Head width–body mass equation: facilitating worker termite biomass estimates

1. Termites are one of the most important invertebrate ecosystem engineers in tropical regions, which may be quantified using termite biomass data. However, biomass data are particularly difficult to collect as they rely on termites being weighed in the field, which may neither be possible nor convenient. Local scale linear regression models, based on termite head widths (mm) and body masses (mg), have been used in the past to estimate termite biomass using head width and abundance data. However, these models represent very limited numbers of termite taxa from single sites. In the present study, I provide one of the most representative linear regression models available based on 90 samples from three different countries (Peru, Kenya, and Malaysia). 2. Although the linear regression model under‐ or overestimated body weights of taxa with characteristic features (e.g. large heads of Odontotermes workers or elongated abdomens of Kalotermitidae) it provides a robust method for estimating termite biomass at the community level. Additionally, while there are limitations related to the general model, which may be solved by focusing on taxa specific data and the use of higher accuracy equipment, it is the first model to facilitate termite biomass estimates using the head with and abundance data only. 3. This study encourages the use of termite biomass data to gain a better understanding of termites in ecosystem processes and calls for comparative data to be gathered for the purpose of creating models that may be representative of the variability among termite taxa.     

Body size but not colony size increases with altitude in the holarctic ant,Leptothorax acervorum

1. Bergmann's rule states that organisms inhabiting colder environments show an increase in body size or mass in comparison to their conspecifics living in warmer climates. Although originally proposed for homoeothermic vertebrates, this rule was later extended to ectotherms. In social insects, only a few studies have tested this rule and the results were ambiguous. Here, ‘body size’ can be considered at two different levels (the size of the individual workers or the size of the colony). 2. In this study, data from 53 nests collected along altitudinal gradients in the Alps were used to test the hypotheses that the worker body size and colony size of the ant Leptothorax acervorum increase with increasing altitude and therefore follow Bergmann's rule. 3. The results show that the body size of workers but not the colony size increases with altitude. Whether this pattern is driven by starvation resistance or other mechanisms remains to be investigated.     

From the Schnauzenorgan to the back: Morphological comparison of mormyromast electroreceptor organs at different skin regions of Gnathonemus petersii

The nocturnally active weakly electric fish Gnathonemus petersii is known to employ active electrolocation for the detection of objects and for orientation in its environment. The fish emits pulse‐type electric signals with an electric organ and perceives these signals with more than 3,000 epidermal electroreceptor organs, the mormyromasts, which are distributed over the animal's skin surface. In this study, we measured the metric dimensions of the mormyromasts from different body regions to find structural and functional specialization of the various body parts. We focused on the two foveal regions of G. petersii, which are located at the elongated and movable chin (the Schnauzenorgan; SO) and at the nasal region (NR), the skin region between the mouth and the nares. These two foveal regions were compared to the dorsal part (back) of the fish, which contains typical nonfoveal mormyromasts. While the gross anatomy of the mormyromasts from all skin regions is similar, the metric dimensions of the main substructures differed. The mormyromasts at the SO are the smallest and contain the smallest receptor cells. In addition, the number of receptor cells per organ is lowest at the SO. In contrast, at the back the biggest receptor organs with the highest amount of receptor cells per organ occur. The mormyromasts at the NR are in several respects intermediate between those from the back and the SO. However, mormyromasts at the NR are longer than those at all other skin regions, the canal leading from the receptor pore to the inner chambers were the longest and the overlaying epidermal layers are the thickest. These results show that mormyromasts and the epidermis they are embedded in at both foveal regions differ specifically from those found on the rest of the body. The morphological specializations lead to functional specialization of the two foveae. J. Morphol., 2012. © 2012 Wiley Periodicals, Inc.     

Selecting representative model micro-organisms

Background  

Micro-biological research relies on the use of model organisms that act as representatives of their species or subspecies, these are frequently well-characterized laboratory strains. However, it has often become apparent that the model strain initially chosen does not represent important features of the species. For micro-organisms, the diversity of their genomes is such that even the best possible choice of initial strain for sequencing may not assure that the genome obtained adequately represents the species. To acquire information about a species' genome as efficiently as possible, we require a method to choose strains for analysis on the basis of how well they represent the species.     

Production of the lepidoptera-specific crystal protein by a local isolate of Bacillus thuringiensis

Summary A local isolate of Bacillus thuringiensis (B.t.81) produced crystal protein which was identified as a cry I gene of Class I. The synthesis and assembly of crystal complements were investigated at intervals throughout the growth cycle. Incubation temperature had a marked effect on toxin synthesis; production being the highest at 25°C and the lowest at 42°C. The mutants of B. t. 81, unable to synthesize crystal protein complements, have also been described.     

