Tree ring anatomy indices of Pinus tabuliformis revealed the shifted dominant climate factor influencing potential hydraulic function in western Qinling Mountains

Trees can adjust xylem anatomical structure related with potential hydraulic functions to cope with climate variability. We therefore need a better understanding of how climate variability constrains wood anatomy and tree radial growth. Pinus tabuliformis dominates natural forests and plantations over the western Qinling Mountains, which is one of the ecologically vulnerable areas in China. Here, we investigated the response of P. tabuliformis tree-ring anatomical structure to climate variability by applying wood anatomy analysis, and evaluated the influences of anatomical traits on potential hydraulic functions and the climate significance of intra-annual density fluctuations (IADFs). We found that with the increasing temperature from spring to summer, the negative effect of temperature on the formation and enlargement of earlywood and transition-wood tracheids was gradually enhanced. However, spring precipitation not only had a direct and positive influence on the formation of earlywood, but also had a delaying impact on the transition-wood cell enlargement. Besides, the smaller earlywood tracheid size of P. tabuliformis could be a substantially characteristic reflecting spring drought. The contribution of lumen diameter on conduit wall reinforcement was dominated in earlywood, while the contribution of cell wall thickness was greater than that of lumen diameter in latewood. The different contributions of anatomical traits on conduit wall reinforcement would further affect the response of potential hydraulic function to climate. IADFs of P. tabuliformis could be a potential indicator to reflect the abnormal summer precipitation events in the western Qinling Mountains. IADFs with strong and weak intensity indicated years with high and low rates of change in mid-summer precipitation, respectively. Future warmer and drier climate in the western Qinling Mountains will likely result in the production of smaller tracheids to ensure hydraulic safety, which means the stronger drought resistant of P. tabuliformis in the future. In this study, we linked the xylem anatomy and potential hydraulics functions with intra-seasonal climate variability in the context of climate warming and drying, and proposed some xylem anatomical indices reflecting potential drought events.     

Filamin structure,function and mechanics: are altered filamin-mediated force responses associated with human disease?

The cytoskeleton framework is essential not only for cell structure and stability but also for dynamic processes such as cell migration, division and differentiation. The F-actin cytoskeleton is mechanically stabilised and regulated by various actin-binding proteins, one family of which are the filamins that cross-link F-actin into networks that greatly alter the elastic properties of the cytoskeleton. Filamins also interact with cell membrane-associated extracellular matrix receptors and intracellular signalling proteins providing a potential mechanism for cells to sense their external environment by linking these signalling systems. The stiffness of the external matrix to which cells are attached is an important environmental variable for cellular behaviour. In order for a cell to probe matrix stiffness, a mechanosensing mechanism functioning via alteration of protein structure and/or binding events in response to external tension is required. Current structural, mechanical, biochemical and human disease-associated evidence suggests filamins are good candidates for a role in mechanosensing.     

Gross intestinal morphometry and allometry in primates

Although it is generally assumed that among mammals and within mammal groups, those species that rely on diets consisting of greater amounts of plant fiber have larger gastrointestinal tracts (GIT), statistical evidence for this simple claim is largely lacking. We compiled a dataset on the length of the small intestine, caecum, and colon in 42 strepsirrhine, platyrrhine, and catarrhine primate species, using specimens with known body mass (BM). We tested the scaling of intestine length with BM, and whether dietary proxies (percentage of leaves and a diet quality index) were significant covariates in these scaling relationships, using two sets of models: one that did not account for the phylogenetic structure of the data, and one that did. Intestine length mainly scaled geometrically at exponents that included 0.33 in the confidence interval; Strepsirrhini exhibited particularly long caeca, while those of Catarrhini were comparatively short. Diet proxies were only significant for the colon and the total large intestine (but not for the small intestine or the caecum), and only in conventional statistics (but not when accounting for phylogeny), indicating the pattern occurred across but not within clades. Compared to terrestrial Carnivora, primates have similar small intestine lengths, but longer large intestines. The data on intestine lengths presented here corroborate recent results on GIT complexity, suggesting that diet, as currently described, does not exhaustively explain GIT anatomy within primate clades.     

Deconstructing the long-standing a priori assumption that serial homology generally involves ancestral similarity followed by anatomical divergence

