Distal Blade Research Articles

The WIP6 transcription factor TOO MANY LATERALS specifies vein type in C4 and C3 grass leaves

Grass leaves are invariantly strap shaped with an elongated distal blade and a proximal sheath that wraps around the stem. Underpinning this shape is a scaffold of leaf veins, most of which extend in parallel along the proximo-distal leaf axis. Differences between species are apparent both in the vein types that develop and in the distance between veins across the medio-lateral leaf axis. A prominent engineering goal is to increase vein density in leaves of C3 photosynthesizing species to facilitate the introduction of the more efficient C4 pathway. Here, we discover that the WIP6 transcription factor TOO MANY LATERALS (TML) specifies vein rank in both maize (C4) and rice (C3). Loss-of-function tml mutations cause large lateral veins to develop in positions normally occupied by smaller intermediate veins, and TML transcript localization in wild-type leaves is consistent with a role in suppressing lateral vein development in procambial cells that form intermediate veins. Attempts to manipulate TML function in rice were unsuccessful because transgene expression was silenced, suggesting that precise TML expression is essential for shoot viability. This finding may reflect the need to prevent the inappropriate activation of downstream targets or, given that transcriptome analysis revealed altered cytokinin and auxin signaling profiles in maize tml mutants, the need to prevent local or general hormonal imbalances. Importantly, rice tml mutants display an increased occupancy of veins in the leaf, providing a step toward an anatomical chassis for C4 engineering. Collectively, a conserved mechanism of vein rank specification in grass leaves has been revealed.

Direct observation of the conformational states of PIEZO1

PIEZOs are mechanosensitive ion channels that convert force into chemoelectric signals1,2 and have essential roles in diverse physiological settings3. In vitro studies have proposed that PIEZO channels transduce mechanical force through the deformation of extensive blades of transmembrane domains emanating from a central ion-conducting pore4–8. However, little is known about how these channels interact with their native environment and which molecular movements underlie activation. Here we directly observe the conformational dynamics of the blades of individual PIEZO1 molecules in a cell using nanoscopic fluorescence imaging. Compared with previous structural models of PIEZO1, we show that the blades are significantly expanded at rest by the bending stress exerted by the plasma membrane. The degree of expansion varies dramatically along the length of the blade, where decreased binding strength between subdomains can explain increased flexibility of the distal blade. Using chemical and mechanical modulators of PIEZO1, we show that blade expansion and channel activation are correlated. Our findings begin to uncover how PIEZO1 is activated in a native environment. More generally, as we reliably detect conformational shifts of single nanometres from populations of channels, we expect that this approach will serve as a framework for the structural analysis of membrane proteins through nanoscopic imaging.

A juvenile Diamantinasaurus matildae (Dinosauria: Titanosauria) from the Upper Cretaceous Winton Formation of Queensland, Australia, with implications for sauropod ontogeny

ABSTRACT Although sauropod dinosaur bones are the most abundant vertebrate fossils found in the Upper Cretaceous Winton Formation of northeast Australia, only subadult and adult specimens have been described to date. Herein, we describe the first juvenile sauropod from Australia, derived from the Winton Formation (Cenomanian–lower Turonian). The preserved material belongs to a single individual and is sufficiently diagnostic to classify as a juvenile Diamantinasaurus matildae—the third specimen to be referred to the species. It also enables the identification of a new local autapomorphy for Diamantinasaurus: a distinct tuberosity on the medial surface of the scapula, posterior to the junction of the acromion and the distal blade. Nevertheless, several morphological changes are observable between the juvenile and the two adult skeletons of Diamantinasaurus matildae. These include less well-defined or entirely absent muscle attachment sites on the juvenile bones relative to the heavily scarred and rugose adult specimens. Overlapping elements between the juvenile and the two adult skeletons indicate allometric changes for Diamantinasaurus matildae throughout ontogeny, with limb bones growing at a more rapid proportional rate than other skeletal elements. Finally, we review the global record of juvenile sauropod remains, demonstrating that the growth patterns of sauropods vary greatly between taxa. Although titanosaurs display a range of isometry and allometry in the growth of individual bones, it appears that allometric growth was the primary pattern for this group.

