Dendrometer and intra-annual tree growth: What kind of information can be inferred?

Dendrometer measurements provide time series composed of the rhythm of water storage fluctuations over the year and seasonal tree growth. For slow-growing trees, however, difficulties have been found in the identification of crucial events such as growth onset, stem growth period and cessation, rendering it necessary to define what can be measured and at which time scale. Time scale means the time interval (from one day to one month) at which stem radius variation is extracted. In this study, two conifer species were monitored by an automatic band dendrometer to assess several time scales and analysis approaches. Data were collected from 8 trees of Picea abies (L.) Karst and Larix decidua L., growing at 1020 and 2080 m a.s.l. in the eastern Italian Alps, from 2000 to 2003. Time series of stem radius variation were extracted with different approaches, such as the stem cycle, daily mean and daily maximum. Several approaches can be used, as very similar time series of stem radius variations were produced with high coefficients of correlation among the series. At lower altitude, the approximate onset was identified at the beginning of May with a 10-day time scale, when the distribution of stem radius variation differed from zero. The main growth period, from May to June–July, corresponded mainly with earlywood cell formation. At higher altitude, a time scale of at least 15 days facilitated identification of the main period of stem growth only, corresponding with earlywood cell formation. Even if latewood cells were produced in August at both altitudes, the variability in stem radius changes was higher than the amount of growth in terms of cell-wood production. For a slow-growing species in a cold environment, an understanding of the growth period, assessed with several time scales, is necessary when using time series of stem radius variation to assess growth and climate relationships. The period used for growth and climate analysis should correspond only with the main period of stem growth.     

Spiroplasma infection in Drosophila melanogaster: What is the advantage of killing males?

Male-killing bacteria are maternally inherited agents that cause death of sons of infected females. Their transmission rate is commonly high but imperfect and also sensitive to different environmental factors. Therefore, the proportion of infected females should be reduced in each generation. In order to explain male-killers spread and persistence in host population, a mechanism resulting in the relative increase of infected females must outweigh the losses caused by the imperfect transmission. The resource release hypothesis states that the males’ death results in increased resources available to sibling females which would otherwise be used by their male siblings. Infected females are then expected: to be larger than uninfected females in natural populations; or to have higher viability; or to have shorter development times; or any combination of these outcomes. Here, we tested the resource release hypothesis by measuring body size of infected and uninfected wild-caught Drosophila melanogaster females and carried out other fitness related measures in the laboratory. Wild-caught infected females produced more daughters than uninfected females in their first days in the laboratory. However, although no significant difference in viability was found in a controlled experiment with infected and uninfected flies from a standard laboratory strain, there was a decrease in development time probably mediated by reduced competition. Fitness effects conditioned by the host genetic background are pointed out as a possible explanation for this difference between wild and laboratory flies. Our findings are discussed in the context of the resource advantage hypothesis.     

Cordaites schatzlarensis sp. nov. and Samaropsis newberryi (Andrews) Seward from the Westphalian (Carboniferous) of the ?aclé? area (Czech Republic)

The monotonous cordaitalean leaves are usually difficult to determine as leaf shape and venation can be similar in many species. Therefore cuticular analysis is an important method for distinguishing cordaitalean leaves. Pennsylvanian Cordaites schatzlarensis nov. sp. comes from the ?aclé? locality in the Intrasudetic Basin, Czech Republic. It has been found in mudstone accompanying the upper coal seams No. 9 and 10 of the Jan Šverma Coals, Lampertice Member, ?aclé? Formation and are late Duckmantian in age. The leaves of Cordaites schatzlarensis are lanceolate, amphistomatic. Stomata of the adaxial epidermis are scarce, isolated, or in very short stomatal rows. In contrast, the density of stomata on the abaxial cuticle is high and stomata are arranged into single or double stomatal rows. The cuticles of C. schatzlarensis are comparable with the Chinese Upper Permian C. baodeensis Ge. Leaves can be narrow, comparable to French Bolsovian Dorycordaites zeilleri Ledran, or relatively wide. Accompanying big seeds more than 5 cm in diameter are attributed to Samaropsis newberryi (Andrews) Seward. The pith casts Artisia Sternberg were found in sandy channel fill deposits.     

