Convergence of macroscopic tongue anatomy in ruminants and scaling relationships with body mass or tongue length

Various morphological measures demonstrate convergent evolution in ruminants with their natural diet, in particular with respect to the browser/grazer dichotomy. Here, we report quantitative macroanatomical measures of the tongue (length and width of specific parts) of 65 ruminant species and relate them to either body mass (BM) or total tongue length, and to the percentage of grass in the natural diet (%grass). Models without and with accounting for the phylogenetic structures of the dataset were used, and models were ranked using Akaike's Information Criterion. Scaling relationships followed geometric principles, that is, length measures scaled with BM to the power of 0.33. Models that used tongue length rather than BM as a body size proxy were consistently ranked better, indicating that using size proxies that are less susceptible to a wider variety of factors (such as BM that fluctuates with body condition) should be attempted whenever possible. The proportion of the freely mobile tongue tip of the total tongue (and hence also the corpus length) was negatively correlated to %grass, in accordance with concepts that the feeding mechanism of browsers requires more mobile tongues. It should be noted that some nonbrowsers, such as cattle, use a peculiar mechanism for grazing that also requires long, mobile tongues, but they appear to be exceptions. A larger corpus width with increasing %grass corresponds to differences in snout shape with broader snouts in grazers. The Torus linguae is longer with increasing %grass, a finding that still warrants functional interpretation. This study shows that tongue measures covary with diet in ruminants. In contrast, the shape of the tongue (straight or “hourglass‐shaped” as measured by the ratio of the widest and smallest corpus width) is unrelated to diet and is influenced strongly by phylogeny. J. Morphol. 277:351–362, 2016. © 2015 Wiley Periodicals, Inc.     

A case of non-scaling in mammalian physiology? Body size, digestive capacity, food intake, and ingesta passage in mammalian herbivores

As gut capacity is assumed to scale linearly to body mass (BM), and dry matter intake (DMI) to metabolic body weight (BM(0.75)), it has been proposed that ingesta mean retention time (MRT) should scale to BM(0.25) in herbivorous mammals. We test these assumptions with the most comprehensive literature data collations (n=74 species for gut capacity, n=93 species for DMI and MRT) to date. For MRT, only data from studies was used during which DMI was also recorded. Gut capacity scaled to BM(1.06). In spite of large differences in feeding regimes, absolute DMI (kg/d) scaled to BM(0.76) across all species tested. Regardless of this allometry inherent in the dataset, there was only a very low allometric scaling of MRT with BM(0.14) across all species. If species were divided according to the morphophysiological design of their digestive tract, there was non-significant scaling of MRT with BM(0.04) in colon fermenters, BM(0.08) in non-ruminant foregut fermenters, BM(0.06) in browsing and BM(0.04) in grazing ruminants. In contrast, MRT significantly scaled to BM(0.24) (CI 0.16-0.33) in the caecum fermenters. The results suggest that below a certain body size, long MRTs cannot be achieved even though coprophagy is performed; this supports the assumption of a potential body size limitation for herbivory on the lower end of the body size range. However, above a 500 g-threshold, there is no indication of a substantial general increase of MRT with BM. We therefore consider ingesta retention in mammalian herbivores an example of a biological, time-dependent variable that can, on an interspecific level, be dissociated from a supposed obligatory allometric scaling by the morphophysiological design of the digestive tract. We propose that very large body size does not automatically imply a digestive advantage, because long MRTs do not seem to be a characteristic of very large species only. A comparison of the relative DMI (g/kg(0.75)) with MRT indicates that, on an interspecific level, higher intakes are correlated to shorter MRTs in caecum, colon and non-ruminant foregut fermenters; in contrast, no significant correlation between relative DMI and MRT is evident in ruminants.     

