Chondrocranium and cranial muscle morphology in Lysapsus and Pseudis tadpoles (Anura: Hylidae: Hylinae)

The chondrocranium and cranial muscles of Lysapsus limellum, Pseudis cardosoi, P. minuta and four subspecies of P. paradoxa (caribensis, occidentalis, paradoxa and platensis) are described. Lysapsus and Pseudis are related to the Hylidae by: (1) vertical processus anterolateralis of the larval crista parotica, and (2) presence of m. mandibulolabialis inferior and superior (the latter reversed in P. cardosoi). We confirm some larval synapomorphies previously proposed for the pseudids, except the m. subarcualis obliquus II having one head and the absence of copula anterior. We add three new features for the pseudids: (1) the distal end of ceratobranchiales III and IV projects towards either the capsula auditiva (Lysapsus) or the processus basicapsularis – new term – (Pseudis); (2) the arcus subocularis is twice as wide at the level of the processus ascendens as it is just posterior to the processus muscularis quadrati, and (3) the lateral corner of the processus articularis quadrati largely projects laterally. We diagnose Lysapsus larvae (the states of Pseudis in parentheses) as follows: (1) short processus pseudopterygoideus (long), (2) absence of lateral development of larval crista parotica (presence), (3) absence of commissura proximalis II (presence), (4) presence of processus lateralis hyalis – new term – (absence), (5) absence of processus basicapsularis (presence), (6) processus ascendens slightly curved along its entire extent (curved at the union with the basi cranii only), and (7) absence of m. tympanopharyngeus (presence).     

Wingstroke frequency of foraging and hovering bumblebees in relation to morphology and temperature

Abstract Wingstroke frequency, morphometries and thoracic temperatures of freely foraging bumblebees were examined in the field at ambient temperatures varying from 10 to 29^oC. Frequency was strongly correlated with morphometric parameters, particularly wing length, but was not correlated with either ambient or thoracic temperature. Magnitudes and scaling of frequency of foraging bees were comparable to values obtained for bees hovering in a closed chamber. These data indicate that frequency is primarily determined by morphometric characteristics which determine lift requirements and do not support the hypothesis that frequency is varied in response to environmental conditions as a means of in-flight thermoregulation.     

The genetic basis of early‐life morphological traits and their relation to alternative male reproductive tactics in Atlantic salmon

Although heritability estimates for traits potentially under natural selection are increasingly being reported, their estimation remains a challenge if we are to understand the patterns of adaptive phenotypic change in nature. Given the potentially important role of selection on the early life phenotype, and thereby on future life history events in many fish species, we conducted a common garden experiment, using the Atlantic salmon (Salmo salar L.), with two major aims. The first objective is to determine how the site of origin, the paternal sexual tactic and additive genetic effects influence phenotypic variation of several morphological traits at hatching and emergence. The second aim is to test whether a link exists between phenotypic characteristics early in life and the incidence of male alternative tactics later in life. We found no evidence of a site or paternal effect on any morphological trait at hatching or emergence, suggesting that the spatial phenotypic differences observed in the natural river system from which these fish originated are mainly environmentally driven. However, we do find significant heritabilities and maternal effects for several traits, including body size. No direct evidence was found correlating the incidence of precocious maturation with early life characteristics. We suggest that under good growing conditions, body size and other traits at early developmental stages are not reliable cues for the surpassing of the threshold values associated with male sexual development.     

