Structure and growth pattern of the bizarre hemispheric prominence on the rostrum of the fossil beaked whale Globicetus hiberus (Mammalia,Cetacea, Ziphiidae)

The rostrum of most ziphiids (beaked whales) displays bizarre swollen regions, accompanied with extreme hypermineralisation and an alteration of the collagenous mesh of the bone. The functional significance of this specialization remains obscure. With the voluminous and dense hemispheric excrescence protruding from the premaxillae, the recently described fossil ziphiid Globicetus hiberus is the most spectacular case. This study describes the histological structure and interprets the growth pattern of this unique feature. Histologically, the prominence in Globicetus is made up of an atypical fibro‐lamellar complex displaying an irregular laminar organization and extreme compactness (osteosclerosis). Its development is suggested to have resulted from a protraction of periosteal accretion over the premaxillae, long after the end of somatic growth. Complex shifts in the geometry of this tissue are likely to have occurred during its accretion and no indication of Haversian remodeling could be found. X‐ray diffraction and Raman spectroscopy indicate that the bone matrix in the premaxillary prominence of Globicetus closely resembles that of the rostrum of the extant beaked whale Mesoplodon densirostris: apatite crystals are of common size and strongly oriented, but the collagenous meshwork within bone matrix seems to be extremely sparse. These morphological and structural data are discussed in the light of functional interpretations proposed for the highly unusual and diverse ziphiid rostrum. J. Morphol. 277:1292–1308, 2016. © 2016 Wiley Periodicals, Inc.     

Ecological associations of autopodial osteology in Neotropical geckos

Coevolution of form and function inspires investigation of associations between morphological variation and the exploitation of specific ecological settings. Such relationships, based mostly on traits of external morphology, have been extensively described for vertebrates, and especially so for squamates. External features are, however, composed by both soft tissues and bones, and these likely play different biomechanical roles during locomotion, such as in the autopodia. Therefore, ecological trends identified on the basis of external morphological measurements may not be directly correlated with equivalent variation in osteology. Here, we investigate how refined parameters of autopodial osteology relate to ecology, by contrasting climbing and nonclimbing geckos. Our first step consisted of inferring how external and osteological morphometric traits coevolved in the group. Our results corroborate the hypothesis of coevolution between external and osteological elements in the autopodia of geckos, and provides evidence for associations between specific osteological traits and preferred locomotor habit. Specifically, nonclimbers exhibit longer ultimate and penultimate phalanges of Digit V in the manus and pes and also a longer fifth metatarsal in comparison with climbers, a pattern discussed here in the context of the differential demands made upon locomotion in specific ecological contexts. Our study highlights the relevance of osteological information for discussing the evolution of ecological associations of the tetrapod autopodium. J. Morphol. 278:290–299, 2017. © 2017 Wiley Periodicals, Inc.     

Dual role of osteoblastic proenkephalin derived peptides in skeletal tissues

Proenkephalin encodes a group of small peptides with opiate-like activity, the endogenous opioids, known to function as neurohormones, neuromodulators, and neurotransmitters. Recently, we have demonstrated that in addition to its abundance in fetal brain tissue, proenkephalin is highly expressed in nondifferentiated mesodermal cells of developing fetuses. We identified the skeletal tissues, bone, and cartilage as major sites of proenkephalin expression. To examine the possibility that proenkephalin is involved in bone development we have studied the expression of this gene in bone-derived cells, its modulation by bone active hormones, and the effects of enkephalin-derived peptides on osteoblastic phenotype. Our studies revealed that osteoblastic cells synthesize high levels of proenkephalin mRNA which are translated, and the derived peptides are secreted. Reciprocal interrelationships between osteoblast maturation and proenkephalin expression were established. These results together with our observations demonstrating inhibitory effects of proenkephalin-derived peptides on osteoblastic alkaline phosphatase activity, strongly support the notion that proenkephalin is involved in bone development. A different direction of research by other investigators has established the capability of the opioid system in the periphery to participate in the control of pain. On the basis of these two lines of observation, we would like to present the following hypothesis: The potential of embryonic skeletal tissue to synthesize proenkephalin-derived peptides is retained in the adult in small defined undifferentiated cell populations. This potential is realized in certain situations requiring rapid growth, such as remodeling or fracture repair. We suggest that in these processes, similarly to the situation in the embryo, the undifferentiated dividing cells produce the endogenous opioids. In the adult these peptides may have a dual function, namely participating in the control of tissue regeneration and in the control of pain. © 1994 Wiley-Liss, Inc.     

Structure of bone in the skulls of Neanderthal fossils

Close inspection of surface bone in skulls of Neanderthal man reveals weathering cracks extensive enough in one specimen, La Chapelle-aux-Saints, to allow preliminary analysis of major patterns of orientation and to make inferences about functional relationships of structures. The fine structure of the bone of the brow ridges is very different from the rest of the skull in the two adults examined, having a peculiar vermiculate surface pattern. Weathering cracks do not appear in this region. This indicates that Neanderthal brow ridges are not closely related to normal mechanical forces such as chewing exertion. It may, however, give further support to theories of Neanderthal brow ridges as protection for the eyes. The localized structure of bone often differs from region to region, and offers new possibilities for the analysis of both contemporary and fossil forms.     

