Occurrence and distribution of sesamoid bones in squamates: a comparative approach

Jerez, A., Mangione, S. and Abdala, V. 2010. Occurrence and distribution of sesamoid bones in squamates: a comparative approach.—Acta Zoologica (Stockholm) 91 : 295–305 Sesamoids are defined as skeletal elements that develop within a continuous band of regular dense connective tissue (tendon or ligament) adjacent to an articulation or joint. In this work, we discuss developmental data on two squamate species, provide data on the onset of the squamate sesamoids and the muscles they are associated to. Our results show that Mabuya mabouya and Liolaemus albiceps exhibited rather similar ontogenetic patterns and that the first sesamoids appear in embryos. The ossifying sesamoid timing is different between M. mabouya and L. albiceps, being faster in the former. In adults, we found 41 sesamoids, considering both fore and hindlimbs. We did not find any intrataxonomic differences, or any differences between the right and left side of the specimens in relation to the sesamoid presence. We recognize four types of sesamoids: (1) embedded sesamoids; (2) interosseus sesamoids; (3) glide sesamoids; and (4) supporting sesamoids. A table is included with a preliminary survey of the sesamoid distribution pattern in 10 Squamate clades.     

Sesamoids in tetrapods: the origin of new skeletal morphologies

Along with supernumerary bones, sesamoids, defined as any organized intratendinous/intraligamentous structure, including those composed of fibrocartilage, adjacent to an articulation or joint, have been frequently considered as enigmatic structures associated with the joints of the skeletal system of vertebrates. This review allows us to propose a dynamic model to account for part of skeletal phenotypic diversity: during evolution, sesamoids can become displaced, attaching to and detaching from the long bone epiphyses and diaphysis. Epiphyses, apophyses and detached sesamoids are able to transform into each other, contributing to the phenotypic variability of the tetrapod skeleton. This dynamic model is a new paradigm to delineate the contribution of sesamoids to skeletal diversity. Herein, we first present a historical approach to the study of sesamoids, discussing the genetic versus epigenetic theories of their genesis and growth. Second, we construct a dynamic model. Third, we present a summary of literature on sesamoids of the main groups of tetrapods, including veterinary and human clinical contributions, which are the best‐studied aspects of sesamoids in recent decades. Finally, we discuss the identity of certain structures that have been labelled as sesamoids despite insufficient formal testing of homology. We also propose a new definition to help the identification of sesamoids in general. This review is particularly timely, given the recent increasing interest and research activity into the developmental biology and mechanics of sesamoids. With this updated and integrative discussion, we hope to pave the way to improve the understanding of sesamoid biology and evolution.     

Sesamoid bones in tuatara (Sphenodon punctatus) investigated with X‐ray microtomography,and implications for sesamoid evolution in Lepidosauria

Sesamoids bones are small intra‐tendinous (or ligamentous) ossifications found near joints and are often variable between individuals. Related bones, lunulae, are found within the menisci of certain joints. Several studies have described sesamoids and lunulae in lizards and their close relatives (Squamata) as potentially useful characters in phylogenetic analysis, but their status in the extant outgroup to Squamata, tuatara (Sphenodon ), remains unclear. Sphenodon is the only living rhynchocephalian, but museum specimens are valuable and difficult to replace. Here, we use non‐destructive X‐ray microtomography to investigate the distribution of sesamoids and lunulae in 19 Sphenodon specimens and trace the evolution of these bones in Lepidosauria (Rhynchocephalia + Squamata). We find adult Sphenodon to possess a sesamoid and lunula complement different from any known squamate, but also some variation within Sphenodon specimens. The penultimate phalangeal sesamoids and tibial lunula appear to mineralize prior to skeletal maturity, followed by mineralization of a sesamoid between metatarsal I and the astragalocalcaneum (MTI‐AC), the palmar sesamoids, and tibiofemoral lunulae around attainment of skeletal maturity. The tibial patella, ulnar, and plantar sesamoids mineralize late in maturity or variably. Ancestral state reconstruction indicates that the ulnar patella and tibiofemoral lunulae are synapomophies of Squamata, and the palmar sesamoid, tibial patella, tibial lunula, and MTI‐AC may be synapomorphies of Lepidosauria. J. Morphol. 278:62–72, 2017. ©© 2016 Wiley Periodicals,Inc.     

