Footfall patterns and interlimb co-ordination in opossums (Family Didelphidae): evidence for the evolution of diagonal-sequence walking gaits in primates

Most primates typically use a diagonal-sequence footfall pattern during walking. This footfall pattern, which is unusual for mammals, is believed to have originated in ancestral primates in association with the use of grasping extremities for movement and foraging on thin, flexible branches. This theory was tested by comparing gait parameters between the grey short-tailed opossum Monodelphis domestica and the woolly opossum Caluromys philander , two didelphid marsupials that are strongly differentiated in grasping morphology of the extremities and in their reliance on foraging strategies involving thin branches. One hundred and thirty gait cycles were analysed quantitatively from videotapes of subjects moving quadrupedally on a runway and on poles of different diameters (7 and 28 mm). Duty factor (i.e. duration of the stance phase as a percentage of the stride period) for the forelimb and hindlimb, as well as diagonality (i.e. phase relationship between the forelimb and hindlimb cycles), were calculated for each of these symmetrical gait cycles. We found that the highly terrestrial Monodelphis , like most other non-primate mammals, relies primarily on lateral-sequence walking gaits on both runway and poles, and has relatively higher forelimb duty factors. Like primates, the highly arboreal Caluromys uses primarily diagonal-sequence walking gaits on the runway and pole, with relatively higher hindlimb duty factors and diagonality. The fact that the woolly opossum, a marsupial with primate-like feet that moves and forages mainly on thin branches, uses primarily diagonal-sequence gaits when walking supports the view that primate gaits evolved to meet the demands of locomotion on narrow supports. This also demonstrates the functional role of a grasping foot, in association with relatively higher hindlimb duty factors, protraction, and substrate reaction forces, in the production of such walking gaits.     

Kinematic Analysis and Experimental Verification on the Locomotion of Gecko

This paper presents a kinematic analysis of the locomotion of a gecko,and experimental verification of the kinematicmodel.Kinematic analysis is important for parameter design,dynamic analysis,and optimization in biomimetic robot research.The proposed kinematic analysis can simulate,without iteration,the locomotion of gecko satisfying the constraint conditionsthat maintain the position of the contacted feet on the surface.So the method has an advantage for analyzing the climbing motionof the quadruped mechanism in a real time application.The kinematic model of a gecko consists of four legs based on 7-degreesof freedom spherical-revolute-spherical joints and two revolute joints in the waist.The motion of the kinematic model issimulated based on measurement data of each joint.The motion of the kinematic model simulates the investigated real gecko’smotion by using the experimental results.The analysis solves the forward kinematics by considering the model as a combinationof closed and open serial mechanisms under the condition that maintains the contact positions of the attached feet on the ground.The motions of each joint are validated by comparing with the experimental results.In addition to the measured gait,three othergaits are simulated based on the kinematic model.The maximum strides of each gait are calculated by workspace analysis.Theresult can be used in biomimetic robot design and motion planning.     

Discovery of a new fossil soldier beetle in Eocene Baltic amber,with the establishment of the new tribe Cacomorphocerini

Eocene forest ecosystems can be considered as rich biodiversity hotspots regarding soldier beetles (family Cantharidae). Paleogene European ambers, for instance, comprised many genera that are still extant in Europe, but also extinct forms and lineages such as the tribe established herein, or the tribe Mimoplatycini Kazantsev, 2013 that mimics the lycids. In this note, the authors describe Cacomorphocerus wiszniewskii sp. nov., and the new tribe Cacomorphocerini tri. nov. is proposed for Cacomorphocerus Schaufuss, 1892 and Sucinocantharis Ku?ka and Kania, 2010. The new tribe is characterized by antennae with 12 or 16 articles, with saucer-shaped or dilated central antennomeres and is distributed in Eocene Baltic and Rovno amber. Furthermore, Cacomorphocerus is transferred from the subfamily Dysmorphocerinae Brancucci, 1980 to Cantharinae Imhoff, 1856.     

Web-building management in an orb-weaving spider, Zygiella x-notata: influence of prey and conspecifics

According to optimal foraging theory, spiders should adapt their web building to environmental variations. Until now, there was no data on the influence of simultaneous information coming from different environmental factors on web building behaviour. Under laboratory conditions, we studied the behaviour of Zygiella x-notata in the presence of prey, conspecifics, or both simultaneously. There was a stimulating effect of prey, but web building was not affected by the presence of conspecifics. When spiders and prey were present simultaneously, the effect was similar to that of prey alone; it seemed that there was no interactive influence of both factors. We discussed about the use of environmental information by spiders in foraging behaviour.     