Comparative omasum anatomy in ruminants: Relationships with natural diet,digestive physiology,and general considerations on allometric investigations

The omasum is the third forestomach compartment of pecoran ruminants. It is assumed that the re-absorption of fluid present in the forestomach digesta (that facilitates particle sorting, digestion, and harvest of microbes) is its main function, so that less diluted digesta is submitted to enzymatic digestion in the lower digestive tract. Here, we evaluate measures of omasum size (representing 84 ruminant species in the largest data set) against body mass and proxies of the natural diet (%grass) or forestomach physiology (fluid throughput), using phylogenetically controlled models. The origin of specimens (free-ranging or captive) did not have an effect in the data set. Models with the best support invariably either included %grass or a physiology proxy in addition to body mass. These effects were not necessarily additive (affecting the intercept of the allometric regression), but often indicated a change in the allometric body mass-exponent with diet or physiology. Only models that allowed an influence on the allometric exponent yielded basic exponents compatible with predictions derived from geometry. Species that include more grass in their natural diet, or that have a “cattle-type” physiology marked by a high forestomach fluid throughput, generally have larger omasa. However, the existence of outliers, as well as the overall data pattern, suggest that this is not an obligatory morphophysiological condition. Circumstantial evidence is presented leading to the hypothesis that the comparatively small and less complex omasa of “moose-type” species do not necessarily represent an “original” state, but may be derived from more complex states by ontogenetic reduction and fusion of omasal laminae.     

Higher masseter muscle mass in grazing than in browsing ruminants

Using cranioskeletal measurements, several studies have generated evidence that grazing ruminants have a more pronounced mastication apparatus, in terms of muscle insertion areas and protuberances, than browsing ruminants, with the resulting hypothesis that grazers should have larger, heavier chewing muscles than browsers. However, the only investigation of this so far [Axmacher and Hofmann (J Zool 215:463-473, 1988)] did not find differences between ruminant feeding types in the masseter muscle mass of 22 species. Here, we expand the dataset to 48 ruminant species. Regardless of phylogenetic control in the statistical treatment, there was a significant positive correlation of body mass and masseter mass, and also a significant association between percent grass in the natural diet and masseter mass. The results support the concept that ruminant species that ingest more grass have relatively larger masseter muscles, possibly indicating an increased requirement to overcome the resistance of grass forage. The comparative chewing resistance of different forage classes may represent a rewarding field of ecophysiological research.     

Is there an influence of body mass on digesta mean retention time in herbivores? A comparative study on ungulates

The relation between body mass (BM) and digesta mean retention time (MRT) in herbivores was the focus of several studies in recent years. It was assumed that MRT scaled with BM(0.25) based on the isometric scaling of gut capacity (BM(1.0)) and allometric scaling of energy intake (BM(0.75)). Literature studies that tested this hypothesis produced conflicting results, arriving sometimes at higher or lower exponents than the postulated 0.25. This study was conducted with 8 ruminants (n=2-6 per species) and 6 hindgut fermenting species/breeds (n=2-6, warthog n=1) with a BM range of 60-4000 kg. All animals received a ration of 100% grass hay with ad libitum access. Dry matter intake was measured and the MRT was estimated by the use of a solute and a particle (1-2 mm) marker. No significant scaling of MRT(particle) with BM was observed for all herbivores (32 BM(0.04), p=0.518) and hindgut fermenters (32 BM(0.00), p=1.00). The scaling exponent for ruminants only showed a tendency towards significance (29 BM(0.12), p=0.071). Ruminants on average had an MRT(particle) 1.61-fold longer than hindgut fermenters. Whereas an exponent of 0.25 is reasonable from theoretical considerations, much lower exponents were found in this and other studies. The energetic benefit of increasing MRT is by no means continuous, since the energy released from a given food unit via digestion decreases over time. The low and non-significant scaling factors for both digestion types suggest that in ungulates, MRT is less influenced by BM (maximal allometric exponent ≤0.1) than often reported.     

