Does the photosynthetic light‐acclimation need change in leaf anatomy?

There is a strong correlation between leaf thickness and the light‐saturated rate of photosynthesis per unit leaf area (P_max). However, when leaves are exposed to higher light intensities after maturation, P_max often increases without increasing leaf thickness. To elucidate the mechanism with which mature leaves increase P_max, the change in anatomical and physiological characteristics of mature leaves of Chenopodium album, which was transferred from low to high light condition, were examined. When compared with leaves subjected to low light continuously (LL leaves), the leaves transferred from low to high light (LH leaves) significantly increased P_max. The transfer also increased the area of chloroplasts facing the intercellular space (S_c) and maintained a strong correlation between P_max and S_c. The mesophyll cells of LL leaves had open spaces along cell walls where chloroplasts were absent, which enabled the leaves to increase P_max when they were exposed to high light (LH). However, the LH leaves were not thick enough to allow further increase in P_max to the level in HH leaves. Thus leaf thickness determines an upper limit of P_max of leaves subjected to a change from low to high light conditions. Shade leaves would only increase P_max when they have open space to accommodate chloroplasts which elongate after light conditions improve.     

Dendroclimatic potential of dendroanatomy in temperature-sensitive Pinus sylvestris

The most frequently and successfully used tree-ring parameters for the study of temperature variations are ring width and maximum latewood density (MXD). MXD is preferred over ring width due to a more prominent association with temperature. In this study we explore the dendroclimate potential of dendroanatomy based on the first truly well replicated dataset. Twenty-nine mature living Pinus sylvestris trees were sampled in North-eastern Finland at the cool and moist boreal forest zone, close to the latitudinal tree line, where ring width, X-ray MXD as well as the blue intensity counterpart MXBI were compared with dendroanatomical parameters. Maximum radial cell wall thickness as well as anatomical MXD and latewood density appeared to be the most promising parameters for temperature reconstruction. In fact, these parameters compare favorably to MXD derived from X-ray techniques as well as MXBI, in terms of shared variation and temperature correlations across frequencies and over time. The reasons for these results are thought to be the unprecedentedly high measurement resolution of the anatomical technique, which provide the optimal resolution – the cell – whereas X-ray techniques have a slightly lower resolution and BI techniques even lower. While the results of this study are encouraging, further tests on longer and multigenerational chronologies are required to more generally and fully assess the dendroclimate potential of anatomical parameters.     

A reconsideration of the reptilian relationships of Archaeopteryx

The cladistic relationships of Archaeopteryx , the earliest known bird, are re-examined and previous hypotheses of relationships evaluated. The morphology of Archaeopteryx is redescribed. New interpretations of the fossils are presented, particularly in regard to the morphology of the pectoral girdle, manus, pelvic girdle, tarsus and pes. These new interpretations challenge some of the phylogenetic hypotheses recently presented and a new version of thecodontian relationships is suggested.     

鹅掌柴花蜜腺的发育解剖学研究

对鹅掌柴(Scheffler octophylla Harms．)花蜜腺的发育进行解剖结构观察。鹅掌柴花盘蜜腺位于下位子房上方环绕花柱基部。蜜腺由分泌表皮、产蜜组织组成,心皮维管束与其相邻并发出一些伸入蜜腺基部的短分枝。蜜腺起源于心皮原基基部外侧的几层细胞。鹅掌柴花蜜腺为淀粉型蜜腺,淀粉粒为许多微小颗粒聚集成的复粒。原蜜汁由蜜腺基部维管束的筛管提供,达产蜜组织细胞和表皮细胞后以淀粉粒的形式贮藏。泌出的蜜汁一部分来自淀粉粒的降解,一部分来自泌蜜期输入的原蜜汁。表皮和产蜜组织细胞均具泌蜜功能。泌出的蜜汁大部分通过气孔排出,还有部分由角质层渗出。     

Leaf photosynthetic traits scale with hydraulic conductivity and wood density in Panamanian forest canopy trees

We investigated how water transport capacity, wood density and wood anatomy were related to leaf photosynthetic traits in two lowland forests in Panama. Leaf-specific hydraulic conductivity (k_L) of upper branches was positively correlated with maximum rates of net CO₂ assimilation per unit leaf area (A_area) and stomatal conductance (g_s) across 20 species of canopy trees. Maximum k_L showed stronger correlation with A_area than initial k_L suggesting that allocation to photosynthetic potential is proportional to maximum water transport capacity. Terminal branch k_L was negatively correlated with A_area/g_s and positively correlated with photosynthesis per unit N, indicating a trade-off of efficient use of water against efficient use of N in photosynthesis as water transport efficiency varied. Specific hydraulic conductivity calculated from xylem anatomical characteristics (k_theoretical) was positively related to A_area and k_L, consistent with relationships among physiological measurements. Branch wood density was negatively correlated with wood water storage at saturation, k_L, A_area, net CO₂ assimilation per unit leaf mass (A_mass), and minimum leaf water potential measured on covered leaves, suggesting that wood density constrains physiological function to specific operating ranges. Kinetic and static indices of branch water transport capacity thus exhibit considerable co-ordination with allocation to potential carbon gain. Our results indicate that understanding tree hydraulic architecture provides added insights to comparisons of leaf level measurements among species, and links photosynthetic allocation patterns with branch hydraulic processes.     