Role of membrane colchicine binding proteins in the transmission of prolactin message to casein genes in the rabbit mammary gland

Previous work demonstrated that tubulin binding drugs specifically inhibit the capacity of prolactin to initiate casein and DNA synthesis in the mammary cell. It was concluded that microtubules or other tubulin containing cellular structures were involved in the transmission of the prolactin message to genes. In the present work, it is shown that griseofulvin, an antimitotic drug which alters microtubule structure and function, does not prevent prolactin actions. Autoradiographic studies showed that [3H]colchicine binds preferentially to plasma and Golgi membranes in the mammary cell. Short term cultures of mammary explants with [3H]colchicine demonstrated that the labelled drug binds to membranous cellular structures which were isolated from explants at the end of the culture. Fractions containing plasma and Golgi membranes contained the highest amount of radioactivity. Solubilisation of the membranes by Triton X-100 dissociated the [3H]colchicine from the prolactin receptors as judged by a chromatography of the soluble fraction on a Sepharose 6 B column. On the column, the labelled colchicine remains associated with a molecular entity which may be free tubulin. In all cases, the binding of [3H]colchicine was greatly attenuated by an excess of unlabelled colchicine but was only slightly affected by the competition with lumicolchicine. These results suggest that mammary membranes contain tubulin and that binding of drugs to this molecule inhibits the generation of the prolactin second messengers eliciting the hormonal actions in the mammary cell. This also suggests that microtubules are probably not involved in the mechanism of prolactin action.     

Biochemical and biophysical characterization of collagen in Tenebrio molitor L. (Coleoptera, Tenebrionidae)

The collagen from the mesenteric sheath of the tenebrionid insect Tenebrio molitor was extracted by limited pepsin digestion and purified. This collagen was characterized using CM-cellulose chromatography, sodium-dodecylsulfate disc-gel electrophoresis and aminoacid analysis. This molecule was found to be assembled from three identical alpha chains and could be represented by the formula (alpha) 3. The amino acid composition is characteristic of collagen (one-third glycine, high iminoacid content), with high content of hydroxylysine and low content of alanine. Cyanogen bromide digests of these chains indicated that they are not related to any of the known invertebrate or vertebrate chains of interstitial collagens. The molecular weight (M = 280000D) and length (290 nm) were typical, and the banding patterns of the segment-long-spacing crystallites (SLS) and of the reconstitued fibrils were very similar to type I collagen. The denaturation temperature (Td) was 30.7 degrees C and correlated with the total pyrrolidine content as observed in other collagens (von Hippel & Wong's relation). It was concluded that the collagen from this insect showed the classical biochemical and biophysical features of other invertebrate interstitial "primitive" collagens.     

The origins of the strategy of codon use

We analyzed the DNA sequences taking as an elementary pattern segments of increasing length from the codon to the gene. We have thus been able to identify part of the constraints from which originates the use of the code degeneracy in each gene. Our results show that the strategy of codon use is not solely related to the translation apparatus characteristics.     

A new rheophytic species of Euceraea (Flacourtiaceae) from Sierra de la Neblina, Venezuela

Euceraea rheophytica is newly described and illustrated. It differs from the two other species in the genus, E. nitida and E. sleumeriana, in its much smaller and narrower leaves and in its smaller, spicate (vs. branched) inflorescences. It is known only from frequently flash-flooded riverbanks in the large, central canyon of the Sierra de la Neblina massif in southernmost Venezuela.     

System analysis and nucleic acid sequence banks

The mass of published nucleic acid sequence data has required the design of several computerized data bases. We show that this activity is related to the methodology of System Analysis and that data bases are a means of modeling biological knowledge. As an example, the ACNUC data base we have created is presented.     

A case of reversal in Paralichthys orbignyanus a shallow-water flounder from the south-western Atlantic

A right-sided Paralichthys orbignyanus was reported for the first time in the western South Atlantic. Some morphometric peculiarities were noticed in the reversed specimen compared with the normal flatfish of the same species.     

Three-dimensional analysis of horse and human gaits in therapeutic riding

Therapeutic horse riding or hippotherapy is used as an intervention for treating individuals with mental and physical disabilities. Equine-assisted interventions are based on the hypothesis that the movement of the horse's pelvis during horseback riding resembles human ambulation, and thus provides motor and sensory inputs similar to those received during human walking. However, this hypothesis has not been investigated quantitatively and qualitatively. This study aimed to verify the hypothesis by conducting a three-dimensional analysis of the horse's movements while walking and human ambulation. Using four sets of equipments, we analysed the acceleration patterns of walking in 50 healthy humans and 11 horses. In addition, we analysed the exercise intensity by comparing the heart rate, breathing rate, and blood pressure of 127 healthy individuals before and after walking and horse riding. The acceleration data series of the stride phase of horse walking were compared with those of human walking, and the frequencies (in Hz) were analysed by Fast Fourier transform.The acceleration curves of human walking overlapped with those of horse walking, with the frequency band of human walking corresponding with that of horse walking. Exercise intensity, as measured by the heart rate and breathing rate, was not significantly different between horse riding and human walking. The levels of diastolic blood pressure were slightly higher during horse riding than during walking, but were lower during both conditions compared with those in normal conditions (P < 0.01). The present study shows that, although not completely matched, the accelerations of the horse and human walking are comparable quantitatively and qualitatively. Horse riding at a walking gait could generate motor and sensory inputs similar to those produced by human walking, and thus could provide optimum benefits to persons with ambulatory difficulties.     