An Enhanced Hemostatic Ultrasonic Scalpel Based on the Longitudinal-Torsional Vibration Mode

This paper proposes an ultrasonic scalpel based on the longitudinal-torsional vibration mode to enhance the hemostatic ability. The concentrator of the proposed ultrasonic scalpel has been specially designed with spiral grooves to realize this vibration mode. The change of the working mode has enlarged the vertical motion component of the distal blade to efficiently radiate energy into the dissected tissues, supporting that the blood vessel can receive sufficient energy to be sealed. The electromechanical equivalent method has been employed in the initial design of the scalpel to obtain the desired resonance frequency. The structural optimization based on the finite element method (FEM) has been conducted to further improve the proposed design, as well as investigation of its dynamic performances. Both the conventional and presented ultrasonic scalpel prototypes were fabricated, and their important parameters such as, mechanical quality factor and resonance frequency, were tested and compared using an impedance analyzer. The ex-vivo experiments have been conducted to measure the vertical temperature distribution to investigate their transferring heat effects. The corresponding results indicated that the internal temperature values of tissues cut with the proposed hemostatic-enhanced ultrasonic scalpel are 24.0% higher on the 3mm layer, 16.5% higher on the 6mm layer, and 8.5% higher on the 9mm layer, respectively. The sealing capacity of the ultrasonic scalpels has been investigated through the coagulation dissection experiment on the chicken carotid and their burst pressure tests. The average burst pressure of the sealed vessels by the hemostatic-enhanced ultrasonic scalpel can achieve higher values than that of the conventional ultrasonic scalpel.

A new species of the alpheid shrimp genus Automate de Man, 1888 (Decapoda: Caridea) from Japan.

A new species of the alpheid shrimp genus Automate de Man, 1888, A. awaji, is described on the basis of an ovigerous female holotype and three paratype specimens (sex not determined) from Awaji Island, Hyogo Prefecture, Japan. The specimens were collected from soft sediments on a shallow subtidal flat (depth 4-8 m) using an airlift suction sampler. The new species is referred to the A. evermanni Rathbun, 1901 species group, in which seven species are currently included, from various parts of the world. Automate awaji n. sp. is characterized by the combination of the following characters: eye with cornea relatively small, in lateral and subdistal position on eyestalk; antennal scaphocerite with distolateral spine not exceeding rounded distal blade; ultimate article of maxilliped 3 with longitudinal row of setae on dorsolateral surface; cheliped ischia without spiniform setae on dorsal and ventral margins; major chela of type I smooth, not rugose or tuberculate on dorsal and ventral margins, fingers not gaping; carpus of pereopod 2 with proximal-most article less than half-length of second article; propodus of pereopod 5 with grooming apparatus consisting of closely spaced transverse rows of stiff setae. It is the fourth representative of the genus Automate reported from Japan. A brief overview on Japanese species of Automate is also given.

The Appendicular Osteology of Patagotitan Mayorum (Dinosauria, Sauropoda)

ABSTRACT Its huge size, excellent preservation, and completeness make Patagotitan mayorum a unique opportunity to explore the anatomy, paleobiological, and phylogenetic aspects linked to gigantism within Sauropoda. In this regard, we describe the appendicular skeleton of this titanosaurian species from the late Albian-aged Cerro Barcino Formation of Chubut Province, Argentina. The diagnosis of Patagotitan mayorum is revised, increasing the number of identified autapomorphies (i.e., lateral surface of the scapular blade with two divergent crests; anterior surface of proximal humerus with paired muscle scars; combined bulges on the deltopectoral area of the humerus; ischium with well-developed and sharp ridge projecting from the ischial tuberosity to the distal blade). Several diagnostic characters of this species correspond to osteological correlates associated to appendicular musculature (e.g., Mm. deltoideus scapularis, deltoideus clavicularis, and teres major; M. coracobrachialis; Mm. supracoracoideus/deltoideus clavicularis and latissimus dorsi; Mm. flexor tibialis 3 and adductor femoris 2), which we discuss in the context of sauropod evolution. In the light of a modification of the scaling equation previously proposed and adjusting the long bone circumference for the humeri of Patagotitan, a new body mass estimate of this species ranges between 42–71 tons, with a mean value of 57 tons. Although considerably less than the value obtained by the original linear equation, the corrected quadratic equation used here provides a mean body mass estimate that is more consistent with those derived from volumetric reconstructions of Patagotitan.

