How nutritionally imbalanced is phloem sap for aphids?

Aphids harbour intracellular symbionts (Buchnera) that provide their host with amino acids present in low amounts in their diet, phloem sap. To find out the extent to which aphids depend on their symbionts for synthesis of individual essential amino acids, we have evaluated how well phloem sap amino acid composition matches the aphids' needs. Amino acid compositions of the ingested phloem sap were compared to amino acids in aphid body proteins and also to available information about optimal diet composition for other plant feeding insects. Phloem sap data from severed stylets of two aphid species, Rhopalosiphum padi (L.) (Homoptera: Aphididae) feeding on wheat, and Uroleucon sonchi (L.) (Homoptera: Aphididae) feeding on Sonchus oleraceus (L.), together with published information on phloem sap compositions from other plant species were used.Phloem sap has in general only around 20% essential amino acids, with a range from 15–48%. Aphid body proteins and optimal diets for two other plant feeding insects have around 50%. The phloem sap of early flowering S. oleraceus ingested by U. sonchi contained 48%, which seems to be exceptional. Aphids feeding on different plants appear to be very differently dependent on their symbionts for their overall essential amino acid synthesis, due to the large variation in proportion of essential amino acids in phloem sap from different plants.The profile of the essential amino acids in phloem sap from different plant species corresponds rather well to profiles of both aphid body proteins and optimal diets determined for plant feeding insects. However, methionine and leucine in phloem sap are in general low in these comparisons, suggesting a higher dependence on the symbiont for synthesis of these amino acids. Concentrations of several essential amino acids in phloem from different plant species seem to vary together, suggesting that levels of symbiont provisioning of different amino acids are adjusted in parallel.     

Who is publishing in Theriogenology and on what subjects?

An analysis of 503 articles published in the journal Theriogenology in 1984, 1987 and 1990 was conducted to identify research trends and researchers publishing in the journal. A 30.5% increase in the number of papers published was found for 1990. During the 3yr period studied, the United States and Canada accounted for 63.1% of the total number of articles published, followed by European countries with 14.3%, and by Asia with 12.0%. At least 1 paper was published from 41 countries. The United States, at the top of the list, increased its share from 16% in 1984 to 21% in 1990. The number of papers from Japan increased significantly while the percentage of participation from Europe declined. The female animal was the sole subject of 63.2% of the articles, and cattle were the most researched species, appearing in 44.3% of the studies. Although the estrous cycle was the most studied reproductive event in all 3 yr, there was also a trend for the popularity of this topic to decrease in favor of the subject fertilization. The number of authors per paper increased significantly over the years analyzed, as did the number of studies carried out in international cooperation. Institutes of higher education were represented in almost 70% of the papers, followed by research institutes (12.8%). The present analysis confirms the central role that the journal Theriogenology plays in the world-wide communication of research results in animal reproduction.     

Who is coordinating collective movements in black and gold howler monkeys?

Decisions about when and where to travel are likely to have a strong influence on the feeding, ecology, and foraging strategies of individual primates living in a cohesive social group. Specifically, given differences in age, sex, reproductive status, or social dominance, particular group members may benefit from remaining at their present location while others may benefit from traveling to another area of their range to feed or rest. In this study, we present data on movement coordination in two groups of wild black and gold howler monkeys inhabiting Isla Brasilera (27º 20′S and 58º 40′W) in northern Argentina. We examine how factors such as sex, age, reproductive status, and dominance affect patterns of group movement coordination at feeding or resting sites, and in the context of intergroup encounters. Two groups were followed five days a month from sunrise to sunset during June to November 2004. Using focal and scan sampling techniques, we recorded 262 group displacements, the identity of the individual initiating and leading displacement, and the identity of the first individual to arrive at feeding, resting, or intergroup encounter sites. We found that overall age was the only factor that influenced group coordination: adults led more often (94.5 %) than immature individuals (5.5 %) in both groups. We did not find differences among adults. However, we found that males lead more often than females at intergroup encounters, consistent with the male-mate defense hypothesis. The distributed leadership pattern among adults observed in this study may suggest that adult individuals make equally shared consensus decisions. This pattern should be further examined using this individual-level approach in other populations of black and gold howlers, other species of howlers, and in other atelines in which within-group social tolerance is the rule rather than the exception.     

Reactive oxygen intermediates in plant-microbe interactions: Who is who in powdery mildew resistance?

Reactive oxygen intermediates (ROIs) such as hydrogen peroxide (H(2)O(2)) and the superoxide anion radical (O*(2)(-)) accumulate in many plants during attack by microbial pathogens. Despite a huge number of studies, the complete picture of the role of ROIs in the host-pathogen interaction is not yet fully understood. This situation is reflected by the controversially discussed question as to whether ROIs are key factors in the establishment and maintenance of either host cell inaccessibility or accessibility for fungal pathogens. On the one hand, ROIs have been implicated in signal transduction as well as in the execution of defence reactions such as cell wall strengthening and a rapid host cell death (hypersensitive reaction). On the other hand, ROIs accumulate in compatible interactions, and there are reports suggesting a function of ROIs in restricting the spread of leaf lesions and thus in suppressing cell death. Moreover, in situ analyses have demonstrated that different ROIs may trigger opposite effects in plants depending on their spatiotemporal distribution and subcellular concentrations. This demonstrates the need to determine the particular role of individual ROIs in distinct stages of pathogen development. The well-studied interaction of cereals with fungi from the genus Blumeria is an excellent model system in which signal transduction and defence reactions can be further elucidated in planta. This review article gives a synopsis of the role of ROI accumulation, with particular emphasis on the pathosystem Hordeum vulgare L.- Blumeria graminis.     