Pollen morphology of the Thymelaeaceae in relation to its taxonomy

 Pollen morphology of the four subfamilies of Thymelaeaceae sensu Domke (1934) was examined using LM, SEM and TEM. The variation of the exine architecture allows to distinguish four pollen types and three subtypes. Distribution of pollen types proves to be widely correlated with the occurrence of characters from wood anatomy and flower morphology. If pollen types are connected with subfamilies sensu Domke (1934), Gonystyloideae, Thymelaeoideae and Synandrodaphnoideae are stenopalynous, whereas Aquilarioideae are eurypalynous. Based on pollen morphology as well as on other characters it is evident that Aquilarioideae are not monophyletic. Its genera Aquilaria and Gyrinops are more closely related to Thymelaeoideae and Synandrodaphnoideae than to other genera of Aquilarioideae sensu Domke (1934). The remaining genera of Aquilarioideae Deltaria, Solmsia and Lethedon are most similar to Gonystyloideae and therefore are included in this subfamily, as it was suggested by Airy Shaw (1979). Furthermore, palynological and other characters favour the transfer of Octolepis from Aquilarioideae to Gonystyloideae. The re-circumscribed Aquilarioideae together with Thymelaeoideae and Synandrodaphnoideae are shown to form a monophyletic group. Received August 8, 2001 Accepted December 7, 2001     

Development of the nidicolous tadpoles of Eupsophus emiliopugini (Anura: Cycloramphidae) until metamorphosis,with comments on systematic relationships of the species and its endotrophic developmental mode

Vera Candioti, M.F., Nuñez, J.J. and Úbeda, C. 2011. Development of the nidicolous tadpoles of Eupsophus emiliopugini (Anura: Cycloramphidae) until metamorphosis, with comments on systematic relationships of the species and its endotrophic developmental mode. —Acta Zoologica (Stockholm) 92 : 27–45. Species of Eupsophus are unique within Alsodinae in having nidicolous tadpoles. They are characterized by traits typical of generalized exotrophic (e.g., oral disc and spiracular tube) and endotrophic larvae (e.g., scant pigmentation and large hind limbs). The larval morphology and development of E. emiliopugini, including external, buccal, and musculoskeletal features, is described herein. Like the larvae of other alsodines, these larvae have four lingual and four infralabial papillae, quadratoethmoid process, and an m. rectus cervicis with a double insertion. Among the traits exclusive to the genus are: the absence of the pseudopterygoid process and quadrato‐orbital commissure; presence of the m. subarcualis rectus I with two slips; and presence of the m. subarcualis rectus II–IV inserting on Ceratobranchial II. The development and metamorphosis of Eupsophus include some characters that develop later (e.g., degeneration of mouthparts and chondrocranium with minimum calcification), characters that develop earlier (e.g., hind‐limb appearance and jaw and suspensorium ossification), and characters that develop at the same time (e.g., most external features and cranial muscles) than in most exotrophic species. Some distinctive characters (third lower labial ridge absent, general configuration of the hyobranchial skeleton, skeletal development with retention of larval traits) resemble those of other endotrophic species, and the precocious ossification of jaws and suspensorium is shared with several direct‐developing species among recent amphibians.     

Comparative study of gill neuroepithelial cells and their innervation in teleosts and Xenopus tadpoles

Peripheral O₂ chemoreceptors initiate adaptive cardiorespiratory responses to hypoxia in vertebrates. Morphological and physiological evidence suggests that, in fish, neuroepithelial cells (NECs) of the gill perform this role. We conducted a comparative examination in three species of teleosts (zebrafish, goldfish and trout) and larvae of the amphibian Xenopus laevis, using whole-mount gill preparations and confocal immunofluorescence, to elucidate the distribution, morphology and innervation of gill NECs. Nerve fibres were immunolabelled with the neuronal marker zn-12 and were associated with serotonin-immunoreactive NECs in the gills of all species tested. With the exception of trout, innervated NECs were present on all gill arches in the filaments and respiratory lamellae in fish and on homologous structures in Xenopus (i.e. gill “tufts”, including respiratory terminal branches). Thus, the distribution and innervation of NECs of the internal gills of amphibians and teleosts are relatively well conserved, suggesting an important role for gill NECs as O₂ chemoreceptors in aquatic vertebrates. Furthermore, the size and density of gill NECs is variable among teleosts and developmental stages of Xenopus larvae and may be dependent on general gill dimensions or environmental conditions. This report constitutes the first comparative study of gill NECs in fish and amphibians and highlights the significance of gill NECs as an evolutionary model for studying O₂ sensing in vertebrates. We acknowledge the Natural Sciences and Engineering Research Council (NSERC) of Canada for funding through an operating grant to C.A.N., and the NSERC and the Ontario Graduate Scholarship (OGS) program for postgraduate scholarships to M.G.J.     