Decreased impacts of the 2003 heat waves on mortality in the Czech Republic: an improved response?

The paper examines impacts on mortality of heat waves in 2003, the hottest summer on record in the Czech Republic, and compares them with previous similar events. While most summer heat waves over the period since 1986 were associated with significantly elevated mortality, this was not the case for three out of the four heat waves in 2003. The relatively weak mortality response was particularly noteworthy for the most severe heat wave which occurred in the first 10 days of August 2003 and resulted in enormous excess mortality in some western European countries. A mortality displacement effect and short-term adaptation to heat contributed to the reduced mortality impacts of the heat waves that followed after previous relatively warm periods. However, the decreased mortality response of the 2003 heat waves compared to previous heat waves in the 1990s is also likely to have arisen from positive health-care and other socio-economic changes in the post-communist central European region over the past decade, as well as a better public awareness of heat-related risks due to enhanced media coverage and regular biometeorological forecast and warnings.     

What are 60 warblers worth? Killing in the name of conservation

Ecological research sometimes entails animal suffering and even animal killing. The ethical appropriateness of animal suffering and killing in conservation research may entail considerations that differ from many other kinds of research. This is true, insomuch as conservation research is specifically motivated by an ethical premise: an appreciation for non-human life. In striking contrast with other academic fields (e.g. medicine), however, the ethical dimension of conservation research is only rarely discussed. When it is discussed, it tends to be characterized by logical errors. These errors are important because they are general (i.e. both common and with far-reaching implications), and they are easily made by intelligent people; especially those with no formal training in ethics or logic. Failure to recognize these errors could stymie efforts to increase the ethical quality of ecological research conducted in the name of conservation.
We take advantage of a recently published dialogue concerning the ethical appropriateness of a specific field experiment that entailed killing black-throated blue warblers, Dendroica caerulescens . Both sides of this debate exemplify the kinds of errors to which we refer. In this paper we briefly review the arguments presented on each side of this debate, highlight their mistakes, and indicate necessary corrections. We argue that: (1) compliance with animal research regulations, while important, inadequately accommodates the ethical aspects of animal research, and (2) individual ecologists ought to understand themselves what does and does not represent sound and valid arguments for ethical decisions. Finally, we discuss how any ecological researcher might begin to apply our analysis to his or her own research.     

UV-induced changes in the skin: can they be repaired?

The damaging effects of UVB light have been described previously and include a number of changes to multiple cell types. At previous meetings of this society, we have shown that Langerhans' cells are the most susceptible to UVB induced damage which can be shown as ultrastructural changes in dendrites, nucleus and cytoplasm by transmission electron microscopy. We have also shown that their patterns of migration from skin to regional lymph node and their ability to present antigens to autologous T cells have been profoundly altered by UVB irradiation. The aim of this work was to establish if it was possible to reverse any of the damage done to Langerhans' cells by UVB exposure by topical application of a DNA repair enzyme such as T4N5 endonuclease. These experiments were undertaken in a sheep model that allowed collection of cells as they migrate from the skin. This allowed for a direct examination of the migration characteristics and ultrastructural features of all Langerhans' cells before, during, and for 2 weeks after exposure to a single dose of UVB. Results obtained from this project indicate that treatment by topical application of DNA repair enzyme immediately after UVB irradiation may restore a number of normal immune parameters associated with the structure and function of migrating Langerhans' cells. It appears that there is a dose related correction of the increased tempo of cell migration and some improvements in the number of ultrastructurally damaged Langerhans' cells have also been associated with application of higher doses of DNA repair enzyme. These preliminary findings indicate that some potential therapeutic benefits are associated with the use of such agents in reversing the immunological damage caused by exposure to erythemal doses of UVB light.     

UV-induced changes in the skin: can they be repaired?

Abstract

The damaging effects of UVB light have been described previously and include a number of changes to multiple cell types. At previous meetings of this society, we have shown that Langerhans' cells are the most susceptible to UVB induced damage which can be shown as ultrastructural changes in dendrites, nucleus and cytoplasm by transmission electron microscopy. We have also shown that their patterns of migration from skin to regional lymph node and their ability to present antigens to autologous T cells have been profoundly altered by UVB irradiation.