Sesamoids and Morphological Variation: a Hypothesis on the Origin of Rod-like Skeletal Elements in Aerial Mammals

Enigmatic rod-like skeletal structures that support compliant membranes (patagia) in aerial mammals have been often considered as neomorphic elements or as evolutionary novelties, and their origin has remained poorly understood. A potential source of skeletal plasticity and, probably, of morphofunctional innovations are sesamoids, which were recently demonstrated to have a common cellular origin with bone eminences. In this review, I compile information regarding anatomy, evolution, and development of rod-like skeletal elements in extant gliding and flying mammals and propose a working hypothesis on the origin of these structures. Rod-like skeletal elements, namely, the calcar in bats (Chiroptera), the unciform element in Anomaluridae (Rodentia), and the styliform cartilage in Pteromyini (Rodentia: Sciuridae), would derive from sesamoids, which, in turn, would have the same origin as eminences of long bones (or bones with a long-bone-like growth), i.e., calcaneus, ulna, and pisiform, respectively. Rod-like skeletal elements exhibit several features of sesamoids. However, further developmental data are needed to confirm this hypothesis, particularly whether these structures share a cellular origin and molecular developmental pathways with sesamoids and bone eminences. If this hypothesis were supported, a new role for sesamoids in generating morphofunctional innovations in mammals and, potentially, in other aerial amniotes, would be recognized. Rod-like skeletal elements, which are key in the evolution of aerial locomotion, might constitute an example of pre-existing traits that acquire novel functions through relatively little developmental plasticity.

     

How common are cranial sesamoids among squamates?

Sesamoids are elements that originate as intratendinous structures due to genetic and epigenetic factors. These elements have been reported frequently in vertebrates, although cranial sesamoids have been recorded almost exclusively in non‐tetrapod Osteichthyes. The only tetrapod cranial sesamoids reported until now have been the transiliens cartilage (of crocodiles and turtles), and another one located in the quadrate‐mandibular joint of birds. Here, we examined seven squamate species using histological sections, dissections of preserved specimens, dry skeletons, cleared and stained specimens, computed tomographies (CT), and report the presence of other cranial sesamoids. One is attached to the cephalic condyle of the quadrate, embedded in the bodenaponeurosis and jaw adductor muscles of Ophiodes intermedius (Anguidae). The other sesamoid is found at the base of the basicranium of several squamates, capping the sphenoccipital tubercle, on the lateral side of the basioccipital–basisphenoid suture. This bone has previously been reported as “element X.” We reinterpret it as a basicranial sesamoid, as it is associated with tendons of the cranio‐cervical muscles. This bone seems to have the function of resisting tension‐compression forces generated by the muscle during flexion the head. This element was previously known in several squamates, and we confirmed its presence in three additional squamate families: Gymnophthalmidae, Gekkonidae, and Pygopodidae. The evidence suggests that cranial sesamoids are a widespread character in squamates, and it is possible that this feature has been present since the origin of the group.     

Phosphorus uptake by bean nodules

As part of a breeding program to improve the nitrogen-fixing symbiosis between common bean (Phaseolus vulgaris) and Rhizobium etli, we developed a rapid screen for common bean accessions that preferentially nodulate with KIM5s, a high nitrogen fixing strain of R. etli. We constructed a mutant of KIM5s that did not fix nitrogen (Fix^-) but was otherwise indistinguishable from KIM5s. We screened plants for symptoms of nitrogen deficiency when grown in a Honduran soil containing indigenous common bean-nodulating rhizobia (10⁴ per gram) and KM6001, the Fix^- mutant of KIM5s (10⁴/seedling added 7 days after planting). Leaf color was scored on a scale of 1 to 5, in which 1 was dark green and 5 was bright yellow. Of 820 genetically diverse accessions of P. vulgaris screened, 51 were scored 1, 626 were scored 2 or 3, and 143 were scored 4 or 5. Selfed seed was produced from common bean plants of the accessions scored 1, 4 or 5. Twenty-four accessions that scored 1, and 58 that scored 4 or 5 were screened in soil containing indigenous rhizobia and the wild type KIM5s (Fix₊), and nodule occupancy was determined by antibiotic resistance. On the 24 common bean accessions that were scored 1, KIM5s occupied 0-6% of the nodules, on 26 of the accessions that were scored 4 or 5, KIM5s occupied 90%-100% of the nodules, and on the remaining 34 that scored 4 or 5, there was a distribution of nodule occupancy. Foliar color was highly correlated with nodule occupancy (r = 0.786,p = 0.01). The results indicate that the rapid visual screen using the Fix- mutant accurately identified common bean accessions that preferentially nodulate with the wild-type KIM5s (Fix⁺) strain in soil containing indigenous rhizobia. This screen will facilitate introduction of the preferential nodulation trait into superior cultivars and provides the foundation for studies of the genetic basis of preferential nodulation.     

