How to contend with paraphyly in the taxonomy of the delphinine cetaceans?

Molecular phylogenetic analyses conducted over the past 15 yr have consistently had difficulties resolving relationships among the cetacean species in the subfamily Delphininae. In addition, paraphyly of the genera Tursiops and Stenella in these molecular phylogenies has been a recurrent problem since the first appearance of such a phylogeny in 1999, suggesting that these genera do not accurately reflect the evolutionary relationships of the species they contain. Morphological analyses have not resolved the issues. The genera in Delphininae originated in the 19th Century on questionable morphological grounds. The species were nearly all originally described in the genus Delphinus of Linnaeus. Recent molecular phylogenies based on various mitochondrial and nuclear DNA markers have suggested a wide range of possible relationships among these taxa, and several authors have suggested synonymizing all the taxa (Lagenodelphis, Stenella, Sousa, and Tursiops) under Delphinus. Until molecular and/or morphological analyses adequately sort out relationships in this very recently radiated group, one possible solution indeed would be to merge all the delphinine genera with Delphinus. Implications of such a move and alternatives are discussed.

Editor's Note: Papers from past Norris Award winners have primarily been a revised or reduced version of the actual presentation given as a plenary talk at the biennial conference. Dr. Perrin requested being allowed to take a topic from his presentation and expand on it to present a set of ideas in the form of an essay that could pass the rigors of the peer‐review process. As a result, this Norris Award paper has undergone peer‐review and has taken longer than usual for a Norris Award paper to appear in the journal following its presentation at the biennial conference. It also has co‐authors, with varying opinions on the issues discussed in the essay, to cover appropriately and more thoroughly those components of the paper that required additional expertise. I believe this approach has produced an excellent, thought‐provoking essay and is an approach that should be available to future Norris Award winners if they so choose to take it. Since this essay is meant to elicit dialogue, comments are welcome and will be considered for publication in Letters to the Editor.

     

Does the accumulation of trace metals in crustaceans affect their ecology—the amphipod example?

Crustaceans, like all aquatic invertebrates, take up and accumulate metals from a wide range of sources and the trace metal concentrations within their tissues and bodies show great variability. Trace metal uptake in crustaceans occurs from the water and food, either of which may be affected by the physico-chemical properties of the sediment. Accumulated metal concentrations in amphipods are contrasted with those of other crustaceans and examples are given to show how external and internal factors affect bioaccumulation. One of the major pathways for the uptake of trace metals is from solution directly through permeable surfaces including the gills. Changes in salinity and oxygen tension can modify the uptake characteristics from solution particularly in the case of interstitial water within sediments. Infaunal amphipods have direct contact with the sediment and the bioavailabilities of trace metals depend on the strength of the metal binding which is determined by a combination of properties including grain size, organic content, the presence of metals such as lead and iron as well as other ambient environmental conditions. Metal concentrations within amphipod bodies reflect the bioavailabilities of trace metals in their habitat. Body size is one of the major factors contributing to individual variability in trace metal concentrations within species. For some amphipod species, there are differences in trace metal accumulation with gender, breeding and developmental stage. In amphipods, accumulated body metal concentrations are the best biomarkers for environmental metal availabilities. Metal accumulation affects the ecology of crustaceans as a consequence of the energy costs associated with excreting and/or detoxifying the incoming metals. If the costs are significant, then this may result in reduced growth and reproduction. The effects of accumulated metals on communities have yet to be determined. Accumulated metals in crustacean prey species may be transferred along the food chain, but biomagnification in fish appears unlikely. One of the main ecological challenges is the need to link molecular biomarkers with ecologically relevant life history characteristics including growth, survival, reproduction and recruitment.     

Do distantly related parasites rely on the same proximate factors to alter the behaviour of their hosts?

Phylogenetically unrelated parasites often increase the chances of their transmission by inducing similar phenotypic changes in their hosts. However, it is not known whether these convergent strategies rely on the same biochemical precursors. In this paper, we explored such aspects by studying two gammarid species (Gammarus insensibilis and Gammarus pulex; Crustacea: Amphipoda: Gammaridae) serving as intermediate hosts in the life cycle of two distantly related parasites: the trematode, Microphallus papillorobustus and the acanthocephalan, Polymorphus minutus. Both these parasite species are known to manipulate the behaviour of their amphipod hosts, bringing them towards the water surface, where they are preferentially eaten by aquatic birds (definitive hosts). By studying and comparing the brains of infected G. insensibilis and G. pulex with proteomics tools, we have elucidated some of the proximate causes involved in the parasite-induced alterations of host behaviour for each system. Protein identifications suggest that altered physiological compartments in hosts can be similar (e.g. immunoneural connexions) or different (e.g. vision process), and hence specific to the host-parasite association considered. Moreover, proteins required to alter the same physiological compartment can be specific or conversely common in both systems, illustrating in the latter case a molecular convergence in the proximate mechanisms of manipulation.     