The Maize Hairy Sheath Frayed1 (Hsf1) Mutation Alters Leaf Patterning through Increased Cytokinin Signaling.

Leaf morphogenesis requires growth polarized along three axes-proximal-distal (P-D) axis, medial-lateral axis, and abaxial-adaxial axis. Grass leaves display a prominent P-D polarity consisting of a proximal sheath separated from the distal blade by the auricle and ligule. Although proper specification of the four segments is essential for normal morphology, our knowledge is incomplete regarding the mechanisms that influence P-D specification in monocots such as maize (Zea mays). Here, we report the identification of the gene underlying the semidominant, leaf patterning maize mutant Hairy Sheath Frayed1 (Hsf1). Hsf1 plants produce leaves with outgrowths consisting of proximal segments-sheath, auricle, and ligule-emanating from the distal blade margin. Analysis of three independent Hsf1 alleles revealed gain-of-function missense mutations in the ligand binding domain of the maize cytokinin (CK) receptor Z. mays Histidine Kinase1 (ZmHK1) gene. Biochemical analysis and structural modeling suggest the mutated residues near the CK binding pocket affect CK binding affinity. Treatment of the wild-type seedlings with exogenous CK phenocopied the Hsf1 leaf phenotypes. Results from expression and epistatic analyses indicated the Hsf1 mutant receptor appears to be hypersignaling. Our results demonstrate that hypersignaling of CK in incipient leaf primordia can reprogram developmental patterns in maize.

Detrital carbon production and export in high latitude kelp forests.

The production and fate of seaweed detritus is a major unknown in the global C-budget. Knowing the quantity of detritus produced, the form it takes (size) and its timing of delivery are key to understanding its role as a resource subsidy to secondary production and/or its potential contribution to C-sequestration. We quantified the production and release of detritus from 10 Laminaria hyperborea sites in northern Norway (69.6° N). Kelp biomass averaged 770 ± 100g C m-2 while net production reached 499 ± 50g C m-2year-1, with most taking place in spring when new blades were formed. Production of biomass was balanced by a similar formation of detritus (478 ± 41g C m-2year-1), and both were unrelated to wave exposure when compared across sites. Distal blade erosion accounted for 23% of the total detritus production and was highest during autumn and winter, while dislodgment of whole individuals and/or whole blades corresponded to 24% of the detritus production. Detachment of old blades constituted the largest source of kelp detritus, accounting for > 50% of the total detrital production. Almost 80% of the detritus from L. hyperborea was thus in the form of whole plants or blades and > 60% of that was delivered as a large pulse within 1-2months in spring. The discrete nature of the delivery suggests that the detritus cannot be retained and consumed locally and that some is exported to adjacent deep areas where it may subsidize secondary production or become buried into deep marine sediments as blue carbon.

Transcriptome sequencing of Saccharina japonica sporophytes during whole developmental periods reveals regulatory networks underlying alginate and mannitol biosynthesis