Natural hybridization within seed sources of shortleaf pine (Pinus echinata Mill.) and loblolly pine (Pinus taeda L.)

Shortleaf and loblolly pine trees (n = 93 and 102, respectively) from 22 seed sources of the Southwide Southern Pine Seed Source Study plantings or equivalent origin were evaluated for amplified fragment length polymorphism (AFLP) variation. These sampled trees represent shortleaf pine and loblolly pine, as they existed across their native geographic ranges before intensive forest management. Using 17 primer pairs, a total of 96 AFLPs between shortleaf pine and loblolly pine were produced and scored on the sample trees and two control-pollinated F1 interspecies hybrids and their parents. In addition, the well known isocitrate dehydrogenase (IDH) isozyme marker was scored for all trees. IDH detected two putative hybrids among the loblolly pine samples and two among the shortleaf pine samples, while either 13 or 12 putative hybrids were detected using all AFLP markers and IDH and either NewHybrids or Structure software, respectively. Results of this study show that later generation hybrids can be reliably identified using AFLP markers and confirmed that IDH is not a definitive marker for detecting hybrids; that is, at least in some seed sources, the alternative species’ IDH allele resides in the source species. Based on all the markers, hybridization frequency varied geographically, ranging from 30% in an Arkansas seed source to 0% in several other seed sources. The hybridization level was higher in populations west of the Mississippi River than in populations east of the river; the shortleaf pine hybridization rates were 16.3% and 2.4% and the loblolly pine rates were 4.5% and 3.3%, west and east of the river, respectively. The results suggest that hybridization between these two species is significant but varies by seed source and species, and the potential for the unintended creation of hybrids should be considered in forest management decisions regarding both natural and artificial regeneration.     

Parity Influences the Demeanor of Sows in Group Housing

Across the globe, producers are moving from individual housing to group housing for sows during gestation. Producers typically group sows of a range of parities together, although the impacts are largely unknown. This study examined the behavioral expression at mixing for young, midparity, and older sows. Ten mixed-parity groups were filmed at mixing on a commercial piggery. One-minute clips were edited from continuous footage where focal sows of known parity could be identified, and scored for qualitative behavioral expression. Parity 2 and 6 sows were more calm/tired than Parity 4 sows, who were more active/energetic. Parity 2 sows were more curious/inquisitive than Parity 4 and 6 sows, who were more anxious/frustrated. Correlations between qualitative behavioral expression and activity indicated sows scored as more calm/tired spent a greater proportion of time standing, while sows scored as more active/energetic spent more time performing avoidance behavior. Different body language is likely to reflect physical or affective differences in how sows cope with mixing.     

Prediction of the Ease of Subdivision of Scored Tablets from Their Physical Parameters

At present, the ease of subdivision of scored tablets is estimated in vivo. In order to replace such in vivo testing and to develop a surrogate test which uses in vitro techniques, the association between physical parameters of scored tablets and their ease of subdivision was studied. The physical properties of 23 brands of scored tablets of which their ease of subdivision in vivo was known were established. Statistical modeling using a logistic regression model was used to fit the data and estimate the contribution of each physical parameter to the goodness of the fit. For scored oblong tablets, the critical parameters for their ease of subdivision are: diameter; diameter/width ratio; depth of score line and resistance to crushing. Criteria for each of these parameters were derived. All criteria need to be complied with to guarantee sufficient ease of subdivision of scored oblong tablets. For scored round tablets the critical parameters, in decreasing order of importance, for their ease of subdivision, are: resistance to crushing, diameter, score mark (one- or two-sided), and shape (flat or biconvex). A five-parameter predictive model was developed, showing excellent discrimination. For development, the proposed surrogate tests are sufficiently reliable. For release testing and stability studies, resistance to crushing of a scored tablet is a reliable predictor of its ease of subdivision.     