Does the precision of a biological clock depend upon its period? Effects of the duper and tau mutations in Syrian hamsters

Mutations which alter the feedback loops that generate circadian rhythms may provide insight into their insensitivity to perturbation robustness) and their consistency of period (precision). I examined relationships between endogenous period, activity and rest (τ(DD), α and ρ) in Syrian hamsters using two different mutations, duper and tau, both of which speed up the circadian clock. I generated 8 strains of hamsters that are homozygous or heterozygous for the tau, duper, and wild type alleles in all combinations. The endogenous period of activity onsets among these strains ranged from 17.94+0.04 to 24.13 ± 0.04 h. Contrary to predictions, the variability of period was unrelated to its absolute value: all strains showed similar variability of τ(DD) when activity onsets and acrophase were used as phase markers. The τ(DD) of activity offsets was more variable than onsets but also differed little between genotypes. Cycle variation and precision were not correlated with τ(DD) within any strain, and only weakly correlated when all strains are considered together. Only in animals homozygous for both mutations (super duper hamsters) were cycle variation and precision reduced. Rhythm amplitude differed between strains and was positively correlated with τ(DD) and precision. All genotypes showed negative correlations between α and ρ. This confirms the expectation that deviations in the duration of subjective day and night should offset one another in order to conserve circadian period, even though homeostatic maintenance of energy reserves predicts that longer intervals of activity or rest would be followed by longer durations of rest or activity. Females consistently showed greater variability of the period of activity onset and acrophase, and of α, but variability of the period of offset differed between sexes only in super duper hamsters. Despite the differences between genotypes in τ(DD), ρ was consistently more strongly correlated with the preceding than the succeeding α.     

Could Bacillus biofilms enhance the effectivity of biocontrol strategies in the phyllosphere?

Maize (Zea mays L.), a major crop in Argentina and a staple food around the world, is affected by the emergence and re-emergence of foliar diseases. Agrochemicals are the main control strategy nowadays; however, they can cause resistance in insects and microbial pathogens and have negative effects on the environment and human health. An emerging alternative is the use of living organisms, i.e. microbial biocontrol agents, to suppress plant pathogen populations. This is a risk-free approach when the organisms acting as biocontrol agents come from the same ecosystem as the foliar pathogens they are meant to antagonize. Some epiphytic microorganisms may form biofilm by becoming aggregated and attached to a surface, as is the case of spore-forming bacteria from the genus Bacillus. Their ability to sporulate and their tolerance to long storage periods make them a frequently used biocontrol agent. Moreover, the biofilm that they create protects them against different abiotic and biotic factors and helps them to acquire nutrients, which ensures their survival on the plants they protect. This review analyzes the interactions that the phyllosphere-inhabiting Bacillus genus establishes with its environment through biofilm, and how this lifestyle could serve to design effective biological control strategies.     

Does the examiner's experience matter in evaluation of the kinematics of the upper limb?

This study aimed to evaluate test and retest reliability according to examiner experience with the three-dimensional kinematics of the trunk, scapula, and arm segments during flexion and unilateral abduction of the arm. Ten men and 10 women (mean age, 25.1 [1.1] years) participated in this study. Each volunteer participated in six test sessions, four on the first day (two for each examiner) and two on the second day (one for each examiner). A 48-h interval was given between test days. The assessments were made by one examiner with movement analysis experience and a second examiner without experience. For each session (intra-day), the volunteers performed five repetitions of unilateral arm flexions and abductions using their dominant arms. After 1 h, the data were re-collected and all markers were replaced. Data from the trunk, scapula, and arm were analysed at 30°, 60°, 90°, and 120° of arm flexion and abduction using intraclass coefficient correlation, standard error of the measurement, and analysis of variance. The results did not differ between the experienced and inexperienced examiners except for trunk axial rotation at all studied angles and for arm rotation at 120° of abduction. The examiner previously trained in movement analysis marker placement demonstrated the same intra-tester reliability as the inexperienced tester when marker placement accuracy was the variable of interest.     