Hypsodonty and tooth facet development in relation to diet and habitat in herbivorous ungulates: implications for understanding tooth wear

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SD大鼠和Beagle犬大唾液腺的形态学观察

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PHYLOGENETICALLY INFORMED ANALYSIS OF THE ALLOMETRY OF MAMMALIAN BASAL METABOLIC RATE SUPPORTS NEITHER GEOMETRIC NOR QUARTER-POWER SCALING

The form of the relationship between the basal metabolic rate (BMR) and body mass (M) of mammals has been at issue for almost seven decades, with debate focusing on the value of the scaling exponent ( b , where BMR ∝ M^b ) and the relative merits of b = 0.67 (geometric scaling) and b = 0.75 (quarter-power scaling). However, most analyses are not phylogenetically informed (PI) and therefore fail to account for the shared evolutionary history of the species they consider. Here, we reanalyze the most rigorously selected and comprehensive mammalian BMR dataset presently available, and investigate the effects of data selection and phylogenetic method (phylogenetic generalized least squares and independent contrasts) on estimation of the scaling exponent relating mammalian BMR to M. Contrary to the results of a non-PI analysis of these data, which found an exponent of 0.67–0.69, we find that most of the PI scaling exponents are significantly different from both 0.67 and 0.75. Similarly, the scaling exponents differ between lineages, and these exponents are also often different from 0.67 or 0.75. Thus, we conclude that no single value of b adequately characterizes the allometric relationship between body mass and BMR.     

Environmental correlates of physiological variables in marsupials

We analyzed body temperature (T(b)), basal metabolic rate (BMR), wet thermal conductance (C(wet)), and evaporative water loss (EWL) of marsupials by conventional and phylogenetically corrected regression. Allometric effects were substantial for BMR, C(wet), and EWL but not T(b). There was a strong phylogenetic signal for mass and all physiological traits. A significant phylogenetic signal remained for BMR, C(wet), and EWL even after accounting for the highly significant phylogenetic signal of mass. T(b), BMR, C(wet), and EWL allometric residuals were correlated with some diet, distribution, and climatic variables before and after correction for phylogeny. T(b) residuals were higher for marsupials from arid environments (high T(a) and more variable rainfall). The fossorial marsupial mole had a lower-than-expected T(b) residual. The allometric slope for BMR was 0.72-0.75. Residuals were consistently related to distribution aridity and rainfall variability, with species from arid and variable rainfall habitats having a low BMR, presumably to conserve energy in a low-productivity environment. The nectarivorous honey possum had a higher-than-expected BMR. For C(wet), the allometric slope was 0.55-0.62; residuals were related to diet, with folivores having low and insectivores high C(wet) residuals. The allometric slope for EWL was 0.68-0.73. EWL residuals were consistently correlated with rainfall variability, presumably facilitating maintenance of water balance during dry periods.     

Quantitation of malaria sporozoites in the salivary glands of wild Afrotropical Anopheles

The number of malaria sporozoites in the salivary glands was determined microscopically for 1137 wild, naturally infected Anopheles from western Kenya. Infective Anopheles gambiae Giles sensu lato (n = 874) contained a geometric mean (GM) of 962 sporozoites and An.funestus Giles (n = 263) contained 812. No significant differences were detected in geometric mean numbers of sporozoites between species, collection techniques or sites. Of the infective An.gambiae, 1.7% (15/874) contained more than 41,830 sporozoites, the maximum observed for An.funestus. Microscopic techniques were found to be more sensitive than enzyme-linked immunosorbent assays (ELISA) for detecting low-grade sporozoite infections in salivary glands. Salivary gland sporozoites from 83.6% of the 1137 gland infections were identified by ELISA as either Plasmodium falciparum Welch (n = 910), P.ovale Stephens (n = 7), P.malariae Grassi & Feletti (n = 3) or mixed (n = 30). The 187 gland infections which could not be identified by ELISA contained significantly fewer sporozoites (GM = 242) than those which could be identified (GM = 1200).     