BackgroundAlginate is an important cell wall component and mannitol is a soluble storage carbon substance in the brown seaweed Saccharina japonica. Their contents vary with kelp developmental periods and harvesting time. Alginate and mannitol regulatory networks and molecular mechanisms are largely unknown.ResultsWith WGCNA and trend analysis of 20,940 known genes and 4264 new genes produced from transcriptome sequencing of 30 kelp samples from different stages and tissues, we deduced that ribosomal proteins, light harvesting complex proteins and “imm upregulated 3” gene family are closely associated with the meristematic growth and kelp maturity. Moreover, 134 and 6 genes directly involved in the alginate and mannitol metabolism were identified, respectively. Mannose-6-phosphate isomerase (MPI2), phosphomannomutase (PMM1), GDP-mannose 6-dehydrogenase (GMD3) and mannuronate C5-epimerase (MC5E70 and MC5E122) are closely related with the high content of alginate in the distal blade. Mannitol accumulation in the basal blade might be ascribed to high expression of mannitol-1-phosphate dehydrogenase (M1PDH1) and mannitol-1-phosphatase (M1Pase) (in biosynthesis direction) and low expression of mannitol-2-dehydrogenase (M2DH) and Fructokinase (FK) (in degradation direction). Oxidative phosphorylation and photosynthesis provide ATP and NADH for mannitol metabolism whereas glycosylated cycle and tricarboxylic acid (TCA) cycle produce GTP for alginate biosynthesis. RNA/protein synthesis and transportation might affect alginate complex polymerization and secretion processes. Cryptochrome (CRY-DASH), xanthophyll cycle, photosynthesis and carbon fixation influence the production of intermediate metabolite of fructose-6-phosphate, contributing to high content of mannitol in the basal blade.ConclusionsThe network of co-responsive DNA synthesis, repair and proteolysis are presumed to be involved in alginate polymerization and secretion, while upstream light-responsive reactions are important for mannitol accumulation in meristem of kelp. Our transcriptome analysis provides new insights into the transcriptional regulatory networks underlying the biosynthesis of alginate and mannitol during S. japonica developments.

Morphology and intensity of Trichodina spp. in the nilem fish larvae (Osteochilus hasselti) hatchery fish by the Kutasari Purbalingga, Central Java

Abstract. Riwidiharso E, Alfarisi B, Rokhmani. 2018. Morphology and intensity of Trichodina spp. in the nilem fish larvae (Osteochilus hasselti) hatchery fish by the Kutasari Purbalingga, Central Java. Pros Sem Nas Masy Biodiv Indon 5: 316-323. Research has been conducted to identify Trichodina sp. and intensity of Trichodina sp. on the seeds of nilem fish belonging to the Kutasari Purbalingga Fish Seed Hall. The method used in this research is survey method. Sampling is done by simple random sampling. The number of samples taken is determined using the Slovin formula in the total population known. Research variables in the form of morphology Trichodina sp. with parameters in the form of blade, apex blade, distal blade margin, tangent point, and ray shape; meristic with the parameters of the number of denticles; and morphometrics with parameters such as body diameter, denticle ring diameter, adhesive disk diameter, and border membrane width for identification of Trichodina sp .; and parasitic intensity with the number of Trichodina sp. and seeds of nilem fish infected with Trichodina sp. The results of this study, a total of 150 nilem fish seeds were observed, 105 were infected with Trichodina spp. Or 70%. Intensity of Trichodina sp. on fish seeds belonging to the Kutasari Purbalingga Fish Seed Hall of 16.08 individuals / head so that it was in the medium category. The identification of Trichodina sp. in the seeds of nilem fish with the identification of 50 individuals Trichodina sp. are species of T. acuta, T. heterodentata, T. nobilis

BLADE-ON-PETIOLE genes temporally and developmentally regulate the sheath to blade ratio of rice leaves

Axis formation is a fundamental issue in developmental biology. Axis formation and patterning in plant leaves is crucial for morphology and crop productivity. Here, we reveal the basis of proximal-distal patterning in rice leaves, which consist of a proximal sheath, a distal blade, and boundary organs formed between these two regions. Analysis of the three rice homologs of the Arabidopsis BLADE-ON-PETIOLE1 (BOP1) gene indicates that OsBOPs activate proximal sheath differentiation and suppress distal blade differentiation. Temporal expression changes of OsBOPs are responsible for the developmental changes in the sheath:blade ratio. We further identify that the change in the sheath:blade ratio during the juvenile phase is controlled by the miR156/SPL pathway, which modifies the level and pattern of expression of OsBOPs. OsBOPs are also essential for differentiation of the boundary organs. We propose that OsBOPs, the main regulators of proximal-distal patterning, control temporal changes in the sheath:blade ratio of rice leaves.