The Exploitation of Ungulate Bones in Homo neanderthalensis and Homo sapiens

Analysis of ungulate bones recovered from a number of Upper and Middle Palaeolithic sites in southern Italy revealed differences in the presence of anatomical elements. There is a lack of clear evidence of carnivore activities, and differences can be attributed to human activity. Indeed, these differences were probably due to different patterns of skeletal exploitation between Homo neanderthalensis and H. sapiens. Small limb bones (carpals, tarsals, sesamoids, long bone epiphyses and especially phalanges) are rarely found in Middle Palaeolithic deposits, but are abundant in the Upper Palaeolithic. The observation of unidentified bone fragments at these sites indicates that during the middle Palaeolithic, marrow extraction regarded essentially the treatment of long bones. First and second phalanges were not frequently used for this practice, but they were often fragmented by H. sapiens. Lack of these bones among the remains of meals of Neanderthal suggests that these bones were probably destroyed by their utilisation as fuel.     

A copia-like element in Pisum demonstrates the uses of dispersed repeated sequences in genetic analysis

A DNA sequence between two legumin genes in Pisum is a member of the copia-like class of retrotransposons and represents one member of a polymorphic and heterogeneous dispersed repeated sequence family in Pisum. This sequence can be exploited in genetic studies either by RFLP analysis where several markers can be scored together, or the segregation of individual elements can be followed after PCR amplification of specific members.     

Species-specific primers discriminate schistosome intermediate hosts: unambiguous PCR diagnosis of Bulinus forskalii group taxa (Gastropoda: Planorbidae)

The morphological definition of taxa has proved difficult within the Bulinus forskalii group, which includes intermediate hosts of medically important Schistosoma species in West Africa. Although B. forskalii and B. senegalensis transmit different schistosome species they are conchologically similar and their distributions overlap. Randomly amplified polymorphic DNA (RAPD) allows differentiation of sibling species in the genus Bulinus, but RAPDs are difficult to standardize, impairing their value as a taxonomic tool. Hence, RAPD products diagnostic for either B. senegalensis or B. forskalii from West Africa were cloned, sequenced and a panel of species-specific primers designed. Sequencing of RAPD products identified a homology in two apparently independent RAPD loci, a problem where RAPDs are indiscriminately scored for phylogenetic analyses. Specificity of primers was confirmed by widespread sampling throughout each species' range. This approach produced a simple, robust, unambiguous PCR-based species identification strategy for this difficult group.     

Development and morphological variation of the axial and appendicular skeleton in hylidae (Lissamphibia,Anura)

The axial and appendicular skeleton, the associated musculature and tendons form a functional system related to specific modes of locomotion in anurans. Many transformations in the structures linked with the locomotor function of the adult occur during larval stages and metamorphosis. In this study, we present the larval ontogeny and adult morphology of the axial and appendicular skeletons of 14 species of frogs in the family Hylidae with different locomotor modes and habitat uses. Among Hylidae, a diversity of shapes, locomotory types occurs (e.g., walker, swimmer, jumper, hopper) and different habitat types occupied (shrubby, terrestrial, aquatic, arboreal). Many elements complete differentiation at the end of metamorphosis; others, such as sesamoids, still show an incomplete development at that stage. Sixty seven characters were scored and optimized in an available phylogeny. Nine characters of developmental timing and adult osteology are optimized as synapomorphies of specific groups. Some characters appear to be related to the locomotor type (e.g., the sacro‐urostyle region configuration is highly linked with the jumping mode; nonexpanded diapophyses would related to aquatic habitat use). Nevertheless, the functional interpretations are quite particular to this family. Monophyletic clades are also groups with shared locomotory modes or habitat uses. Hence, the hypothesis of common ancestry or adaptation can be evaluated, taking into account the analysis level of the phylogenetic context, so that, when a character is inherited via common ancestry, it necessarily means that functional constraints could also be inherited. Here, we outline the basis for further work on: postmetamorphic development as a fundamental period for the complete differentiation of structures related to a full locomotor functionality; the biomechanical performance in relationship to the variation in ligaments and sesamoids; the importance of analyzing these topics within the frame of heterochrony. J. Morphol. 277:786–813, 2016. © 2016 Wiley Periodicals, Inc.     