Who is where in the Plastisphere,and why does it matter?

To fully understand how plastic is affecting the ocean, we need to understand how marine life interacts directly with it. Besides their ecological relevance, microbes can affect the distribution, degradation and transfer of plastics to the rest of the marine food web. From amplicon sequencing and scanning electron microscopy, we know that a diverse array of microorganisms rapidly associate with plastic marine debris in the form of biofouling and biofilms, also known as the “Plastisphere.” However, observation of multiple microbial interactions in situ, at small spatial scales in the Plastisphere, has been a challenge. In this issue of Molecular Ecology Resources, Schlundt et al. apply the combination labelling and spectral imaging – fluorescence in situ hybridization to study microbial communities on plastic marine debris. The images demonstrate the colocalization of abundant bacterial groups on plastic marine debris at a relatively high taxonomic and spatial resolution while also visualizing biofouling of eukaryotes, such as diatoms and bryozoans. This modern imaging technology provides new possibilities to address questions regarding the ecology of marine microbes on plastic marine debris and describe more specific impacts of plastic pollution in the marine food webs.     

Who is Calling? Intraspecific Call Variation in the Aromobatid Frog Allobates femoralis

Many territorial species respond less aggressively to familiar neighbours than to unfamiliar floating strangers based on individual differences in acoustic signals. This form of social recognition, termed neighbour–stranger discrimination (NSD) or dear-enemy phenomenon has been reported so far from three anuran species. To investigate the potential of auditory signal features to convey information on sender's identity, we determined patterns of within-male and between-male variability in the advertisement call of the aromobatid frog Allobates femoralis . We examined 285 calls from 19 males to assess those call properties showing sufficient and reliable inter-individual differences to function as possible recognition cues. Beside calls per call bout and call rate, all other examined call properties were more variable among males than within males. Generally, temporal call features showed higher between- and within-male variability ratios than spectral properties and contributed mostly to distinguish individual males in the discriminant-function analysis. Mean classification success of 64.9% correctly assigned calls to individual males is mainly attributable to three temporal call properties (duration of note 1 and 4, note repetition rate). Altogether, our results suggest that there is sufficient variation in the advertisement call to discriminate statistically among individual males. However, assessed call differences between A. femoralis males were rather small, suggesting that potential NSD might be based either on a combination of call features or even on the whole pattern of individual call variation instead on single call properties. Habituation–discrimination experiments in the field using modified playback signals to test for differential behavioural responses are required to confirm this hypothesis.     

Who is Who? Non-invasive Methods to Individually Sex and Mark Altricial Chicks

Many experiments require early determination of offspring''s sex as well as early marking of newborns for individual recognition. According to animal welfare guidelines, non-invasive techniques should be preferred whenever applicable. In our group, we work on different species of song birds in the lab and in the field, and we successfully apply non-invasive methods to sex and individually mark chicks. This paper presents a comprehensive non-invasive tool-box. Sexing birds prior to the expression of secondary sexual traits requires the collection of DNA-bearing material for PCR. We established a quick and easy method to sex birds of any age (post hatching) by extracting DNA from buccal swabs. Results can be obtained within 3 hours. For individual marking chick''s down feathers are trimmed in specific patterns allowing fast identification within the hatching order. This set of methods is easily applicable in a standard equipped lab and especially suitable for working in the field as no special equipment is required for sampling and storage. Handling of chicks is minimized and marking and sexing techniques are non-invasive thereby supporting the RRR-principle of animal welfare guidelines.     

Why is the subendocardium more vulnerable to ischemia? A new paradigm

Myocardial ischemia is transmurally heterogeneous where the subendocardium is at higher risk. Stenosis induces reduced perfusion pressure, blood flow redistribution away from the subendocardium, and consequent subendocardial vulnerability. We propose that the flow redistribution stems from the higher compliance of the subendocardial vasculature. This new paradigm was tested using network flow simulation based on measured coronary anatomy, vessel flow and mechanics, and myocardium-vessel interactions. Flow redistribution was quantified by the relative change in the subendocardial-to-subepicardial perfusion ratio under a 60-mmHg perfusion pressure reduction. Myocardial contraction was found to induce the following: 1) more compressive loading and subsequent lower transvascular pressure in deeper vessels, 2) consequent higher compliance of the subendocardial vasculature, and 3) substantial flow redistribution, i.e., a 20% drop in the subendocardial-to-subepicardial flow ratio under the prescribed reduction in perfusion pressure. This flow redistribution was found to occur primarily because the vessel compliance is nonlinear (pressure dependent). The observed thinner subendocardial vessel walls were predicted to induce a higher compliance of the subendocardial vasculature and greater flow redistribution. Subendocardial perfusion was predicted to improve with a reduction of either heart rate or left ventricular pressure under low perfusion pressure. In conclusion, subendocardial vulnerability to a acute reduction in perfusion pressure stems primarily from differences in vascular compliance induced by transmural differences in both extravascular loading and vessel wall thickness. Subendocardial ischemia can be improved by a reduction of heart rate and left ventricular pressure.     

Who puts the tubercle in tuberculosis?

Tuberculosis (TB), an illness that mainly affects the respiratory system, is one of the world's most pernicious diseases. TB currently infects one-third of the world's population and kills approximately 1.7 million people each year. Most infected individuals fail to progress to full-blown disease because the TB bacilli are 'walled off' by the immune system inside a tissue nodule known as a granuloma. The granuloma's primary function is one of containment and it prevents the dissemination of the mycobacteria. But what is the role of the TB bacillus in the progression of the granuloma? This Review explores how Mycobacterium tuberculosis influences granuloma formation and maintenance, and ensures the spread of the disease.