Feedbacks between nutrient cycling and vegetation predict plant species coexistence and invasion

To investigate the role of species‐specific litter decomposability in determining plant community structure, we constructed a theoretical model of the codevelopmental dynamics of soil and vegetation. This model incorporates feedback between vegetation and soil. Vegetation changes the nutrient conditions of soil by affecting mineralization processes; soil, in turn, has an impact on plant community structure. The model shows that species‐level traits (decomposability, reproductive and competitive abilities) determine whether litter feedback effects are positive or negative. The feedback determines community‐level properties, such as species composition and community stability against invasion. The model predicts that positive feedback may generate multiple alternative steady states of the plant community, which differ in species richness or community composition. In such cases, the realized state is determined by initial abundance of co‐occurring species. Further, the model shows that the importance of species‐level traits depends on environmental conditions such as system fertility.     

A comparison of three noise reduction procedures applied to bird vocal signals

ABSTRACT.   Recordings of avian vocal signals in natural habitats include ambient noise. Often this background noise corrupts across all frequencies and is of substantial amplitude. Reducing this ambient noise to prepare vocal signals for playback stimuli or to remove habitat-specific noise signatures prior to analyzing a signal's acoustic characteristics can be useful. We conducted experimental evaluations of three noise reduction procedures to determine their effectiveness. We embedded two bird vocalizations ("clean" signals) in four kinds of natural noise, resulting in eight noise-signal combinations. We then applied three noise reduction procedures (Noise Profile, Band Pass, and Noise Estimate) to each of the embedded signals and compared the recovered signals to the original (clean) signals. Noise Profile filtering was effective in reducing noise and returning fairly high-quality signals from even severe levels of masking noise. The other two noise reduction procedures did not perform as well. For the two most corrupting maskers, however, Noise Profile filtering also altered the signal properties by reducing signal amplitude at those frequencies containing high levels of noise. Apart from this loss of amplitude, the quantitative features of the filtered signals were similar to those of the original model sounds. We conclude that Noise Profile filtering produces good results for cases where noise is approximately constant over the signal duration and the signal intensity exceeds noise intensity over the frequencies of interest.     

Activation of Integrin αVβ3 Regulates Cell Adhesion and Migration to Bone Sialoprotein

α_Vβ₃, a broadly distributed member of the integrin family of adhesion receptors, has been implicated in a variety of physiological and pathophysiological events, including control of bone density, angiogenesis, apoptosis, tumor growth, and metastasis. Recently, it has been shown that activation of α_Vβ₃, its transition from a low- to a high-affinity/avidity state, influences its recognition of certain ligands. Bone sialoprotein (BSP) is recognized as an important ligand for α_Vβ₃ in processes ranging from bone formation to the homing of metastatic tumor cells. Here, the influence of α_Vβ₃ activation on the adhesion and migration of relevant cells to BSP has been examined. Stimulation of lymphoblastoid, osteoblastoid, and human umbilical vein endothelial cells (HUVEC) with PMA or Mn²⁺ markedly enhanced α_Vβ₃-dependent adhesion to BSP. α_Vβ₃-mediated migration of HUVEC or osteoblastic cells to BSP was substantially enhanced by stimulation, demonstrating that α_Vβ₃ activation enhances both adhesive and migratory responses. However, adhesion and/or migration of certain tumor cell lines, including M21 melanoma and MDA MB435 and SKBR3 breast carcinoma cell lines, to BSP was constitutively high and was not augmented by α_Vβ₃-activating stimuli. Inhibitors of the intracellular signaling molecules, phosphatidylinositol 3-kinase with wortmannin, hsp90-dependent kinases with geldanamycin, and calpain with calpeptin, but not MAPKK with PD98059, reduced the high spontaneous adhesion and migration of the M21 cells to BSP, consistent with the constitutive activation of the receptor on these tumor cells. These results indicate that the activation state of α_Vβ₃ can regulate cell migration and adhesion to BSP and, by extension, to other ligands of this receptor. The constitutive activation of α_Vβ₃ on neoplastic cells may contribute to tumor growth and metastatic potential.     

The effect of canopy filtered light on the growth of white clover Trifolium repens

Summary Plants of white clover (Trifolium repens) were grown under canopies of clover leaves floating on shallow glass tanks of water and their growth was compared with that of plants under canopies of black polythene leaves. The experimental design allowed the growth of the clover plants in canopy filtered light to be compared with that in unfiltered light at different intensities of Photosynthetically Active Radiation (P.A.R.). The effect of canopy filtered light was to exaggerate the effects of reduced P.A.R. especially in promoting petiole extension and inhibiting stolon branching. Two clones of white clover differed in their responses to P.A.R. and to light quality and there were significant interactions between the effects of the intensity of P.A.R. and type of shade. It is argued that it may be important for both ecologists and plant breeders to recognise the role of radiation quality in regulating the dynamics of pasture.     

Why does the bud-galling sawfly,Euura mucronata,attack long shoots?

Summary The bud-galling sawfly, Euura mucronata, attacked longer shoot length classes on its host, Salix cinerea, more frequently than shorter shoots. Shoot length accounted for 76 to 93 percent of the variance in number of galls per 100 shoots in three habitats: forest, watermeadow, and lakeside. The reasons for this pattern were addressed with studies on shoot length in relation to: 1. Number of resources (buds) per shoot; 2. Success in establishment of larvae in galls; 3. Gall size and resources per gall; and 4. Survival of larvae after establishment as influenced by plant resistance and natural enemy attack. The most important factors proved to be success in establishment of larvae, with percent of variance accounted for ranging from 57 to 77 percent in three of four sites where relationships were significant, and survival after establishment of larvae, with variance accounted for ranging from 40 to 54 percent in the same three sites. The pattern of survival was dictated by plant resistance and not by natural enemies. These two additive factors resulted in a general relationship across all sites of increasing emergence of fully developed larvae per cohort as shoot length increased, accounting for 78 percent of the variance. These adaptive advantages to attacking longer shoots are sufficient to account for the pattern of increased probability of shoots being attacked as they increase in length.