Comparative osteology and phylogenetic systematics of fossil and living bony-tongue fishes (Actinopterygii, Teleostei, Osteoglossomorpha)

Several recent studies using analyses of morphological characters have addressed the interrelationships of Osteoglossomorpha, a group that sometimes is considered the living sister group of all other living teleosts. Many characters used in these studies were found to be poorly defined, to be coded incorrectly or illogically, or to display more variation than was described. The goal of this study is to address these concerns and contribute generally to knowledge of the morphology and systematic relationships of osteoglossomorphs. Analysis of 72 characters (65 informative) scored for 20 genera resulted in two most parsimonious cladograms (171 steps, CI = 0.6433, CI = 0.6139 excluding uninformative characters, HI = 0.3977, HI = 0.3861 excluding uninformative characters; RI = 0.7782; RC = 0.5006). Osteoglossomorpha is supported by both synapomorphies and homoplasies, although its monophyly was not truly tested in this analysis (only a single outgroup, Elops , was included in the analysis). The only difference in the topologies of these cladograms is in the position of ?Lycoptera (recovered as either the sister group of all other osteoglossomorphs sampled or of ?Eohiodon +Hiodon ). ?Ostariostoma is recovered as the sister group of all non‐hiodontiform osteoglossomorphs. Mormyrids are the sister group of notopterids + osteoglossids. This clade has not been found in other recent analyses. Mormyrids and notopterids usually are considered more closely related to each other than to any other group; characters not included here support this relationship and future consideration of these characters must be made. Although almost completely dichotomous, many nodes of the resulting trees lack rigorous support. For example, ?Palaeonotopterus is interpreted as the sister group of all mormyrids sampled, although for this taxon only 22% of characters could be scored. © 2003 The Linnean Society of London. Zoological Journal of the Linnean Society , 2003, 137 , 1?100.     

Appendicular skeleton in Bachia bicolor (Squamata: Gymnophthalmidae): osteology,limb reduction and postnatal skeletal ontogeny

The osteology of the appendicular skeleton and its postnatal development are described in Bachia bicolor, a serpentiform lizard with reduced limbs. The pectoral girdle is well developed and the forelimb consists of a humerus, ulna, radius, five carpal elements (ulnare, radiale, distal carpals 4–3, centrale), four metacarpals (II, III, IV, V) and phalanges (phalangeal formula X‐2‐2‐2‐2). In the hindlimb, the femur is small and slender, and articulates distally with a series of ossified amorphous and extremely reduced elements that correspond to a fibula, tibia and proximal and distal tarsals 4 and 3. The pelvic girdle consists of ischium, pubis and ilium, but its two halves are widely separated; the ilium is the least reduced element. We describe the ossification and development during postnatal skeletal ontogeny, especially of epiphyseal secondary centres, ossifications of carpal elements, apophyseal ossifications and sesamoids. Compared to other squamates, B. bicolor shows an overall reduction in limb size, an absence of skeletal elements, a fusion of carpal elements, an early differentiation of apophyseal centres, and a low number of sesamoids and apophyseal centres. These observations suggest that the reductions are produced by heterochronic changes during postnatal development and probably during embryonic development; therefore the appendicular skeleton exhibits a pattern of paedomorphic features.     

Analysis of Trends in Proportions with an Ordinally Scaled Determinant

In this paper the analysis of several proportions in a comparative study setting is discussed. The case of ordinal grouping variates is considered. F statistics are formulated to test for trend in the proportions over the scored values of the determinant variate. The null chi-square or F (t square) functions are presented separately for the unstratified and stratified analysis, and in either situation the corresponding functions with angular transformed proportions are also expressed. Generalizations to deal with the parameters in the nonnull range are outlined. Throughout, the intimate relation between the presented statistics and standard methods is pointed out.     