Characterization of a dominant mutation for the liguleless trait: Aegilops tauschii liguleless (Lgt)

BackgroundLeaves of Poaceae have a unique morphological feature: they consist of a proximal sheath and a distal blade separated by a ligular region. The sheath provides structural support and protects young developing leaves, whereas the main function of the blade is photosynthesis. The auricles allow the blade to tilt back for optimal photosynthesis and determine the angle of a leaf, whereas the ligule protects the stem from the entry of water, microorganisms, and pests. Liguleless variants have an upright leaf blade that wraps around the culm. Research on liguleless mutants of maize and other cereals has led to identification of genes that are involved in leaf patterning and differentiation.ResultsWe characterized an induced liguleless mutant (LM) of Aegilops tauschii Coss., a donor of genome D of bread wheat Triticum aestivum L.. The liguleless phenotype of LM is under dominant monogenic control (Lgt). To determine precise position of Lgt on the Ae. tauschii genetic map, highly saturated genetic maps were constructed containing 887 single-nucleotide polymorphism (SNP) markers derived via diversity arrays technology (DArT)seq. The Lgt gene was mapped to chromosome 5DS. Taking into account coordinates of the SNP markers, flanking Lgt, on the pseudomolecule 5D, a chromosomal region that contains this gene was determined, and a list of candidate genes was identified. Morphological features of the LM phenotype suggest that Lgt participates in the control of leaf development, mainly, in leaf proximal–distal patterning, and its dominant mutation causes abnormal ligular region but does not affect reproductive development.ConclusionsHere we report characterization of a liguleless Ae. tauschii mutant, whose phenotype is under control of a dominant mutation of Lgt. The dominant mode of inheritance of the liguleless trait in a Triticeae species is reported for the first time. The position of the Lgt locus on chromosome 5DS allowed us to identify a list of candidate genes. This list does not contain Ae. tauschii orthologs of any well-characterized cereal genes whose mutations cause liguleless phenotypes. Thus, the characterized Lgt mutant represents a new model for further investigation of plant leaf patterning and differentiation.

A lever-like transduction pathway for long-distance chemical- and mechano-gating of the mechanosensitive Piezo1 channel

Piezo1 represents a prototype of eukaryotic mechanotransduction channels. The full-length 2547-residue mouse Piezo1 possesses a unique 38-transmembrane-helix (TM) topology and is organized into a three-bladed, propeller-shaped architecture, comprising a central ion-conducting pore, three peripheral blade-like structures, and three 90-Å-long intracellular beam-resembling structures that bridge the blades to the pore. However, how mechanical force and chemicals activate the gigantic Piezo1 machinery remains elusive. Here we identify a novel set of Piezo1 chemical activators, termed Jedi, which activates Piezo1 through the extracellular side of the blade instead of the C-terminal extracellular domain of the pore, indicating long-range allosteric gating. Remarkably, Jedi-induced activation of Piezo1 requires the key mechanotransduction components, including the two extracellular loops in the distal blade and the two leucine residues in the proximal end of the beam. Thus, Piezo1 employs the peripheral blade-beam-constituted lever-like apparatus as a designated transduction pathway for long-distance mechano- and chemical-gating of the pore.

Abundant blade segments at Shuidonggou, Locality 1: Intentional or accidental?

Blades in the Initial Upper Paleolithic assemblages from Shuidonggou, Locality 1 (SDG1) are frequently fragmented. Complete blades are rare and proximal, medial and distal blade segments are abundant in the collections from various excavation campaigns at the site. Using a large sample of artifacts from 1963 excavations at the SDG 1 site, this paper evaluates the hypothesis that blades were intentionally broken into regular sections, perhaps to facilitate their insertion into armatures of composite tools. The scarcity of traces of percussion and hafting-related modification, and the non-standardized lengths of segments do not suggest intentional human intervention in sectioning the blades. Instead, the strong correlation between segment length and a measure of blade strength suggests that most if not all blade sections resulted from accidental breakage.

