Saliva of the graminivorous Theropithecus gelada lacks proline‐rich proteins and tannin‐binding capacity

Gelada baboons are the sole survivors of the genus Theropithecus and the only known graminivorous primates. They developed special adaptations to their diet such as high‐crowned teeth for processing hard and abrasive feed. The fine‐tuning of salivary protein composition might be another key mechanism that is used by species for adapting to the environment and competing with rivals for exploiting new ecological niches. In order to test whether gelada (graminivorous) and hamadryas baboons (omnivorous) differ in their salivary protein composition, we compared whole saliva samples of captive Theropithecus gelada and Papio hamadryas using gel electrophoresis and tannin‐binding assay. We hypothesized that the amount of proline‐rich salivary proteins with tannin‐binding capacity is higher in baboons consuming a feed with high dicot/monocot rations. Dicots produce tannins as a chemical defense system, discouraging animals from eating them. In contrast to dicots, monocots do not synthesize tannins. The presence of tannin‐binding proteins in saliva should effectively inactivate the dicot tannin‐based defense mechanism and increase the dietary breadth and/or the capability to switch between monocots and dicot leaves. The lack of such tannin‐binding proteins in saliva would indicate a narrow dietary spectrum more restricted to monocots. We found T. gelada to completely lack proline‐rich proteins (PRPs) and tannin‐binding capacity similar to a great variety of other grazing mammals. In contrast, P. hamadryas does possess PRPs with tannin‐binding activity. The findings support a growing body of evidence suggesting a high‐level specialization of T. gelada to grass diets. However, it remains unclear, whether loss of salivary tannin‐binding capacity drove the gelada into its narrow feeding niche, or whether this loss is the result of a long process of increased specialization. Thus, from an ecological point of view, T. gelada appears to be more vulnerable to environmental changes than other baboon species owing to its narrow dietary traits. Am. J. Primatol. 71:663–669, 2009. © 2009 Wiley‐Liss, Inc.     

Structural Evidence of Substrate Specificity in Mammalian Peroxidases: STRUCTURE OF THE THIOCYANATE COMPLEX WITH LACTOPEROXIDASE AND ITS INTERACTIONS AT 2.4 ? RESOLUTION*S?

The crystal structure of the complex of lactoperoxidase (LPO) with its physiological substrate thiocyanate (SCN^–) has been determined at 2.4Å resolution. It revealed that the SCN^– ion is bound to LPO in the distal heme cavity. The observed orientation of the SCN^– ion shows that the sulfur atom is closer to the heme iron than the nitrogen atom. The nitrogen atom of SCN^– forms a hydrogen bond with a water (Wat) molecule at position 6′. This water molecule is stabilized by two hydrogen bonds with Gln⁴²³ N^ε2 and Phe⁴²² oxygen. In contrast, the placement of the SCN^– ion in the structure of myeloperoxidase (MPO) occurs with an opposite orientation, in which the nitrogen atom is closer to the heme iron than the sulfur atom. The site corresponding to the positions of Gln⁴²³, Phe⁴²² oxygen, and Wat⁶′ in LPO is occupied primarily by the side chain of Phe⁴⁰⁷ in MPO due to an entirely different conformation of the loop corresponding to the segment Arg⁴¹⁸–Phe⁴³¹ of LPO. This arrangement in MPO does not favor a similar orientation of the SCN^– ion. The orientation of the catalytic product OSCN^– as reported in the structure of LPO·OSCN^– is similar to the orientation of SCN^– in the structure of LPO·SCN^–. Similarly, in the structure of LPO·SCN^–·CN^–, in which CN^– binds at Wat¹, the position and orientation of the SCN^– ion are also identical to that observed in the structure of LPO·SCN.Lactoperoxidase (LPO⁴; EC 1.11.1.7) is a Fe³⁺ heme enzyme that belongs to the mammalian peroxidase family (1). The family of mammalian peroxidases comprises lactoperoxidase (2), eosinophil peroxidase (3), thyroid peroxidase (4), and myeloperoxidase (MPO) (5). LPO, eosinophil peroxidase, and MPO are responsible for antimicrobial function and innate immune responses (6–8), whereas thyroid peroxidase plays a key role in thyroid hormone biosynthesis (9). These peroxidases are different from plant and fungal peroxidases because unlike plant and fungal enzymes, the prosthetic heme group in mammalian peroxidases is covalently linked to the protein (10). There are also several striking structural and functional differences among the mammalian peroxidases (11). The heme group in MPO is attached to the protein via three covalent linkages (12), whereas LPO (12, 13), eosinophil peroxidase (12), and thyroid peroxidase (12) contain only two ester linkages. These covalent and various non-covalent linkages contribute differentially to the high stability of the heme core as well as for the peculiar values of their redox potentials (2, 14). Furthermore, MPO consists of two disulfide-linked protein chains, whereas LPO, eosinophil peroxidase, and thyroid peroxidase are single chain proteins, although their chain lengths differ greatly. In addition, their sequences contain several critical amino acid differences that may also contribute to the variations in the stereochemical environments of the substrate-binding sites. As a consequence of these differences, the mammalian enzymes oxidize various inorganic ions such as SCN^–, Br^–, Cl^–, and I^– with differing specificities and potencies. Biochemical studies have shown that LPO catalyzes preferentially the conversion of SCN^– to OSCN^– (15, 16), whereas MPO uses halides (17, 18) with a preference for chloride ion as the substrate. The preferences of eosinophil peroxidase and thyroid peroxidase are bromide and iodide, respectively. However, the stereochemical basis of the reported preferences for the substrates by mammalian heme peroxidases is still unclear. So far, the structures of only two mammalian enzymes, MPO and LPO, have been determined (12, 13). It is of considerable importance to identify the structural parameters that are responsible for the subtle specificities. In the present work, we have attempted to address this question through the new crystal structures of LPO complexes with SCN^– ions using goat, bovine, and buffalo lactoperoxidases. Because the overall structures of complexes of SCN^– with LPO from all three species were found to be identical, the structure of the complex of buffalo LPO with SCN^– and the ternary complex with SCN^– and CN^– will be discussed here, and buffalo LPO will be termed hereafter as LPO. To highlight the factors pertaining to binding specificity of SCN^–, a comparison of the structures of LPO·SCN^– and MPO·SCN^– has also been made, revealing many valuable differences pertaining to the observed orientations of the common substrate, SCN^– ion, when bound at the substrate-binding site in the distal heme cavity of the two structures. The structures of LPO·SCN^– and MPO·SCN^– clearly show that the bound SCN^– ions are present in the distal heme cavity of two enzymes with opposite orientations. In the structure of LPO·SCN^–, the sulfur atom is closer to the heme iron than the nitrogen atom, whereas in that of MPO·SCN^–, the nitrogen atom is closer to the heme iron than the sulfur atom. As a result of this, the interactions of the SCN^– ion in the distal site of two proteins differ drastically. Gln⁴²³, a conserved water (Wat) molecule at position 6′, and a well aligned carbonyl oxygen of Phe⁴²² in the proximity of the substrate-binding site in LPO against a protruding Phe⁴⁰⁷ in MPO seem to play the key roles in inducing the observed orientations of SCN^– ions in LPO and MPO. The structure of LPO·SCN^– has also been compared with the structure of its ternary complex with SCN^– and CN^– ions.     