Developmental kinetics of the first cell cycles of bovine in vitro produced embryos in relation to their in vitro viability and sex

The development of bovine IVP-embryos was observed in a time-lapse culture system to determine cell cycle lengths of 1) embryos that developed into compact morulae (CM) or blastocysts (BL) within 174 h after insemination (viable), 2) embryos that arrested during earlier stages (nonviable) and 3) male and female embryos. In 4 replicates, inseminated oocytes were cultured on a microscope stage in 3 to 4 groups on a granulosa cell monolayer in supplemented TCM 199. Images were sequentially recorded and stored at 30-min intervals. All embryos that could be identified throughout the culture period were included (n=392), and the times of cleavage events noted. After culture, 100 CM or BL were randomly selected for sexing by PCR. BL developed equally well in the time-lapse and control culture systems (36 vs 38%). The respective lengths of the first 4 cell cycles of viable embryos were 32.0 ± 3.9, 8.8 ± 1.6, 10.8 ± 4.7 and 47.7 ± 11.8 h. The subsequent intervals between the 9- to 16-cell, early morula, CM and BL stages lasted 16.2 to 18.2 h. Blastomeres of 2-,4- and 8-cell embryos cleaved asynchronously with <1, 2.6 ± 2.5 and 9.2 ± 4.5 h intervals, respectively, between the first and last blastomere to cleave. The interval from insemination to tight compaction and formation of a blastocoel was 128.4 ± 10.7 and 145.8 ± 12.5 h, respectively. The first 3 cell cycles were approximately 3 h shorter (P < 0.1) while the fourth cycle was 5 h shorter (P = 0.06) for the viable vs nonviable embryos. On this basis it was possible to define time windows in which the proportion of viable 2-, 3- to 4-, 5- to 8- and 9- to 16-cell embryos were at their highest. No differences were found between the cleavage intervals of male and female embryos. We conclude 1) that the time-lapse culture system allows for detailed observation of the developmental kinetics of several embryo groups at the same time, and 2) that these embryos can be manipulated at the end of culture, thus allowing a linkage between early cleavage events and other developmental parameters such as embryo sex or viability after transfer.     

Thiophene accumulation in relation to morphology in roots of Tagetes patula

Roots of marigold (Tagetes patula L.) accumulate thiophenes, heterocyclic sulfurous compounds with strong biocidal activity. In detached roots cultured in vitro, the thiophene content was 5 mol·(g fresh weight)^-1 which is 25-times higher than in roots attached to the plant. In roots derived from tissues transformed by Agrobacterium tumefaciens and A. rhizogenes, the morphology and thiophene content varied with the bacterial strain used. Transformation stimulated the elongation of the root tips and the formation of lateral roots but lowered the thiophene level to 20–50% relative to the concentration in untransformed detached roots. A negative correlation was found between the number of laterals in a root system and the thiophene content. Extensive branching and a decrease in thiophene accumulation was evoked in untransformed roots by indole-3-acetic acid (1–10 mol·l^-1) added to the medium. Within the roots, the highest thiophene concentrations were found in the tips. The results indicate that auxin directly or indirectly plays a role in the regulation of the thiophene level in root tips.Abbreviations B5 Gamborg's B5 medium - IAA Indole-3-acetic acid     

Geographical and seasonal differences in morphology and dynamics of the coccolithophore Calcidiscus leptoporus

Calcidiscus leptoporus is a cosmopolitan coccolithophore species, composed of three morphotypes characterised by differences in morphology and size. The seasonal dynamics of this species have been studied in four sediment trap and plankton time series covering different biogeographic settings. Investigated parameters were: variations in absolute and relative abundances of the three morphotypes, average size variations of the C. leptoporus assemblages, and intra-morphotype size variations. For each time series, and for the complete data set, the relationship between C. leptoporus dynamics and some environmental parameters was investigated. Seasonal variations can be recognised in the four time series, but the biogeographic pattern governing this seasonality is complex. The two best documented morphotypes show comparable seasonal fluctuations in absolute abundances, mainly co-varying with temperature and related factors such as water mixing. However, their relative abundances change with varying nutrient contents in the surface water masses, suggesting slight differences in their respective ecological preferences. Average size of the C. leptoporus assemblage provides information about the morphotype composition and allows a comparison of the seasonal variations observed in the present study and Holocene geographic patterns reported in the literature. Additionally, intra-morphotype size variations might be related to environmental changes.     