Regrowth and biofouling in two species of cultivated kelp in the Shetland Islands, UK

The meristem of the kelps Laminaria digitata and Saccharina latissima is located at the base of the blade, growth can therefore continue when the distal blade is lost due to erosion or harvesting. The aim of the study was to determine the regrowth potential of cultivated kelp in the Shetland Islands (UK) to assess feasibility of harvesting twice in one growing season. Laminaria digitata and S. latissima grown on longlines at sea were sampled between March and August, and harvested either at the stipe (whole) or 10 cm above the stipe-blade transition zone (partial) May–August. Image analysis was used to estimate blade length, width, area and fouled area. S. latissima increased in length more than L. digitata between March and August, and in August, while whole S. latissima experienced a net loss in length, partially cut blades had a net increase. Whole blades significantly increased in length for both species but only partially cut S. latissima significantly regrew. In late summer, severe biofouling by tunicates made up 12 and 27% of the biomass at two sites. Interestingly, S. latissima was less fouled than L. digitata. Consequently, S. latissima shows the greatest potential for the application of partial cutting to improve cultivated biomass yields. However, the period for regrowth is limited by low yields in early spring and blade degradation in late summer. In order to optimise biomass yields, further understanding is needed on the abiotic and biotic factors that control growth and biofouling on natural and farmed seaweed.

Additional data on Iranian trichodorids (Triplonchida: Trichodoridae) and first record of a rare species, Trichodorus variabilis Roca, 1998

Trichodorus variabilis, recovered from three separate locations in natural forests of northern Iran, was studied using morphological, morphometric and molecular data. Variation in position of the ventromedian cervical papillae (CP1 and CP2) with respect to the onchiostyle base in the resting position, and spicule characters (having or lacking striation in distal blade region and bristles in proximal blade region) were observed. Variation was also observed in the nature of the pharyngo-intestinal junction (offset to slight overlapping). The secretory-excretory pore of females also showed slight variation in placement. Molecular phylogenetic studies, using partial 28S rDNA D2-D3 sequences of three studied populations and one sequenced isolate of the species from Greece, revealed T. variabilis has variation in the sequences of this genomic fragment. The similarity percent of four sequences ranged from 96.7 to 99.7%. The species was found for the first time outside of Greece, the country from which it was originally described. A newly recovered population of T. persicus, originally described from Iran, was also included in the molecular phylogenetic analyses.

The barley Uniculme4 gene encodes a BLADE-ON-PETIOLE-like protein that controls tillering and leaf patterning.

Tillers are vegetative branches that develop from axillary buds located in the leaf axils at the base of many grasses. Genetic manipulation of tillering is a major objective in breeding for improved cereal yields and competition with weeds. Despite this, very little is known about the molecular genetic bases of tiller development in important Triticeae crops such as barley (Hordeum vulgare) and wheat (Triticum aestivum). Recessive mutations at the barley Uniculme4 (Cul4) locus cause reduced tillering, deregulation of the number of axillary buds in an axil, and alterations in leaf proximal-distal patterning. We isolated the Cul4 gene by positional cloning and showed that it encodes a BROAD-COMPLEX, TRAMTRACK, BRIC-À-BRAC-ankyrin protein closely related to Arabidopsis (Arabidopsis thaliana) BLADE-ON-PETIOLE1 (BOP1) and BOP2. Morphological, histological, and in situ RNA expression analyses indicate that Cul4 acts at axil and leaf boundary regions to control axillary bud differentiation as well as the development of the ligule, which separates the distal blade and proximal sheath of the leaf. As, to our knowledge, the first functionally characterized BOP gene in monocots, Cul4 suggests the partial conservation of BOP gene function between dicots and monocots, while phylogenetic analyses highlight distinct evolutionary patterns in the two lineages.

Transcriptomic analyses indicate that maize ligule development recapitulates gene expression patterns that occur during lateral organ initiation.