Reversible Membrane Pearling in Live Cells upon Destruction of the Actin?Cortex

Membrane pearling in live cells is observed when the plasma membrane is depleted of its support, the cortical actin network. Upon efficient depolymerization of actin, pearls of variable size are formed, which are connected by nanotubes of ∼40 nm diameter. We show that formation of the membrane tubes and their transition into chains of pearls do not require external tension, and that they neither depend on microtubule-based molecular motors nor pressure generated by myosin-II. Pearling thus differs from blebbing. The pearling state is stable as long as actin is prevented from polymerizing. When polymerization is restored, the pearls are retracted into the cell, indicating continuity of the membrane. Our data suggest that the alternation of pearls and strings is an energetically favored state of the unsupported plasma membrane, and that one of the functions of the actin cortex is to prevent the membrane from spontaneously assuming this configuration.     

Properties of Streptomyces sp. endo-β-xylanases in relation to their applicability in kraft pulp bleaching

A screening of a collection of Streptomyces sp. strains has shown that Streptomyces achromogenes 5028 (S1), Streptomyces longisporus ruber 4–167 (S2) and Streptomyces sp. 8812 (S3) degraded efficiently beechwood xylan. The -xylanase activities present in the culture filtrate of the strains were purified to electrophoretic homogeneity and found to be typical non-debranching endo--xylanases (1,4--D-xylan xylanohydrolases: E.C. 3.2.1.8) with respective molecular weights of 25,000 (S1), 45,000 (S2) and 22,000 (S3). The enzymes were characterized with respect to their temperature–pH relationship and kinetic profile. Immunological experiments suggested that the enzyme produced by S1 belonged to family 11 of glycanases and the S3 enzyme to family 10. The three xylanases adsorbed onto crystalline cellulose but were catalytically inert towards this material, indicating a possible application of these enzymes in biobleaching processes. With respect to its effect on and brightness values in a DEDED bleaching sequence, the xylanase produced by the S1 strain appeared as comparable to a Trichoderma longibrachiatum commercial enzyme preparation (Novozym 431). Streptomyces sp. xylanases may find applications in elemental-chlorine-free bleaching procedures.     

Does Melanin Turnover Occur in the Eyes of Adult Vertebrates?

This paper is a review of what is known about the turnover of melanin in iris, choroid, and retinal pigment epithelium (RPE) of the adult vertebrate eye. Differences in size and structure of choroideal and retinal pigment epithelial melanin granules are shown by electron micrographs. The classical stages of melanin synthesis, including the premelanosome, are shown in the RPE of adult hamsters that had been exposed to intense light. Degradation or synthesis of melanin also seem to occur in the melanocytes of the choroid in these animals. It is postulated that all three pigmented eye tissues (iris, RPE, and choroid) of adult vertebrates form melanin granules in vivo. However, nothing is known about the amount of this turnover.     

Does larder-hoarding affect the condition of chicks in urban kestrels?

Hoarding by urban kestrels and its subsequent exploitation significantly increases the frequency and regularity of feeding during the early stage of the nestling period. Twelve kestrels’ nests situated in various part of the city were chosen to test whether hoarding could affect the chicks’ condition. Four nests (with 22 nestlings) were provided with food — one dead mouse per chick per day (F group) and 8 (43 nestlings) were used as a control group (NF). Nestlings were weighed daily, and the length of their tarsus was also measured when the oldest chick in the nest was 11 days old. 50% of the NF nests experienced a decrease in the number of nestlings but no nestlings were lost in any of the F nests. However, no significant differences were found between the groups either in body mass or tarsus length. A possible reason was the behaviour of the adults which could be interpreted as the regulation of the frequency of prey delivery depending on its presence or absence in the nest.     

Does allelopathy involve in the association pattern of Trifolium resupinatum?

Indoor experiments demonstrated that allelopathic potential of rosette and flowering plants of qort is an important factor explaining the growth reduction of its associated species. Aqueous tissue extracts of flowering plants exhibited strong inhibitory effects on the germination percentage and radicle growth rate of the tested species as compared with those of vegetative plants. Under laboratory conditions, this inhibition was in agreement with toxicity assessments of soil samples collected from the rhizosphere of T. resupinatum L., where shoot and root dry mass of the tested species were significantly reduced. Detoxification of allelochemicals by presence of activated carbon can eliminate the inhibitory effects of the different extracts. This technique clarifies the occurrence of allelopathic interference by qort on seed germination and seedling growth, and hence suspects the allelopathic potential of qort in the growth reduction of associate species under field conditions along with competition. This revised version was published online in August 2006 with corrections to the Cover Date.     

Does the type of exercise affect tryptophan catabolism in horses?