Mapping Relative Differences in Human Salivary Gland Secretions by Dried Saliva Spot Sampling and nanoLC–MS/MS

Dried saliva spot sampling is a minimally invasive technique for the spatial mapping of salivary protein distribution in the oral cavity. In conjunction with untargeted nano‐flow liquid chromatography tandem mass spectrometry (nanoLC–MS/MS) analysis, DSS is used to compare the proteomes secreted by unstimulated parotid and submandibular/sublingual salivary glands. Two hundred and twenty proteins show a statistically significant association with parotid gland secretion, while 30 proteins are at least tenfold more abundant in the submandibular/sublingual glands. Protein identifications and label‐free quantifications are highly reproducible across the paired glands on three consecutive days, enabling to establish the core proteome of glandular secretions categorized into eight salivary protein groups according to their biological functions. The data suggest that the relative contributions of the salivary glands fine‐tune the biological activity of human saliva via medium‐abundant proteins. A number of biomarker candidates for Sjögren's syndrome are observed among the gland‐specifically expressed proteins, which indicates that glandular origin is an important factor to consider in salivary biomarker discovery.     

Salivary glands in Cicadidae (Hemiptera: Cicadoidea): comparative morphology, ultrastructure, and their phylogenetic significance

The present investigation provides information on gross morphology and ultrastructure of salivary glands of species in Cicadidae in detail. The structure of the salivary glands of 11 representative species from 10 genera belonging to three subfamilies of Cicadidae was studied using light microscopy and transmission electron microscopy. In the examined species, the salivary glands are paired structures, and each of which is comprised of a principal gland (pg) and an accessory gland (ag). The pg is divided into anterior and posterior lobes, and both of which consist of numerous long digitate lobules. The lobules at the base of the long digitate lobules of posterior lobe are greatly short; here, we named as “short lobules.” All the lobules vary in size, disposition, length, and shape. The anterior lobe and posterior lobes are connected by an anterior–posterior duct (apd). Two efferent salivary ducts (esd), derived from corresponding posterior lobes, fuse to form a short common duct which enters into the saliva syringe. The ag is composed of a greatly tortuous and folded accessory salivary tube, a gular gland (gg) constituting of several acini, and an accessory salivary duct (asd). The asd joins the esd at the place where the latter emergences. Constituents and arrangement of the salivary glands, the number and shape of the long digitate lobules in the anterior and posterior lobes, and the visibility of the apd were promising characters for the taxonomic and phylogenetic analysis of Cicadoidea. The variations of secretory granules in size, shape, and electron density in lobule cells of pg of Platypleura kaempferi probably indicating different materials are synthesized. The absence of the infoldings of basal plasma membrane in the basal area of the cells and the presence of electron-lucent vesicles in the cytoplasm of the gg cells of P. kaempferi might suggest that the secretions of gg are more watery.     

Role of ovarian secretions in mammary gland development and function in ruminants

The mammary gland is a dynamic organ that undergoes cyclic developmental and regressive changes during the lifetime of a female mammal. Mammogenesis begins during embryonic life with the development of the first mammary gland rudiments and ductal system. After birth, during the pre-pubertal period, the ductal growth of the mammary parenchyma occurs through the fat pad. In most of the ruminant species allometric mammary parenchyma development begins with the onset of cyclic ovarian secretions activity. The two main hormones secreted during an ovarian cycle are estradiol and progesterone. These steroid hormones are derived from cholesterol and are synthesized by theca and granulosa cells in ovaries. During puberty, the mammary parenchyma develops in a compact, highly arborescent parenchymal mass surrounded by a dense connective matrix. Ductal elongation and lobulo-alveolar development are accomplished during growth and pregnancy to prepare for future milk production. At the end of lactation, the mammary gland undergoes involution, which corresponds to a regression of the secretory tissue, a reduction in the alveolar size and a loss of mammary epithelial cells (MECs). Ovarian steroids (estradiol and progesterone) appear to be key regulators of the different stages of mammogenesis and mammary function. Through this review, the role and the importance of ovarian steroids on mammary gland and on MECs is described.     