Development of multicellular organisms proceeds via the correct interpretation of positional information to establish boundaries that separate developmental fields with distinct identities. The maize (Zea mays) leaf is an ideal system to study plant morphogenesis as it is subdivided into a proximal sheath and a distal blade, each with distinct developmental patterning. Specialized ligule and auricle structures form at the blade-sheath boundary. The auricles act as a hinge, allowing the leaf blade to project at an angle from the stem, while the ligule comprises an epidermally derived fringe. Recessive liguleless1 mutants lack ligules and auricles and have upright leaves. We used laser microdissection and RNA sequencing to identify genes that are differentially expressed in discrete cell/tissue-specific domains along the proximal-distal axis of wild-type leaf primordia undergoing ligule initiation and compared transcript accumulation in wild-type and liguleless1-R mutant leaf primordia. We identified transcripts that are specifically upregulated at the blade-sheath boundary. A surprising number of these "ligule genes" have also been shown to function during leaf initiation or lateral branching and intersect multiple hormonal signaling pathways. We propose that genetic modules utilized in leaf and/or branch initiation are redeployed to regulate ligule outgrowth from leaf primordia.

Comparative Osteology and Phylogenetic Relationship ofEdmontosaurusandShantungosaurus(Dinosauria: Hadrosauridae) from the Upper Cretaceous of North America and East Asia

The close affinity between Edmontosaurus and Shantungosaurus is corroborated on the basis of the following shared features: an occipital condyle deflected strongly posteroventrally; a posterodorsally reflected, lip-shaped oral margin of the premaxilla, with a deep, oval concavity at the anteromedial corner of the bone; a well-demarcated posterodorsal margin of the deeply excavated circumnarial fossa formed by a prominent arched ridge along the entire posterior half of the lateroventral border of the nasal; an anteroposteriorly broad jugal process of the postorbital; a strongly concave dorsal surface of the paired frontals; seven teeth per alveolus in the middle of the dentary tooth row; and a circular distal blade of the pubis that is much more expanded ventrally than dorsally. A revised phylogenetic analysis of Hadrosauroidea recovers a sister taxon relationship between Edmontosaurus and Shantungosaurus. Kerberosaurus is recovered as the sister taxon to the clade formed exclusively by these two genera. The clade Edmontosaurini could be defined as the least inclusive clade containing Kerberosaurus and Edmontosaurus, which is currently composed of the genera Kerberosaurus, Edmontosaurus, and Shantungosaurus. Zhuchengosaurus and Huaxiaosaurus, both from the Upper Cretaceous Wangshi Group in Zhucheng, are interpreted as junior synonyms of Shantungosaurus. Kundurosaurus is likewise considered a junior synonym of Kerberosaurus. The strict consensus tree together with biogeographic information indicates that the clade Edmontosaurini originated in Asia and subsequently dispersed into North America.

Risk of injury to the axillary nerve during antegrade proximal humeral blade nail fixation – An anatomical study

IntroductionThe antegrade intramedullary Locking Blade Nail (Marquardt, Germany) is a device aimed at improving purchase in the humeral head and reducing varus displacement by providing medial buttress support and triangular stability within the humeral head. The aim of this study is to measure the relationship of the proximal fixation screws to the axillary nerve. Methods13 whole cadavers underwent insertion of an antegrade proximal humeral blade nail via a deltoid split approach to both shoulders. The anatomic proximity of the anterior branch of the axillary nerve to the screws was measured following soft tissue dissection and inspection of the nerve. ResultsThe mean distance of the nerve from the anterolateral acromion was 62mm (range 45–81mm). The nerve lay closest to the distal blade fixation screw 4.9mm (range 0–19mm). In three cases the nerve lay directly underneath the washer and in all three cases there was macroscopic evidence of damage to the nerve. In 5 cases the nerve travelled obliquely in a cranial direction to lie 1.8mm (range 0–3mm) from the distal blade fixation screw, in 2 of these cases the nerve lay beneath the washer. ConclusionThe anterior branch of the axillary nerve is placed at risk during insertion of the locking screws despite use of protection sleeves and trocars. We advocate that when using antegrade intramedullary nails that incorporate an inferomedial calcar screw an extended anterolateral acromial approach is undertaken.