The aim of this work was to establish if it was possible to reverse any of the damage done to Langerhans' cells by UVB exposure by topical application of a DNA repair enzyme such as T4N5 endonuclease. These experiments were undertaken in a sheep model that allowed collection of cells as they migrate from the skin. This allowed for a direct examination of the migration characteristics and ultrastructural features of all Langerhans' cells before, during, and for 2 weeks after exposure to a single dose of UVB.

Results obtained from this project indicate that treatment by topical application of DNA repair enzyme immediately after UVB irradiation may restore a number of normal immune parameters associated with the structure and function of migrating Langerhans' cells. It appears that there is a dose related correction of the increased tempo of cell migration and some improvements in the number of ultrastructurally damaged Langerhans' cells have also been associated with application of higher doses of DNA repair enzyme. These preliminary findings indicate that some potential therapeutic benefits are associated with the use of such agents in reversing the immunological damage caused by exposure to erythemal doses of UVB light.     

What determines the growth of individual castes in social trematodes?

Phenotypic diversification among colony members often leads to formation of physical castes which are morphologically specialised for particular tasks within the colony. The relative abundance of these castes and their body sizes represent two key aspects of the demography of a colony that may reflect the colony’s needs and conditions, and ultimately influence its survival and reproductive success. In a recently discovered social trematode, Philophthalmus sp., which exhibits a reproductive division of labour, the role of competition and colony composition in shaping reproductive success and behaviour of colony members has been documented. As body size variation within physical castes often influences colony efficiency, we investigated how the growth of reproductive and non-reproductive morphs of Philophthalmus sp. responds to competitive pressure, and to other attributes of colony demography such as colony size and composition. Our survey of a natural population and in vitro experiments demonstrate that the growth of reproductive colony members reflects the interaction between colony composition and the presence of a competitor, while the non-reproductive members simply grow larger in the presence of the intra-host competitor, Maritrema novaezealandensis. Furthermore, the close association between the volume and reproductive capacity of the reproductive members corroborates an adaptive value of colony member size in determining the fitness of the trematode colony as a whole. The present study is the first to demonstrate a fitness consequence, and identify the determinants, of the growth of colony members in social trematodes.     

Is auxin the repressor signal of branch growth in apical control?

"Apical control" is the repression of branch growth by a higher dominating branch or shoot. There has been some confusion in the literature concerning the meaning and causal mechanisms of this correlative phenomenon with those of "apical dominance," which term is often used in a strict sense to connote the repression of the initiation of axillary bud outgrowth by an active shoot apex. Although the term "apical control" is most commonly employed with respect to woody species, this phenomenon also widely occurs in herbaceous plants. Because of the strong evidence for a role of auxin as a repressor signal in apical dominance and partly because of this lack of distinction in terminology, a similar role for auxin in apical control is often assumed in spite of the obvious acropetal auxin transport difficulty and the lack of direct evidence for the acropetal transport of any inhibitor influence. In the present study with the herbaceous Ipomoea nil, it has been clearly demonstrated that while exogenous auxin (1% NAA) strongly restores apical dominance in the Thimann-Skoog experiment, auxin treatments to decapitated dominant shoots do not, in any observable way, restore apical control in lower dominated branches. Hence, in this fast-growing species, the hypothesis for the role of auxin as a repressor signal for apical control is not supported.     

Misunderstanding in the classification of diabetes mellitus. What's in a name?

To assess whether physicians, residents, medical students, hospital diagnosis coders, and patients properly use the designations insulin-dependent diabetes mellitus (IDDM) and non-insulin-dependent diabetes mellitus (NIDDM) that were established by criteria of the National Diabetes Data Group, we reviewed clinic and hospital records and administered questionnaires. Although essentially all cases of true IDDM were identified as such and most cases of NIDDM not requiring insulin therapy were correctly identified by all groups, patients with NIDDM on insulin therapy were misidentified as having IDDM by 38% of residents in internal medicine clinics and 68% of primary care and surgical subspecialty residents. On a survey, of 22 patients with NIDDM on insulin therapy, 17 (77%) considered themselves to have IDDM. Thus, patients who have NIDDM by the established criteria who are on insulin therapy are commonly mislabeled as having IDDM. We present an approach for dealing with this problem by adapting nomenclature focusing on insulin deficiency and resistance. It would probably also be helpful to separately identify the subset of patients with "insulin-deficient diabetes" who are ketosis-prone. It is important to use immunologic profiling (islet cell antibody testing) and insulin sensitivity or deficiency testing (C-peptide levels).     