Analysis of parotid and mixed saliva in Roe deer (Capreolus capreolus L.)

In ruminants, different functions have been ascribed to the different salivary glands according to the feeding type. In this context, possible adaptations of salivary functions were investigated regarding the secretion of various proteins by different types of salivary glands. To yield uncontaminated parotid saliva in large quantities, a non-surgical method has been developed. Parotid gland secretions were collected via endoscopic placement of guide wires into each parotid duct, which were subsequently used for placement of collection catheters. Salivary flow was stimulated by intra-glandular administration of the parasympathomimetic compound pilocarpine-hydrochloride into the parotid gland. Mixed saliva (excluding parotid saliva) was collected into sterile tubes by normal outflow during the sampling of parotid saliva. The total flow volume, flow rate and the content of proteins as well as of several ions (Na⁺, K⁺, Ca²⁺, inorganic phosphate) of both types of saliva were measured in sheep, fallow deer and roe deer. Roe deer secreted the highest amount of total salivary proteins relative to body mass [mg/kg body mass] and the highest relative volume [ml/10 min/kg body mass], both in parotid and mixed saliva, of all ruminant species examined. Additionally, the protein profile and the tannin-binding properties of parotid and mixed saliva in roe deer were investigated. Parotid saliva bound almost twice as much tannin as mixed saliva, underlining the importance of yielding uncontaminated parotid saliva for tannin-binding studies. Accepted: 6 January 1998     

Diagnostic difficulties in the interpretation of fine needle aspirates of salivary gland lesions: the problem revisited

Diagnostic difficulties in the interpretation of he needle aspirates of salivary gland lesions: the problem revisited
Cases of salivary gland lesions ( n =325), mainly neoplastic but including a small number of non-neoplastic lesions, investigated by fine needle aspiration (FNA) and with histological correlation, are reviewed. The review identified a number of differential diagnostic problems which are discussed in some detail. One false-positive and eight false-negative diagnoses had been made resulting in a 99.5% specificity and a 85.5% sensitivity. If type-specific diagnoses are made only when all defined diagnostic criteria are present and if any uncertainty is clearly conveyed to the clinician, FNA is a safe and accurate tool in the investigation of salivary gland lesions.     

Human salivary gland branching morphogenesis: morphological localization of claudins and its parallel relation with developmental stages revealed by expression of cytoskeleton and secretion markers

Development of salivary glands is a highly complex and dynamic process termed branching morphogenesis, where branched structures differentiate into mature glands. Tight junctions (TJ) are thought to play critical roles in physiological functions of tubular organs, contributing to cell polarity and preventing lateral movement of membrane proteins. Evidence demonstrated that claudins are directly involved in TJ formation and function. Using immunohistochemistry and immunofluorescence we have mapped the distribution of claudins-1, 2, 3, 4, 5, 7 and 11 and compared it with the expression of differentiation markers in human salivary glands obtained from foetuses ranging from weeks 4 to 24 of gestation. Expression of all claudins, except claudin-2 was detected in the various phases of human salivary gland development, up to fully mature salivary gland. The expression of all claudins increased according to the progression of salivary gland maturation evidenced by the classical markers-cytokeratin 14, cytokeratin low molecular weight, smooth muscle actin and human secretory component. Tight junction proteins-claudins appear to be important in the final shape and physiological functions of human salivary glands and are parallel related with markers of salivary gland differentiation.     