Brief repot: Interactions with infants by full siblings,paternal half-siblings,and nonrelatives in a captive group of rhesus macaques (Macaca mulatta)

Six mother-infant pairs in a group of captive rhesus monkeys (Macaca mulatta) were observed for six months. “Infant grabs” by others and mothers' resistance to grabs were scored. More full siblings grabbed infants than either paternal half-siblings or nonrelatives. Mothers resisted grabbing by more nonrelatives than by paternal half-siblings. Although the maternal effect suggested by full sib-infant interactions is expected, the paternal effect revealed by mothers' tolerance of paternal half-sibs, but not full siblings, over nonrelatives is unexpected.     

Coat condition of ringtailed lemurs,Lemur catta at Berenty Reserve,Madagascar: I. differences by age,sex, density and tourism, 1996–2006

An index of coat condition can be a non‐invasive tool for tracking health and stress at population level. Coat condition in ringtailed lemurs, Lemur catta, was recorded during September–November birth seasons of 1996, 1997, 1999, and 2001–2006 at Berenty Reserve, Madagascar. Condition was scored on a scale from 0: full, fluffy coat with guard hairs present, to 5: half or more of body hairless. Adult males did not differ overall from adult females. Coats were worse in adults than in 2‐year‐old subadults; 1‐year‐old juveniles were intermediate. Mothers and adult males lost coat condition as the season progressed: non‐mother females maintained condition. Years 1999–2002 scored better coats than either 1996–1997 or 2003–2006. Lemurs in high population density areas had worse coats than in natural forest, but tourist presence had less effect than density. Monitoring coat condition in an apparently healthy population reveals differences between population segments, and in a forest fragment with limited immigration or emigration it can track progressive changes, correcting impressions of progressive improvement or degradation over time. Above all it gives a baseline for response to climate changes or eventual pathology. Am. J. Primatol. 71:191–198, 2009. © 2008 Wiley‐Liss, Inc.     

Comparison of efficiency of direct observations by scuba diver and indirect observations via video camera for measuring reef-fish behaviour

The present study investigates how the humbug damselfish Dascyllus aruanus, subject of a large number of ecological, evolutionary and behavioural studies, responds to the presence of human observers (effect of scuba diver presence-absence) and how the method of data collection (directly by a scuba diver v. indirectly via video camera) may affect the quality of behavioural data. Scuba diver presence had only subtle effects on fish behaviour. The efficiency of the method of scoring fish behaviour depended on the behaviour under consideration: those behaviours that occur in close proximity to the corals were scored more effectively directly by a scuba diver while those that are performed in a more rapid or repetitive fashion were scored more effectively indirectly via video camera. These results provide a foundation for future behavioural research on D. aruanus and other fishes where scuba divers or video cameras are the prevalent means of data collection.     

Genetic control of yield related stalk traits in sugarcane

A major focus of sugarcane variety improvement programs is to increase sugar yield, which can be accomplished by either increasing the sugar content of the cane or by increasing cane yield, as the correlation between these traits is low. We used a cross between an Australian sugarcane variety Q165, and a Saccharum officinarum accession, IJ76-514, to dissect the inheritance of yield-related traits in the complex polyploid sugarcane. A population of 227 individuals was grown in a replicated field trial and evaluated over 3 years for stalk weight, stalk diameter, stalk number, stalk length and total biomass. Over 1,000 AFLP and SSR markers were scored across the population and used to identify quantitative trait loci (QTL). In total, 27 regions were found that were significant at the 5% threshold using permutation tests with at least one trait; individually, they explained from 4 to 10% of the phenotypic variation and up to 46% were consistent across years. With the inclusion of digeneic interactions, from 28 to 60% of the variation was explained for these traits. The 27 genomic regions were located on 22 linkage groups (LGs) in six of the eight homology groups (HGs) indicating that a number of alleles or quantitative trait alleles (QTA) at each QTL contribute to the trait; from one to three alleles had an effect on the traits for each QTL identified. Alleles of a candidate gene, TEOSINTE BRANCHED 1 (TB1), the major gene controlling branching in maize, were mapped in this population using either an SSR or SNP markers. Two alleles showed some association with stalk number, but unlike maize, TB1 is not a major gene controlling branching in sugarcane but only has a minor and variable effect.