Anthropometric aspects of hand morphology in relation to sex and to body mass in a Turkish population sample

The hand is not only one of the principal structures related to motor function but is also essential for tactile sensations. The genetic endowment of an individual plays an important role in the development and differentiation of the hands. Certain features of hands are known to be sexually dimorphic and body morphology may also affect hand morphology. The aim of this study was to evaluate the anthropometric aspects of the hand in terms of its overall morphology and shape in relation to sex.     

Electrical potential differences in cells of barley roots and their relation to ion uptake

Single cell electropotentials of barley (Hordeum vulgare L., cv. `Compana') root cortex were measured at different external concentrations of KCl in the presence of Ca²⁺. The roots were low in salt from seedlings grown on 0.5 mm aerated CaSO₄ solution. Thus, the conditions were equivalent to those used to define the dual mechanisms found with radioactive tracer-labeled ion uptake. In 0.5 mm CaSO₄ alone, there is an increase with time of cell negativity from about -65 millivolts 15 minutes after cutting segments to about -185 millivolts in 6 to 8 hours. Two possible hypotheses, not mutually exclusive, are offered to explain this aging effect: that cutting exposes plasmodesmata which are leaky initially but which seal in time, and that some internal factors, e.g., hormones diffusing from the apex, have a regulatory effect on the cell potential, an influence which becomes dissipated in isolated segments and permits the development of a higher potential difference. In any case changes in selective ion transport must be involved. The cell potentials at KCl concentrations above 2.0 mm are more negative than would be expected for a passive diffusion potential. It is suggested that this discrepancy may be due to an electrogenic pump or to a higher K⁺ concentration in the cytoplasm than in the remainder of the cell, or perhaps to both. Whether there is a clear relationship between cell potential and mechanisms 1 and 2 of cation transport depends upon whether the cell potentials of freshly cut or of aged tissue represent the values relevant to intact roots.     

Functional mechanisms of an inducible defence in tadpoles: morphology and behaviour influence mortality risk from predation

In many amphibian larvae a suite of morphological and behavioural characters varies together in an induced defence against predators, but it remains unclear which features are functionally related to defence. We independently manipulated behaviour and morphology in tadpoles of Hyla versicolor and assessed their consequences for swimming performance and predator escape. Data on burst swimming showed that tadpoles which accelerated rapidly were elongate, with shallow bodies and tails. Predator escape was measured by exposing tadpoles to predators (larval Anax dragonflies or larval Ambystoma salamanders) and recording time until death. Tadpoles were first reared for 30 days in ponds containing either caged Anax or no predators; individuals responded to predators by developing large brightly coloured tails and short bodies. We placed tadpoles of both morphological phenotypes into plastic tubs, and manipulated their behaviour using food and chemical cues from predators. Mortality risk experienced by the predator‐induced phenotype was about half that of the no‐predator phenotype, and risk increased with time spent swimming. An interaction between morphology and behaviour arose because increasing activity caused higher risk for tadpoles with deep tail fins but not shallow tail fins.     

Inter- and intraspecific variations in limb morphology of some south-east Australian cladocerans: Implications for particle capture

Intra- and interspecific variation in the intersetular distance (i.s.d.) of some southern Australian cladocerans was examined. The seasonal range of i.s.d. inDaphnia carinata adults (2.34±0.07 mm) was 0.17–0.25 μm. I.s.d. increased with increasing body size forD. carinata andD. thomsoni. Variation in i.s.d. between nine adult cladoceran taxa (several of which coexisted) also was examined; significant differences did occur, but the size range was small (0.14 to 0.58 μm). The possibility that intersetular distances are an index of niche separation based upon the capture of different particle sizes is discussed.