A new species of Illicium subsection Parviflora (Illiciaceae) from the Massif de la Hotte, Haiti

Illicium hottense, a new species, is here described from the floristically diverse Massif de la Hotte of southern Haiti. It is compared to related species, especiallyI. ekmanii, with which it has previously been confused.Illicium hottense andI. ekmanii are members ofIllicium subsectionParviflora, a group that comprises four species, all endemic to peninsular Florida (I. parviflorum) or the Greater Antilles: Cuba (I. cubense) and Hispaniola (I. ekmanii, andI. hottense). The subsection is characterized by its distinctive laminar-carnose, ovoid stamens; all have trisyncolpate pollen.Illicium hottense is similar toI. ekmanii andI. parviflorum in having flowers with ten to thirteen carpels and six to less commonly eight stamens, but differs from both in its strongly papillose outer tepals and consistently acute leaves. In addition, its leaves lack the strong anise fragrance ofI. parviflorum. Finally, molecular data provide support for recognizingI. hottense as a species distinct fromI. ekmanii.     

Ontogenetic changes in protein dephosphorylating activity of the cytosolic compartment of rat erythrocytes

Total casein phosphatase activity of erythrocytes from one-month-old rats was separated by DEAE-cellulose chromatography into three peaks--E1, E2 and E3--and only into two peaks--E1 and E3--when the erythrocyte donors were six- and 12-month-old rats. The activity of E1 (Mr 330 K) decreased continuously in erythrocytes during the first year of postnatal life. E2 (Mr 230 K) also decreased and completely disappeared from the cells of 12-month-old rats. E3 (Mr 180 K) was the dominant molecular form in the cytosol of erythrocytes during the first year of life. It decreased only up to six months of life. In this form E3 seems to be cooperative with respect to the substrate and to inhibitor molecules. The decrease of its kinetic parameters (Vmax and K0.55) was also found during postnatal ontogenesis. E3 isolated from erythrocytes of older rats (6 and 12 months) was more susceptible to inhibitory effect of pyrophosphate and to the change of ionic strength of eluting buffer than the enzyme from one-month-old rats. 0.2 mol.1(-1) NaCl lowered Mr of E3 phosphatase from 180 K to 128 K only in older rats.     

A knowledge-driven agent-centred framework for data mining in EMG

In this paper, we present a multi-agent framework for data mining in electromyography. This application, based on a web interface, provides a set of functionalities allowing to manipulate 1000 medical cases and more than 25,000 neurological tests stored in a medical database. The aim is to extract medical information using data mining algorithms and to supply a knowledge base with pertinent information. The multi-agent platform gives the possibility to distribute the data management process between several autonomous entities. This framework provides a parallel and flexible data manipulation.     

A new protein from human plasma lipoproteins: isolation and partial characterization of apolipoprotein G]

A new apolipoprotein has been identified in VHDL1 and in HDL. This protein is immunologically distinct from already isolated apoproteins. It was isolated by column chromatography on hydroxylapatite. In polyacrylamide gel electrophoresis, its mobility is very close to that of apo D. The amino acid composition differs from those of the well characterized polypeptides of the human plasma lipoproteins. It contains glucosamine. The apparent molecular weight is 72 000 +/- 2 000 in the presence and absence of reducing agent. According to the ABCDEF nomenclature, this protein can be named apolipoprotein G (apo G). It is present in a lipoprotein distinct from the lipoproteins A and D among the VHDL1 : this new lipoprotein can be named lipoprotein G (LPG).     

Actin-based motility as a self-organized system: mechanism and reconstitution in vitro

Site-directed actin polymerisation in response to signalling is responsible for the formation of cell protrusions. These elementary 'actin-based motility processes' are involved in cell locomotion, cell metastasis, organ morphogenesis and microbial pathogenesis. We have reconstituted actin-based propulsive movement of particles of various sizes and geometries (rods, microspheres) in a minimum motility medium containing five pure proteins. The ATP-supported treadmilling of actin filaments, regulated by Actin Depolymerizing Factor (ADF/cofilin), profilin and capping proteins provides the thermodynamic basis for sustained actin-based movement. Local activation of Arp2/3 complex at the surface of the particle promotes autocatalytic barbed end branching of filaments, generating a polarized arborescent array. Barbed end growth of branched filaments against the surface generates a propulsive force and is eventually arrested by capping proteins. Understanding the mechanism of actin-based movement requires elucidation of the biochemical properties and mode of action of Arp2/3 complex in filament branching, in particular the role of ATP binding and hydrolysis in Arp2/3, and a physical analysis of the movement of functionalised particles. Because the functionalisation of the particle by an activator of Arp2/3 complex (N-WASP or the Listeria protein ActA) and the concentrations of effectors in the medium are controlled, the reconstituted motility assay allows an analysis of the mechanism of force production at the mesoscopic and molecular levels.