What may be the anatomical basis that secretin can improve the mental functions in autism?

Autism was first described and characterized as a behavioral disorder more than 50 years ago. The major abnormality in the central nervous system is a cerebellar atrophy. The characteristic histological sign is a striking loss or abnormal development in the Purkinje cell count. Abnormalities were also found in the limbic system, in the parietal and frontal cortex, and in the brain stem. The relation between secretin and autism was observed 3 years ago. Clinical observations by Horváth et al. [J. Assoc. Acad. Minor. Physicians 9 (1998) 9] supposed a defect in the role of secretin and its receptors in autism. The aim of the present work was to study the precise localization of secretin immunoreactivity in the nervous system using an immunohistochemical approach. No secretin immunoreactivity was observed in the forebrain structures. In the brain stem, secretin immunoreactivity was observed in the mesencephalic nucleus of the trigeminal nerve, in the superior olivary nucleus, and in scattered cells of the reticular formation. The most intensive secretin immunoreactivity was observed in the Purkinje cells of the whole cerebellum and in some of the neurons of the central cerebellar nuclei. Secretin immunoreactivity was also observed in a subpopulation of neurons in the primary sensory ganglia. This work is the first immunohistochemical demonstration of secretin-immunoreactive elements in the brain stem and in primary sensory ganglia.     

Looking under the bonnet of conservation conflicts: can neuroscience help?

Neuroscience—a branch of biology seemingly distant from nature/wildlife conservation is revolutionised by the ability to visualise the brain activity of humans. Using positron emission tomography (PET), functional magnetic resonance imaging (fMRI) and magnetoencephalograhy (MEG), neuroscience is revealing how humans are wired in ways that have bearing on any problem that involves values; and nature/wildlife conservation is surely one of those. Understanding how the human brain represents and processes morality and sacred values, and responds to conflicts could shed a powerful light on nature/wildlife conservation tactics. Conservation polices typically involve utilitarian considerations. However, research shows that conservation policies based solely on utilitarian considerations are likely to fail as the neurological process of rights and wrongs grates against the process of cost and benefits.     

Environmental parasitology: What can parasites tell us about human impacts on the environment?

There are a variety of ways that environmental changes affect parasites, suggesting that information on parasites can indicate anthropogenic impacts. Parasitism may increase if the impact reduces host resistance or increases the density of intermediate or definitive hosts. Parasitism may decrease if definitive or intermediate host density declines or parasites suffer higher mortality directly (eg. from toxic effects on parasites) or indirectly (infected hosts suffer differentially high mortality). Although these scenarios are opposing, they can provide a rich set of predictions once we understand the true associations between each parasite and impact. In this review, Kevin Lafferty discusses how parasite ecologists have used and can use parasites to assess environmental quality.     

Aging and neural control of the GI tract. II. Neural control of the aging gut: can an old dog learn new tricks?

There has been a dramatic increase in funding available for aging research, primarily due to the fact that answers to questions on aging are likely to have a major impact on the well-being and healthy aging of the world's population for decades to come. The incidence of certain gastrointestinal problems, such as dysphagia and constipation, increases dramatically with age. Changes in gastrointestinal neuromuscular function with aging have been demonstrated in both human and animal models of aging. This article focuses on recent advances in our knowledge of the effects of aging on gastrointestinal function, treatment options, and future opportunities for research.     

Inertial shear forces and the use of centrifuges in gravity research. What is the proper control?

Centrifuges are used for 1 x g controls in space flight microgravity experiments and in ground based research. Using centrifugation as a tool to generate an Earth like acceleration introduces unwanted inertial shear forces to the sample. Depending on the centrifuge and the geometry of the experiment hardware used these shear forces contribute significantly to the total force acting on the cells or tissues. The inertial shear force artifact should be dealt with for future experiment hardware development for Shuttle and the International Space Station (ISS) as well as for the interpretation of previous space-flight and on-ground research data.