability of diverse fungi to undergo shape changes and organize the F-actin cytoskeleton to facilitate invasive growth. As a consequence, septins are increasingly implicated in fungal pathogenesis, with many septin mutants displaying impairment in their ability to cause diseases of both plants and animals. In this mini-review, we show that a common feature of septin mutants is the emergence of extra polar outgrowths during morphological transitions, such as emergence of germ tubes from conidia or branches from hyphae. We propose that because septins detect and stabilize membrane curvature, they prevent extra polar outgrowths and thereby focus fungal invasive force, allowing substrate invasion.

The ratio of red light to far red light alters Arabidopsis axillary bud growth and abscisic acid signalling before stem auxin changes

Arabidopsis thaliana shoot branching is inhibited by a low red light to far red light ratio (R:FR, an indicator of competition), and by loss of phytochrome B function. Prior studies have shown that phytochrome B deficiency suppresses bud growth by elevating systemic auxin signalling, and that increasing the R:FR promotes the growth of buds suppressed by low R:FR by inhibiting bud abscisic acid (ABA) accumulation and signalling. Here, systemic auxin signalling and bud ABA signalling were examined in the context of rapid bud responses to an increased R:FR. Increasing the R:FR promoted the growth of buds inhibited by a low R:FR within 6 h. Relative to a low R:FR, bud ABA accumulation and signalling in plants given a high R:FR showed a sustained decline within 3 h, prior to increased growth. Main stem auxin levels and signalling showed a weak, transient response. Systemic effects and those localised to the bud were further examined by decapitating plants maintained either under a low R:FR or provided with a high R:FR. Increasing the R:FR promoted bud growth before decapitation, but decapitated plants eventually formed longer branches. The data suggest that rapid responses to an increased R:FR may be mediated by changes in bud ABA physiology, although systemic auxin signalling is necessary for sustained bud repression under a low R:FR.

Techniques of imaging of the aorta and its first order branches by endoscopic ultrasound (with videos)

Endoscopic ultrasonography (EUS) is a useful modality for imaging of the blood vessels of the mediastinum and abdomen. The aorta acts as an important home base during EUS imaging. The aorta and its branches are accessible by standard angiographic methods, but endosonography also provides a unique opportunity to evaluate the aorta and its branches. This article describes the techniques of imaging of different part of the aorta by EUS.

Wood specific gravity and anatomy of branches and roots in 113 Amazonian rainforest tree species across environmental gradients

Wood specific gravity (WSG) is a strong predictor of tree performance across environmental gradients. Yet it remains unclear how anatomical elements linked to different wood functions contribute to variation in WSG in branches and roots across tropical forests. We examined WSG and wood anatomy in white sand, clay terra firme and seasonally flooded forests in French Guiana, spanning broad environmental gradients found throughout Amazonia. We measured 15 traits relating to branches and small woody roots in 113 species representing the 15 most abundant species in each habitat and representative species from seven monophyletic lineages occurring in all habitats. Fiber traits appear to be major determinants of WSG, independent of vessel traits, in branches and roots. Fiber traits and branch and root WSG increased from seasonally flooded species to clay terra firme species and lastly to white sand species. Branch and root wood traits were strongly phylogenetically constrained. Lineages differed in wood design, but exhibited similar variation in wood structure across habitats. We conclude that tropical trees can invest differently in support and transport to respond to environmental conditions. Wind disturbance and drought stress represent significant filters driving tree distribution of Amazonian forests; hence we suggest that biophysical explanations should receive more attention.

