Allozyme Variation in a Natural Population of the Nile Crocodile

Blood samples were collected for allozyme studies from 92 Crocodylusniloticus from the Runde River in Gonarezhou National Park,southern Zimbabwe. Two (glucose phosphate isomerase and erythrocyteacid phosphatase) of 27 protein coding loci were polymorphicwhen examined by starch-gel electrophoresis. This amount ofvariability is similar to that found in another crocodilian,Alligator mississippiensis and is not unusually low as has beenfound in a number of large vertebrates. In a single semi-isolatedpopulation, allele frequencies at both polymorphic loci werein Hardy-Weinberg equilibrium suggesting a random mating patternwith no severe bottleneck effect in the founding of this population.Population F-statistics suggest that panmixia exists withinand among the three main breeding sites studied.     

PAGODATROCHUS, A NEW GENUS FOR MINOLIA VARIABILIS H. ADAMS, 1873 (GASTROPODA: TROCHIDAE)

Nomenclaturel confusion surrounding the name Minolia variabilisH. Adams, 1873 is clarified. Joint consideration of overallshell morphology and radula structure indicates previous subfamilialand generic referral of the taxon to be incorrect. This necessitatesthe proposal of Pagodatrochus gen. nov. which is provisionallyplaced in the Gibbulinae. Trochus mariei Fischer, 1886, andMinolia eutyches Melvill, 1918, are shown to be synonyms. Lectotypesof the following species are designated and figured: M. eutyches,Gibbula holdsworthana G. & H. Nevill, 1871, and Vanitrochustragema (Melvill & Standen, 1896); the holotype of Trochusmariei is also figured. Minolia charmosyne Melvill, 1918, issynonymised with Gibbula holdsworthana G. & H. Nevill, 1871. (Received 24 April 1988; accepted 26 May 1988)     

Howard A. Schneiderman--Planetary Patriot

SYNOPSIS. This symposium on arthropod development is dedicatedto the memory of Howard A. Schneiderman, who died on December5, 1990. Howard devoted much of his professional life to researchon arthropods and was the author of numerous publications onthe developmental biology of moths and flies. At Case-WesternReserve University and at the University of California-Irvinehe founded research institutes devoted to developmental biologyon arthropods as well as other organisms. Howard Schneidermanchampioned the use of insect growth regulators, which derivedfrom his research on the chemistry and physiology of juvenilehormone, as environmentally innocuous methods of controllinginsect pests of our food and fiber. In recent years he was aproponent of the use of molecular biology to alter the plantgenome so that insect-resistant crops might be grown and therebyreduce the use of insecticides. His global perspective was evidentin his understanding of how biotechnology could be applied toworld agriculture. Moreover, he quickly achieved prominencein promoting industry-university relations in his capacity asSenior Vice President for Research and Development at the MonsantoCompany. The cooperation among academic and industrial institutionsthat he fostered stands as a model for such relationships. HowardSchneiderman's influence on science and its applications, andon the universityindustry interface was profound and will befelt for many years to come.     

Honest signalling,dominance hierarchies and body condition in House Sparrows Passer domesticus (Aves: Passeriformes) during acute coccidiosis

Parasitic infections may change the equilibrium between the costs and benefits of an animal for maintaining its status in a social group. Consequently, parasites may influence the social status of an animal in a group. The present study investigated whether acute infection with Isospora spp. has any effect on the social relationships (e.g. dominance hierarchy) of male house sparrows and how the infection influences their behaviour, immune status, and body condition. Furthermore, the study allowed us to examine how important the ‘badge of dominance’ is with respect to maintaining social status even when the actual condition is changing as a result of infection. The results obtained showed that an acute infection leads to changes in the dominance hierarchy of a social group and that body mass losses of birds depend on the achieved hierarchy status. A positive correlation between the badge size and male aggressiveness was only found during acute infection. In addition, we also found a relationship between cell‐mediated immune response and male aggressiveness during acute infection. This suggests that male badge size is not sufficient to maintain a given dominance position. On the other hand, badge size, a signal developed during the moult, appears to remain an informative and ‘honest’ signal several months later, reflecting the energy reserves of a bird faced with a demanding stressful situation such as acute infection. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 99 , 718–726.     