自然贮存苹果的生化分析及形态解剖学研究

本文对自然贮存六个月的秦冠、红富士及新红星苹果果实在生化成分及显微、超微结构上进行了对比研究,发现红富士果实中果胶质、总糖及粗蛋白含量均高于其它品种;三种果实表面均有不同形态的蜡质分布;果皮角化层以红富士较厚,新红星次之;不同品种果肉细胞的形态有明显差异。本文对此结果进行了初步的探讨,以期为苹果贮存研究积累资料。     

葡萄属营养器官的比较解剖学及其系统学意义

本文对国产葡萄属24个种、6个变种和4个美洲种进行了比较解剖学研究。比较观察了茎、节、 叶柄、叶片的维管系统、厚角组织、厚壁组织、毛状体、后含物、叶表皮角质等解剖学特征。并讨论了它们在系统学上的意义。     

铁筷子(毛茛科)营养器官的结构及其系统学意义

应用解剖学方法,对铁筷子(Helleborus thibetanusFranch.)(毛茛科)营养器官的结构进行了研究。结果表明,铁筷子根的初生结构观察到三原型、四原型和六原型。营养器官中的维管束在横切面上木质部中的导管分子不呈“V”字形排列;根状茎的次生结构由外向内为表皮、皮层和维管柱,髓射线发达。茎的初生结构中多个维管束排列成环状,维管束鞘分化不明显,节部为单隙三迹,叶迹分别来自于3条维管束或同一条维管束。叶为两面叶,表皮细胞不规则;气孔器只分布于下表皮,为毛茛科典型的无规则型气孔。从铁筷子营养器官的解剖学特点来看,与毛茛科其它植物基本相同,但在营养器官中维管束木质部不呈“V”字形、维管束鞘分化不明显、节部具单叶隙等特征上与其它毛茛科植物不同。     

Musculoskeletal morphology of the pelvis and pelvic fins in the lungfish Protopterus annectens

The West African lungfish (Protopterus annectens) performs benthic, pelvic fin‐driven locomotion with gaits common to tetrapods, the sister group of the lungfishes. Features of P. annectens movement are similar to those of modern tetrapods and include use of the distal region of the pelvic fin as a “foot,” use of the fin to lift the body above the substrate and rotation of the fin around the joint with the pelvis. In contrast to these similarities in movement, the pelvic fins of P. annectens are long, slender structures that are superficially very different from tetrapod limbs. Here, we describe the musculoskeletal anatomy of the pelvis and pelvic fins of P. annectens with dissection, magnetic resonance imaging, histology and 3D‐reconstruction methods. We found that the pelvis is embedded in the hypaxial muscle by a median rostral and two dorsolateral skeletal projections. The protractor and retractor muscles at the base of the pelvic fin are fan‐shaped muscles that cup the femur. The skeletal elements of the fin are serially repeating cartilage cylinders. Along the length of the fin, repeating truncated cones of muscles, the musculus circumradialis pelvici, are separated by connective tissue sheets that connect the skeletal elements to the skin. The simplicity of the protractor and retractor muscles at the base of the fin is surprising, given the complex rotational movement those muscles generate. In contrast, the series of many repeating segmental muscles along the length of the fin is consistent with the dexterity of bending of the distal limb. P. annectens can provide a window into soft‐tissue anatomy and sarcopterygian fish fin function that complements the fossil data from related taxa. This work, combined with previous behavioral examination of P. annectens, illustrates that fin morphologies that do not appear to be capable of walking can accomplish that function, and may inform the interpretation of fossil anatomical evidence. J. Morphol. 275:431–441, 2014. © 2013 Wiley Periodicals, Inc.     

Anatomical study of zygotic and somatic embryos of Tilia cordata

A comparative anatomical study was carried out on zygotic and somatic embryos of Tilia cordata Mill. to evaluate the effect of growth conditions on their development. Zygotic embryos (heart-shaped, torpedo, cotyledonary), collected during two autumn periods, were examined to investigate the effect of growing season on embryo development. In comparison, the influence of growth conditions on the development of somatic embryos in vitro was also studied. Treatment with abscisic acid (ABA) and polyethylene glycol-4000 induced the development of somatic cotyledonary embryos similar to zygotic embryos with respect to morphology and anatomy, as illustrated by the differentiation of the apical meristems and of the procambium. The pattern of accumulation of starch and protein was also similar in these embryos. Somatic cotyledonary embryos that developed spontaneously without ABA showed defective accumulation of storage material and a general failure to form the shoot apical meristem, leading to very low germination rates. Vacuolar phenolic deposits were observed along the procambium of both zygotic and somatic embryos regardless of the maturation stage. Tracheid formation was observed only in somatic embryos formed without ABA in the medium and in precociously germinated somatic embryos. Phenolic vacuolar inclusions were frequently observed in epidermal cells of these embryos. This revised version was published online in June 2006 with corrections to the Cover Date.