Kidney mass and relative medullary thickness of rodents in relation to habitat, body size, and phylogeny

We tested the hypotheses that relative medullary thickness (RMT) and kidney mass are positively related to habitat aridity in rodents, after controlling for correlations with body mass. Body mass, mass-corrected kidney mass, mass-corrected RMT, mass-corrected maximum urine concentration, and habitat (scored on a semiquantitative scale of 1-4 to indicate increasing aridity) all showed statistically significant phylogenetic signal. Body mass varied significantly among habitats, with the main difference being that aquatic species are larger than those from other habitats. Mass-corrected RMT and urine concentration showed a significant positive correlation (N=38; conventional r=0.649, phylogenetically independent contrasts [IC] r=0.685), thus validating RMT as a comparative index of urine concentrating ability. RMT scaled with body mass to an exponent significantly less than 0 (N=141 species; conventional allometric slope=-0.145 [95% confidence interval (CI)=-0.172, -0.117], IC allometric slope=-0.132 [95% CI=-0.180, -0.083]). Kidney mass scaled to an exponent significantly less than unity (N=104 species; conventional slope=0.809 [95% CI=0.751, 0.868], IC slope=0.773 [95% CI=0.676, 0.871]). Both conventional and phylogenetic analysis indicated that RMT varied among habitats, with rodents from arid areas having the largest values of RMT. A phylogenetic analysis indicated that mass-corrected kidney mass was positively related to habitat aridity.     

Gastral exocrine products of a myrmicine ant strongly overlap pygidial gland products of Dolichoderinae

In most subfamilies of ants (Formicidae), a pygidial gland occurs in the worker’s dorsal gaster, and where tested, products of this gland function in alarm/defense and/or recruitment communication. These products are well characterized for members of the subfamily Dolichoderinae but remain unidentified for Myrmicinae. Both major and minor workers of one myrmicine, Pheidole biconstricta Mayr, are known to have greatly hypertrophied pygidial glands with alarm/repellent products. GC/MS analysis of methanol extracts of worker gasters revealed actinidine and six diastereomers of iridodials as major components, as well as lesser amounts of two lactones, iridomyrmecin and dihydronepetalactone. The iridoids also occur in the pygidial glands of some dolichoderines. Results are related to functional and phylogenetic considerations. Received 20 December 2004; revised 25 February 2005; accepted 4 March 2005. Work performed at Estación Biológica Cocha Cashu, Madre de Dios, Peru, and Virginia Military Institute, Lexington, VA.     

Observations on the production of purple pigments in the egg capsules,hypobranchial and reproductive glands from seven species of Muricidae (Gastropoda: Mollusca)

Summary

Tyrian purple is a well-known colourant that can be obtained from the hypobranchial glands of muricids. Here we investigate the presence of purple and related pigments in the hypobranchial glands, reproductive glands and egg capsules of three Rapaninae, three Ocenebrinae and one Muricinae species. Observations on the dissected specimens revealed the presence of purple pigmentation in the hypobranchial glands of all species. All of the Rapaninae and the Muricinae, but only some species of Ocenebrinae, appear to transfer the pigment precursors to their egg capsules. This provides evidence that the precursors of Tyrian purple are not produced for the sole purpose of protecting the egg masses as has been previously suggested. In all the subfamilies, the hypobranchial and reproductive (capsule and prostate) glands lie adjacent to one another. Colour changes in the reproductive glands, indicating the presence of dye precursors, were observed in two species of Rapaninae. In Dicathais orbita, colour changes could be seen in both the capsule glands of females and prostrate glands of males. The final colour was more red in the reproductive glands than the purple observed in the hypobranchial glands. Preliminary observations of detached hypobranchial gland sections in both D. orbita and Pterynotus triformis indicate a different suite of colour reactions occur when compared to sections that are intact and attached to the reproductive glands. This demonstrates that the reproductive glands can influence the chemical conversions of dye precursors synthesized by these species. Further studies on the secondary metabolism occurring within the hypobranchial glands and reproductive organs of Muricidae are ongoing, including histological sectioning and confirmation of the chemistry behind the colours observed and functional analysis of Tyrian purple precursors.