First‐year seedlings and climate change: species‐specific responses of 15 North American tree species

Species will respond individually to climate change and this poses a challenge for modeling climate–vegetation dynamics using broader taxonomic or biogeographical classifications. Additionally, responses to climate and environmental conditions may shift with ontogeny, further complicating efforts to understand the likely rates and directions of vegetation change. We measured emergence, leaf‐out rate, growth, and survival of first‐year seedlings in response to warming, precipitation regime shifts, and seedbed condition (leaf litter presence/absence). We grouped species into three levels of organization (species‐specific, biome‐level and broad taxonomic group) and hypothesized that most metrics of seedling performance would be best described by species‐specific models, as even similar species may respond in vastly different ways to global change. Results showed that the species‐specific model was the best fit for emergence and development rates, whereas growth and survival could be captured through broader groupings, with the broadleaf temperate group exhibiting the greatest growth and conifers the shortest survival times. The sign and magnitude of response to climate and seedbed condition varied with treatment combinations and metric of performance. For example, seedlings grew more in response to warming, but conditions too dry or too wet limited this positive response. Also, warmer temperatures generally increased emergence, development, and growth, but decreased survival, whereas leaf litter presence decreased emergence and slowed development, but increased survival. The results presented here are for first‐year seedlings and in many cases the responses are different from other studies using older plants. Future research and climate vegetation modeling needs to assess performance at multiple development stages and determine where key bottleneck phases for population growth occur for individual species.     

Extracellular signal-regulated kinase 1/2 plays a pro-life role in experimental brain stem death via MAPK signal-interacting kinase at rostral ventrolateral medulla

Background  

As the origin of a life-and-death signal detected from systemic arterial pressure, which sequentially increases (pro-life) and decreases (pro-death) to reflect progressive dysfunction of central cardiovascular regulation during the advancement towards brain stem death in critically ill patients, the rostral ventrolateral medulla (RVLM) is a suitable neural substrate for mechanistic delineation of this fatal phenomenon. The present study assessed the hypothesis that extracellular signal-regulated kinase 1/2 (ERK1/2), a member of the mitogen-activated protein kinases (MAPKs) that is important for cell survival and is activated specifically by MAPK kinase 1/2 (MEK1/2), plays a pro-life role in RVLM during brain stem death. We further delineated the participation of MAPK signal-interacting kinase (MNK), a novel substrate of ERK in this process.     