Structural development of redwood branches and its effects on wood growth

Redwood branches provide all the carbohydrates for the most carbon-heavy forests on Earth, and recent whole-tree measurements have quantified trunk growth rates associated with complete branch inventories. Providing all of a tree's photosynthetic capacity, branches represent an increasing proportion of total aboveground wood production as trees enlarge. To examine branch development and its effects on wood volume growth, we dissected 31 branches from eight Sequoia sempervirens (D. Don) Endl. and seven Sequoiadendron giganteum Lindl. trees. The cambium-area-to-leaf-area ratio was maintained with size and age but increased with light availability, whereas the heartwood-deposition-area-to-leaf-area ratio increased with size and age but was insensitive to light availability. The proportion of foliage mass arrayed in <1-cm-diameter epicormic shoots increased with decreasing light and was higher in Sequoia (20-60%) than in Sequoiadendron (3-16%). Well-illuminated branches concentrated leaves higher and distally, while shaded branches distributed leaves lower and proximally. In similar light environments, older branches distributed leaves lower and more proximally than younger branches. Branch size, light, species, heartwood area, a heartwood-area-species interaction, and ovulate cone mass predicted 87.5% of the variability in wood volume growth of branches. After accounting for the positive effects of size and light, wood volume growth declined with heartwood area and age. The effect of age was trivial compared to the effect of heartwood area, suggesting that heartwood expansion caused the age-related decline in wood volume growth. Additionally, Sequoiadendron branches of similar size and light environment with more ovulate cones produced less wood, even though these cones were long-lived and photosynthetic, reflecting the energetic cost of seed production. These results contributed to a conceptual model of branch development in which light availability, injury, heartwood content, gravity, and time interact to produce the high degree of branch structural variation evident within redwood crowns.

A rapid, controlled-environment seedling root screen for wheat correlates well with rooting depths at vegetative, but not reproductive, stages at two field sites

BACKGROUND AND AIMS

Root length and depth determine capture of water and nutrients by plants, and are targets for crop improvement. Here we assess a controlled-environment wheat seedling screen to determine speed, repeatability and relatedness to performance of young and adult plants in the field.

METHODS

Recombinant inbred lines (RILs) and diverse genotypes were grown in rolled, moist germination paper in growth cabinets, and primary root number and length were measured when leaf 1 or 2 were fully expanded. For comparison, plants were grown in the field and root systems were harvested at the two-leaf stage with either a shovel or a soil core. From about the four-leaf stage, roots were extracted with a steel coring tube only, placed directly over the plant and pushed to the required depth with a hydraulic ram attached to a tractor.

KEY RESULTS

In growth cabinets, repeatability was greatest (r = 0.8, P < 0.01) when the paper was maintained moist and seed weight, pathogens and germination times were controlled. Scanned total root length (slow) was strongly correlated (r = 0.7, P < 0.01) with length of the two longest seminal axile roots measured with a ruler (fast), such that 100-200 genotypes were measured per day. Correlation to field-grown roots at two sites at two leaves was positive and significant within the RILs and cultivars (r = 0.6, P = 0.01), and at one of the two sites at the five-leaf stage within the RILs (r = 0.8, P = 0.05). Measurements made in the field with a shovel or extracted soil cores were fast (5 min per core) and had significant positive correlations to scanner measurements after root washing and cleaning (>2 h per core). Field measurements at two- and five-leaf stages did not correlate with root depth at flowering.

CONCLUSIONS

The seedling screen was fast, repeatable and reliable for selecting lines with greater total root length in the young vegetative phase in the field. Lack of significant correlation with reproductive stage root system depth at the field sites used in this study reflected factors not captured in the screen such as time, soil properties, climate variation and plant phenology.

Endovascular repair of the aortic arch in pigs by improved double-branched stent grafts

INTRODUCTION

This study aimed to evaluate the feasibility of total endovascular repair of the aortic arch in pigs using improved integrated double-branched stent grafts.

METHODS

Improved self-expandable stent grafts with a main body and two integrated branches were prepared for the repair of the aortic arch in six pigs. The feasibility of using these stent grafts was evaluated with arteriography, computed tomography (CT), computed tomography angiography (CTA) and autopsy three months following the procedure.

RESULTS

The double-branched stent grafts were placed successfully in the aortic arch in all six pigs. All pigs survived for at least three months and their biological behaviour was normal. Arteriography, CTA and animal necropsy revealed good fixation in all cases. Aortic valve function and coronary ostia remained intact, and CT of the head did not detect any lesion of cerebral infarction.

CONCLUSIONS

Endovascular repair of the aortic arch with an integrated double-branched stent graft is safe and feasible in animal studies.

Retinal vein occlusion: pathophysiology and treatment options

This paper reviews the current thinking about retinal vein occlusion. It gives an overview of its pathophysiology and discusses the evidence behind the various established and emerging treatment paradigms.