It has long been assumed that serial homologues are ancestrally similar—polysomerism resulting from a “duplication” or “repetition” of forms—and then often diverge—anisomerism, for example, as they become adapted to perform different tasks as is the case with the forelimb and hind limbs of humans. However, such an assumption, with crucial implications for comparative, evolutionary, and developmental biology, and for evolutionary developmental biology, has in general not really been tested by a broad analysis of the available empirical data. Perhaps not surprisingly, more recent anatomical comparisons, as well as molecular knowledge of how, for example, serial appendicular structures are patterned along with different anteroposterior regions of the body axis of bilateral animals, and how “homologous” patterning domains do not necessarily mark “homologous” morphological domains, are putting in question this paradigm. In fact, apart from showing that many so-called “serial homologues” might not be similar at all, recent works have shown that in at least some cases some “serial” structures are indeed more similar to each other in derived taxa than in phylogenetically more ancestral ones, as pointed out by authors such as Owen. In this article, we are taking a step back to question whether such assumptions are actually correct at all, in the first place. In particular, we review other cases of so-called “serial homologues” such as insect wings, arthropod walking appendages, Dipteran thoracic bristles, and the vertebrae, ribs, teeth, myomeres, feathers, and hairs of chordate animals. We show that: (a) there are almost never cases of true ancestral similarity; (b) in evolution, such structures—for example, vertebra—and/or their subparts—for example, “transverse processes”—many times display trends toward less similarity while in many others display trends toward more similarity, that is, one cannot say that there is a clear, overall trend to anisomerism.     

Aging leads to inferior Achilles tendon mechanics and altered ankle function in rodents

Spontaneous rupture of the Achilles tendon is increasingly common in the middle aged population. However, the cause for the particularly high incidence of injury in this age group is not well understood. Therefore, the objective of this study was to identify age-specific differences in the Achilles tendon-muscle complex using an animal model. Functional measures were performed in vivo and tissues were harvested following euthanasia for mechanical, structural, and histological analysis from young, middle aged, and old rats. Numerous alterations in tendon properties were detected across age groups, including inferior material properties (maximum stress, modulus) with increasing age. Differences in function were also observed, as older animals exhibited increased ankle joint passive stiffness and decreased propulsion force during locomotion. Macroscale differences in tendon organization were not observed, although cell density and nuclear shape did vary between age groups. Muscle fiber size and type distribution were not notably affected by age, indicating that other factors may be more responsible for age-specific Achilles tendon rupture rates. This study improves our understanding of the role of aging in Achilles tendon biomechanics and ankle function, and helps provide a potential explanation for the disparate incidence of Achilles tendon ruptures in varying age groups.     

A comparative study of the leaves of Cat hay a argyrophylla Chun & Kuang and three species of Keteleeria Carrière

Details of the cuticular, epidermal and anatomical features of the leaves of Cathaya argyrophylla Chun & Kuang, are described and compared with those of three species of Keteleeria (K. davidiana (Bertrand) Beissner, K. fortunei (Murray) Carriere, and K. chien-peii Flous). The study supports the creation of Cathaya Chun & Kuang as a new genus of the Pinaceae.     

Chemical and physical methods in dating human skeletal remains

Chemical and physical methods for dating skeletal remains were examined. Benzidine reaction, ultra-violet fluorescence, specific gravity and supersonic conductivity were carried out on 71 dated skeletal findings distributed over the span of the last 3,500 years. Results given by benzidine reaction and ultra-violet fluorescence basically coincide, and positive readings were obtained up to about 200–350 years. Values measured in specific gravity and supersonic conductivity testing show a parallel trend, pointing out a clear difference between samples of the three first centuries and the ones belonging to more ancient periods examined.     

Large Tristichopteridae (Sarcopterygii, Tetrapodomorpha) from the Late Famennian Evieux Formation of Belgium

Remains of two large sarcopterygians are described from Famennian deposits in Belgium. One of them is referred to Eusthenodon wängsjöi Jarvik; it is the first occurrence of this genus in Belgium. The other, much larger one, appears to be a tristichopterid. It has a postspiracular; size and shape of the mandible similar to those of Platycephalichthys skuenicus and P. bischoffi ; snout and cheek patterns close to those of Eusthenodon ; unusual shape of the supratemporal resembling that of Hyneria , Mandageria and Platycephalichthys skuenicus ; and tooth histology quite similar to that of Eusthenodon and Platycephalichthys .     

The performance of morphological characters in broad-scale phylogenetic analyses

In view of their propositional content (i.e. they can be right or wrong), character statements (i.e. statements that predicate characters of organisms) are treated as low-level hypotheses. The thesis of the present study is that such character statements, as do more complex scientific theories, come with variable scope. The scope of a hypothesis, or theory, is the domain of discourse over which the hypothesis, or theory, ranges. A character statement is initially introduced within the context of a certain domain of discourse that is defined by the scale of the initial phylogenetic analysis. The doctrine of 'total evidence' requires the inclusion of previously introduced characters in subsequent studies. As a consequence, the initial scope of character statements is widened to the extent that the scale of subsequent analyses is broadened. Scope expansion for character statements may result in incomplete characters, in the subdivision of characters, or in ambiguity of reference (indeterminacy of the extension of anatomical terms). Character statements with a wide scope are desirable because they refer to characters with the potential to resolve deep nodes in phylogenetic analyses. Care must be taken to preserve referential unambiguity of anatomical terms if the originally restricted scope of a character statement is expanded to match a broad-scale phylogenetic analysis.  © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 92 , 297–308.