Volume-based pollen size analysis: an advanced method to assess somatic and gametophytic ploidy in flowering plants

Pollen size is often used as a biological parameter to estimate the ploidy and viability of mature pollen grains. In general, pollen size quantification is performed one- or two-dimensionally using image-based diameter measurements. As these approaches are elaborate and time consuming, alternative approaches that enable a quick, reliable analysis of pollen size are highly relevant for plant research. In this study, we present the volume-based particle size analysis technique as an alternative method to characterize mature pollen. Based on a comparative assay using different plant species (including tomato, oilseed rape, kiwifruit, clover, among others), we found that volume-based pollen size measurements are not biased by the pollen shape or position and substantially reduce non-biological variation, allowing a more accurate determination of the actual pollen size. As such, volume-based particle size techniques have a strong discriminative power in detecting pollen size differences caused by alterations in the gametophytic ploidy level and therefore allow for a quick and reliable estimation of the somatic ploidy level. Based on observations in Arabidopsis thaliana gametophytic mutants and differentially reproducing Boechera polyantha lines, we additionally found that volume-based pollen size analysis provides quantitative and qualitative data about alterations in male sporogenesis, including aneuploid and diploid gamete formation. Volume-based pollen size analysis therefore not only provides a quick and easy methodology to determine the somatic ploidy level of flowering plants, but can also be used to determine the mode of reproduction and to quantify the level of diplogamete formation.     

Response of female Ceratitis capitata (Diptera: Tephritidae) to a spinosad bait and polymer matrix mixture with extended residual effect in Hawaii

The effectiveness of foliar applications of protein baits against pestiferous fruit flies (Tephritidae) can be adversely affected by a rapid loss of attractive volatile compounds and by rainfall due to the high water solubility of the baits. In a large coffee, Coffea arabica L., plantation in Hawaii with high and low populations of Mediterranean fruit fly, Ceratitis capitata (Wiedemann) (Diptera: Tephritidae), the relative attractiveness of GF-120 NF Naturalyte Fruit Fly Bait as either a 40% (vol:vol) spray solution (= GF-120 NF) or as a formulated proprietary amorphous polymer matrix (= GF-120 APM) was compared. The GF-120 APM formulations contained either, 25, 50, or 75% of GF-120 NF (wt:wt). All baits were tested in association with visually attractive yellow bait stations as a way of standardizing the evaluations. With both high and low C. capitata populations, significantly more females were attracted to the fresh sprayed GF-120 NF than to any of the three fresh GF-120 APM formulations. The attractiveness of GF-120 sprayed decreased significantly after 1 wk, whereas 1-wk-old GF-120 APM formulations were as attractive as similar fresh formulations. GF-120 APM 75% aged for 3 wk outperformed similarly-aged sprayed GF-120 NF with comparatively high C. capitata populations. With low populations, both GF-120 APM 75% and GF-120 APM 50% aged for 2 wk outperformed the similarly aged sprayed GF-120 NF. Combined findings indicate that APM mixed with either 50 or 75% GF-120 applied to bait stations can be attractive to female C. capitata for up to 3 wk longer than the standard sprayed GF-120 NF.     

Recent developments in the molecular genetics and biology of self-incompatibility

A summary of recent work on molecular aspects of self-incompatibility in Nicotiana alata is presented. The amino acid sequences of style proteins corresponding to different S-alleles of N. alata have a high level of homology in some regions and are variable in other regions. The regions of homology include N-terminal sequences as well as most of the glycosylation sites and cysteine residues. The glycosyl substituents may consist of a number of glycoforms. The isolated style S-glycoproteins inhibit in vitro growth of pollen tubes. The S-glycoproteins tested inhibited the growth of pollen of several S-genotypes, and there was some specificity in the interaction. Heat treatment of the isolated S-glycoproteins dramatically increased their activity as inhibitors of pollen tube growth, although the specificity in the interaction was lost. The nature of the S-allele products in pollen is not yet established.     

Indication of higher salivary α‐amylase expression in hamadryas baboons and geladas compared to chimpanzees and humans

Background Little is known about salivary α‐amylase expression in primates. Methods We compared saliva of gelada and hamadryas baboons, chimpanzees and humans using SDS‐PAGE and immunoblotting. Results and conclusions Amylase expression was increased in hamadryas baboons (P = 0.0376) compared to humans and might indicate dietary starch use in Cercopithecines.     

Saliva proteomics as an emerging, non-invasive tool to study livestock physiology, nutrition and diseases

Saliva is an extraordinary fluid in terms of research and diagnostic possibilities. Its composition in electrolytes, hormones and especially its proteome contains information about feeding status, nutritional requirements and adaptations to diet and environment, and also about health status of animals. It is easy to collect on a non-invasive and routine basis without any need for special training. Therefore, the analysis of salivary proteomes is going to emerge into a field of high interest with the future goal to maintain and improve livestock productivity and welfare. Moreover, the comprehensive analysis and identification of salivary proteins and peptides in whole and glandular saliva is a necessary pre-requisite to identify animal disease biomarkers and a powerful tool to better understand animal physiology. This review focuses on the different approaches used to study the salivary proteomes of farm animals, in respect to the physiology of nutrition and food perception in relation to food choices. The potential of animal saliva as a source of disease biomarkers will also be pointed out. Special emphasis is laid on the 'ruminating triad' - cattle, goat and sheep - as well as swine as major species of animal production in Western and Southern Europe.