Tryptophan (Trp) is an essential amino acid which metabolises via the kynurenine pathway to generate a number of bioactive substances referred to as kynurenines. Among those are 3-hydroxykynurenine (3-HKyn) and quinolinic acid, which are neurotoxic, as well as kynurenic acid (Kyna) and xanthurenic acid (XA), which, similarly to nicotinamide (NAm), show neuroprotective and anti-depressive effects. Routine exercise is known to modulate Trp metabolism in skeletal muscle and is thus believed to reduce the risk of depressive states in humans and laboratory animals. Analogously, it was hypothesised that exercise can influence Trp metabolism in horses as well. The aim of this study was to evaluate the influence of two different types of exercise on Trp metabolism in horses of the same breed. A total of 32 purebred Arabian horses were involved in the study. The 22 three-year-old racehorses were subjected to short-time intense exercise. Ten other horses were made to perform endurance competitions at a distance of 80 km. Blood samples were collected at rest and following the end of the exercise period. Plasma concentrations of Trp, kynurenine (Kyn), Kyna, 3-HKyn, XA and NAm were determined using Ultra-High Performance Liquid Chromatography-Electrospray Ionisation-Tandem Mass Spectrometry. Short-time intense exercise led to an increase in plasma concentrations of Kyn, Kyna and XA. The endurance effort induced an increase in Kyna and a decrease in Trp and NAm levels. Both types of exercise, short-time intensive exercise and endurance exercise induced an increase in Trp metabolites, especially Kyna, and did not induce an increase in Trp level. Thus, from a pathophysiological perspective of the kynurenine pathway’s influence on mental state, both types of exercise induced beneficial effects in horses.     

Does the order of second-line treatment in rheumatoid arthritis matter?

In a prospective study 88 patients, with rheumatoid arthritis who had stopped taking gold, penicillamine, or levamisole were randomly allocated to one of the alternative drugs and followed up for a minimum of one year. Concurrent studies of the effects of gold, penicillamine, and levamisole prescribed in 123 patients as the first second-line drug were used for comparison. No difference in toxicity or efficacy between primary and secondary use of gold or penicillamine was identified. Variation in the toxicity of levamisole could in part be accounted for by changes in the dose regimen over the four years of study. The length of the treatment-free interval between drugs did not influence subsequent development of toxicity. These results suggest that an adverse reaction to one of the three second-line drugs studied should not prejudice the selection of another.     

Does a biological clock reside in the eye of quail?

The site (intra- vs. extraocular) of the circadian clock driving an ocular melatonin rhythm in Japanese quail was investigated by alternately covering the left and right eyes of individual quail, otherwise held in constant light (LL), for 12-hr periods. This procedure exposed each eye to a light-dark (LD) 12:12 light cycle 180 degrees (12 hr) out of phase with the LD 12:12 light cycle experienced by the other eye. This protocol entrained the melatonin rhythm in the left eye of quail 180 degrees out of phase with the rhythm expressed in the right eye. These results are compatible with the hypothesis that an independent light-entrainable circadian pacemaker resides in each eye; they are incompatible with the hypothesis that a single (or functionally single) extraocular pacemaker drives the ocular melatonin rhythm in both eyes. However, the results are also compatible with a model in which two independent extraocular circadian pacemakers, each with an exclusive photic input from one eye, drive the ocular melatonin rhythm.     

Does a favourable change in the living conditions of young Kenyans affect their body (morphological) structure?

The aim of this study is to describe changes in the body structure of young Kenyans as a result of an upturn in the living conditions. The analyzed changes in their body build were caused by regular lifestyle and nutrition. The research material was male youth aged between 18 and 26. All those young men were students of a basic vocational school in Nairobi (Kenya). The first research was carried out in 1999 (n=121), the second one (n=302) exactly 12 months later and at the same institution. Changes in the body structure were studied on 31 individuals, who were examined twice. The examined parameters included: body height, body weight, chest circumference, waist circumference and thigh circumference. Information was also collected on the period a given student had stayed at that institution, his tribal membership, the number of children in his household and his number in the sequence of births in his family. Also the date of birth (at least the year) was of significance. All the examined men, whose body structure changes were analyzed, belonged to the Bantu language group. The studied individuals were at an age when growth had already finished. A more significant increase was observed in body weight, waist and thigh circumference. A regular schedule of activities and meals served in the dormitory resulted in body weight changes in 87% of those individuals, who were reexamined. As the basic reason for the observed changes one can regard the improvement in the level of nutrition, which was described by the examined individuals as "good".