Nitrogen acquisition, PEP carboxylase, and cellular pH homeostasis: new views on old paradigms

The classic biochemical pH-stat model of cytosolic pH regulation in plant cells presupposes a pH-dependent biosynthesis and degradation of organic acids, specifically malic acid, in the cytosol. This model has been used to explain the higher tissue accumulation of organic acids in nitrate (NO₃^–)-grown, relative to ammonium (NH₄⁺)-grown, plants, the result of proposed cytosolic alkalinization by NO₃^– metabolism, and acidification by NH₄⁺ metabolism. Here, a critical examination of the model shows that its key assumptions are fundamentally problematic, particularly in the context of the effects on cellular pH of nitrogen source differences. Specifically, the model fails to account for proton transport accompanying inorganic nitrogen transport, which, if considered, renders the H⁺ production of combined transport and assimilation (although not the accumulation) to be equal for NO₃^– and NH₄⁺ as externally provided N sources. We show that the model's evidentiary basis in total-tissue mineral ion and organic acid analysis is not directly relevant to subcellular (cytosolic) pH homeostasis, while the analysis of the ionic components of the cytosol is relevant to this process. A literature analysis further shows that the assumed greater activity of the enzyme phosphoenolpyruvate (PEP) carboxylase under nitrate nutrition, which is a key characteristic of the biochemical pH-stat model as it applies to nitrogen source, is not borne out in numerous instances. We conclude that this model is not tenable in its current state, and propose an alternative model that reaffirms the anaplerotic role of PEP carboxylase within the context of N nutrition, in the production of carbon skeletons for amino acid synthesis.     

Responses of net ecosystem CO2 exchange in managed grassland to long-term CO2 enrichment, N fertilization and plant species

The effects of elevated pCO₂ on net ecosystem CO₂ exchange were investigated in managed Lolium perenne (perennial ryegrass) and Trifolium repens (white clover) monocultures that had been exposed continuously to elevated pCO₂ (60 Pa) for nine growing seasons using Free Air CO₂ Enrichment (FACE) technology. Two levels of nitrogen (N) fertilization were applied. Midday net ecosystem CO₂ exchange (mNEE) and night-time ecosystem respiration (NER) were measured in three growing seasons using an open-flow chamber system. The annual net ecosystem carbon (C) input resulting from the net CO₂ fluxes was estimated for one growing season. In both monocultures and at both levels of N supply, elevated pCO₂ stimulated mNEE by up to 32%, the exact amount depending on intercepted PAR. The response of mNEE to elevated pCO₂ was larger than that of harvestable biomass. Elevated pCO₂ increased NER by up to 39% in both species at both levels of N supply. NER, which was affected by mNEE of the preceding day, was higher in T. repens than in L. perenne. High N increased NER compared to low N supply. According to treatment, the annual net ecosystem C input ranged between 210 and 631 g C m⁻² year⁻¹ and was not significantly affected by the level of pCO₂. Low N supply led to a higher net C input than high N supply. We demonstrated that at the ecosystem level, there was a long-term stimulation in the net C assimilation during daytime by elevated pCO₂. However, because NER was also stimulated, net ecosystem C input was not significantly increased at elevated pCO₂. The annual net ecosystem C input was primarily affected by the amount of N supplied.     

Follow up of women with a history of mildly abnormal cervical smears which have returned to normal without treatment

The progress of 124 women with at least two negative cervical smears following a history of mildly abnormal smears for which no treatment had been given was compared with 106 women with negative smears and a clinical history of genital warts or herpes virus infection and 460 age-matched controls. After 4 years, excluding those for whom there was no follow up, 5.8% of those with a history of abnormal smears, none of those with a clinical history of genital warts or herpes virus and 1.1% of controls had developed histological evidence of at least cervical intraepithelial neoplasia grade III (CINIII) when referred for investigation of subsequent abnormal smears; one woman, from the control group, had developed invasive cervical cancer. Women with two negative smears after a history of abnormal smears who subsequently developed CINIII were more likely to have had a previous smear reported as moderate or mild-moderate dyskaryosis (2/6) compared with those whose follow up was negative (2/89). the results suggest that two negative cervical smears may not necessarily indicate that a lesion has regressed, but that a clinical history of genital warts or herpes virus infection should not be an indication for increased surveillance.     

The importance of tail length for habitat use in the Bearded Tit Panurus biarmicus: an experimental study

The original function of the tail in birds is likely to be related to flight performance or bipedal locomotion. In this study, we examined the role of the long graduated tail of male Bearded Tits Panurus biarmicus , focusing on the function of the tail as a balancing organ when moving in reeds, the habitat in which this species spends its whole life. We performed an aviary experiment using males with shortened, elongated or control (unmanipulated) tails and recorded their use of different reed heights and preferences for different sitting postures. Tail manipulation did not change the use of different reed heights between treatments. The head-up posture was the preferred sitting technique and was independent of tail length. We found that males with elongated tails showed less variation in the use of different sitting postures along the reed. In addition, the use of the 'straddle' sitting technique varied in relation to tail length, tending to be less frequent when tails were experimentally shortened. These results suggest that tail length influences how Bearded Tits move and may exploit their habitat. The role of the tail as a balancing organ when using small twigs or branches may have been underestimated.