Preformation and distribution of staminate and pistillate flowers in growth units of Nothofagus alpina and N. obliqua (Nothofagaceae)

BACKGROUND AND AIMS

The distribution and differentiation times of flowers in monoecious wind-pollinated plants are fundamental for the understanding of their mating patterns and evolution. Two closely related South American Nothofagus species were compared with regard to the differentiation times and positions of staminate and pistillate flowers along their parent growth units (GUs) by quantitative means.

METHODS

Two samples of GUs that had extended in the 2004-2005 growing season were taken in 2005 and 2006 from trees in the Lanín National Park, Patagonia, Argentina. For the first sample, axillary buds of the parent GUs were dissected and the leaf, bud and flower primordia of these buds were identified. The second sample included all branches derived from the parent GUs in the 2005-2006 growing season.

KEY RESULTS

Both species developed flowering GUs with staminate and/or pistillate flowers; GUs with both flower types were the most common. The position of staminate flowers along GUs was similar between species and close to the proximal end of the GUs. Pistillate flowers were developed more distally along the GUs in N. alpina than in N. obliqua. In N. alpina, the nodes bearing staminate and pistillate flowers were separated by one to several nodes with axillary buds, something not observed in N. obliqua. Markovian models supported this between-species difference. Flowering GUs, including all of their leaves and flowers were entirely preformed in the winter buds.

CONCLUSIONS

Staminate and pistillate flowers of N. alpina and N. obliqua are differentiated at precise locations on GUs in the growing season preceding that of their antheses. The differences between N. alpina and N. obliqua (and other South American Nothofagus species) regarding flower distribution might relate to the time of anthesis of each flower type and, in turn, to the probabilities of self-pollination at the GU level.

Total and component carbon fluxes of a Scots pine ecosystem from chamber measurements and eddy covariance

BACKGROUND AND AIMS

Distinguishing between, and quantifying, the different components of ecosystem C fluxes is critical in predicting the responses of ecosystem C cycling to climate change. The aims of this study were to quantify the photosynthetic and respiratory fluxes of a 50-year-old Scots pine (Pinus sylvestris) ecosystem, and to distinguish respiration of branches with needles from that of stems, and that of soil.

METHODS

The CO2 flux of the ecosystem was continuously measured using the eddy covariance (EC) method, and its components (respiration and photosynthesis of a branch with needles, stem and soil surface) were measured with an automated chamber system, from 2001 to 2004.

KEY RESULTS

All values below are chamber based. The average temperature coefficient (Q10) of respiration was 2.7, 2.2 and 4.0, respectively, for branch (Rbran), stem (Rstem) and the soil surface (Rsoil). Respiration at a reference temperature of 15 degrees C (R15) was 1.27, 0.49 and 4.02 micromol CO2 m(-2) ground s(-1) for the three components, respectively. Over 4 years, the annual Rbran, Rstem and Rsoil ranged from 196 to 256, 56 to 83 and 439 to 598 g C m(-2) ground year(-1), respectively, with a 4-year average of 227, 72 and 507 g C m(-2) ground year(-1). Annual ecosystem respiration (Reco) was 731, 783, 909 and 751 g C m(-2) ground year(-1) in years 2001-2004, respectively, gross primary production (GPP) was 922, 1030, 1138 and 1001 g C m(-2) ground year(-1), and net ecosystem production (NEP) was 191, 247, 229 and 251 g C m(-2) ground year(-1). The average contribution of Rbran, Rstem and Rsoil to Reco was 29, 9 and 62 %, respectively. Overstorey photosynthesis accounted for 96 % of GPP. The average Reco/GPP ratio was 0.78. Net primary production (NPP) in the 4 years was 469, 581, 600 and 551 g C m(-2) year(-1), respectively, with the NPP/GPP ratio 0.54 averaged over the years.

CONCLUSIONS

Respiration from the soil is the dominant component of ecosystem respiration. Differences between years in Reco were due to differences in temperature during the growing season. Rsoil was more sensitive to temperature than Rbran and Rstem, and differences in Rsoil were responsible for the differences in Reco between years.