Seasonal plasticity in growth and development of the speckled wood butterfly, Pararge aegeria (Satyrinae)

Regulation of growth and development by photoperiod was studied in a population of the speckled wood butterfly, Purarge aegeria L. (Lepidoptera: Satyrinae), from southern Sweden. Individuals were reared in a range of photoperiodic regimes (9L. to 22L) and temperatures (13°C to 21° C). Plasticity was found for important life-history traits- generation time, growth rate and final weight and seasonal regulation of development in response to photoperiod was found to occur at two levels. Purarge aegeria hibernates as a third instar larva or in the pupal stage, cantering one of four major developmental pathways in response to photoperiod: (1) direct development in both the larval and pupal stages, (2) pupal winter diapause with or (3) without a preceding larval summer diapause, or (4) larval winter diapause. In addition to this high-level regulation of individual development, larval growth rate and pupal development rate also appear to be finally regulated by photoperiod within each major pathway. As photoperiods decreased from 22 h to 17 h at 17° C, growth rate among directly developing larvae increased progressively, as was the case for larva? developing according to a univoltine life cycle from 17 h to 14 h. At two photoperiods, 13 h and 16 h (corresponding to shifts between major pathways), both larval and pupal development were extremely variable with the fastest individuals developing directly and the slowest developing with a diapause. This indicates a gradual nature of diapause itself, suggesting that the two level may not he fundamentally different.     

Cladistic analysis of the subfamilies within the Tubificidae (Oligochaeta)

A hypothesis of phylogenetic relationships within the family Tubificidae is presented, based on a Wagner analysis of morphological characters in the different subfamilies. Two major lincages are recognized. One, including the subfamilies Tubificinae, Telmatodrilinae and Limnodriloidinae, is supported by a synapomorphic ability to form slender spermatozeugmata in the spermathecae; the other, including Rhyacodrilinae (paraphyletic), Phallodrilinae, and the (present family) Naididae, is supported by two synapomorphics, the possession of modified penial setae and numerous coelomocytes (the latter secondarily lost in the Phallodrilinae). Some implications for the classification of the Tubificidae are discussed.     

Iodine binding and peroxidase activity in the endostyle of Salpa fusiformis,Thalia democratica,Dolioletta gegenbauri and Doliolum nationalis (Tunicata,Thaliacea)

Summary The protothyroid region in the endostyles of four species of tunicates was examined by means of autoradiography and cytochemistry, at both the light and electronmicroscopic levels. To reveal the primary binding site for iodine, autoradiography was carried out on endostylar tissue from animals that had been incubated with high activity ¹²⁵I^- over a short period of time. The specific iodine binding enzyme, a peroxidase, was traced by its reaction with DAB. In accordance with previous findings, the iodinebinding cells proved to be the same as those containing the peroxidase. There were also strong indications of a secondary uptake of iodinated compounds and subsequent release into the body fluid. Together with the ultrastructural features, the data provided strong evidence indicating that these cells constitute a protothyroid region, which partly functions as an endocrine organ, possibly homologous with the vertebrate thyroid gland. Since the number of zones varied between the species, the numeration of the protothyroid region also varied. However, in all the examined endostyles, the protothyroid region was seen to be situated dorsolaterally to the glandular regions of the endostyle concerned with food capture.     

Kinetics of multiproduct acidogenic and solventogenic batch fermentations

Summary Large amounts of data indicated that most of the metabolic processes of the acidogenic (acid producing) and the solventogenic (solvent producing) fermentations were regulated by product accumulation. A simple unstructured model simulated microbial growth, product formation and substrate utilization in six different fermentations, where five different microorganisms produced various combinations of ten different products. Specific growth rates of these microorganisms decreased proportionally with overall product accumulation. The products were excreted in non-growth associated pattern. Excretion of some of these products were inhibited by the overall product accumulation similarly as the microbial growth. A substrate consumption model which considered the biomass and individually all the products as separate substrate sinks simulated the data satisfactorily.     

Immunohistochemical localization of porcine diazepam-binding inhibitor (DBI) to rat endocrine pancreas

Summary The occurrence of diazepam-binding inhibitor (DBI), isolated and characterized from porcine upper intestine, was examined in the pancreas of Sprague-Dawley albino rats using indirect immunofluorescence. The polypeptide was found in the endocrine Langerhans islets and, utilizing double-labelling controls, it was shown to be present within the peripherally located glucagon-containing cells. Regulation of islet hormone production may therefore be under DBI control.