Biomechanism of resistance to retinal injury in woodpecker’s eyes

Retinal injury is the most common ocular impairment associated with shaken baby syndrome(SBS), which could lead to vision loss and blindness. However, a woodpecker does not develop retinal hemorrhages or detachment even at a high acceleration of 1,000×g during pecking. To understand the mechanism of retinal injury and its resistance strategy, we put insight into the special ability of the woodpecker to protect the retina against damage under acceleration–deceleration impact. In this study, the structural and mechanical differences on the eyes of the woodpecker and human were analyzed quantitatively based on anatomical observation. We developed finite element eye models of the woodpecker and human to evaluate the dynamic response of the retina to the shaking load obtained from experimental data. Moreover, several structural parameters and mechanical conditions were exchanged between the woodpecker and human to evaluate their effects on retinal injury in SBS. The simulation results indicated that scleral ossification, lack of vitreoretinal attachment, and rotational acceleration–deceleration impact loading in a woodpecker contribute to the resistance to retinal injuries during pecking. The above mentioned special physical structures and mechanical behavior can distribute the high strain in the posterior segment of the woodpecker's retina, which decrease the risk of retinal injury to SBS.     

Conservation genetics of Blanding’s turtle and its application in the identification of evolutionarily significant units

Blanding’s turtle is a North American freshwater turtle whose main range occurs south of the Great Lakes; disjunct populations occur east of the Appalachian Mountains from New York to Nova Scotia. The species is listed as threatened or endangered in most of its range. We employed five variable microsatellites to examine samples of 300 individuals in 12 populations. Estimates of F _ST based on pairwise comparisons of populations ranged from 0.000 to 0.465. Phylogenetic analysis of these F _ST values reveals that the Appalachian Mountains and the Hudson River appear to present major barriers to gene flow in Blanding’s turtle. The extent of fine-scale genetic structure previously reported in the Nova Scotian populations was not found in other parts of the species’ range. We recommend that populations separated by the Appalachian Mountains as well as the highly disjunct Nova Scotian populations of Blanding’s turtle be recognized as evolutionarily significant units.     

Neurophysiological aspects of the regulation of the head’s position in the normal state and left- and right-sided forms of spasmodic torticollis

We have studied the spatiotemporal distribution of coherent EEG links in 10 healthy right-handed subjects under the conditions of comfortable wakefulness with a straight position of the head and with the head voluntarily turned to fixed left and right positions. The computations were made separately in each standard range of EEG frequencies (Δ, θ, α, and β). The results were compared with the data obtained during studies of right-handed patients with right-sided (RS, n = 9) and left-sided (LS; n = 8) forms of spasmodic torticollis (ST). It has been shown that, upon a voluntary right turn of the head, the number of strong and moderate coherent EEG links in healthy subjects increases considerably more than upon a left turn. This may be accounted for by the greater functional importance of the control of the right part of the visual space as the area of manipulation of the dominant hand. In patients with RS ST, the number of intra- and interhemispheric strong and moderate coherent EEG links increased in all four frequency ranges, as compared to healthy subjects, upon the right turn of the head. In patients with LS ST, the spatial structure of the bioelectric potential field of the brain is less reorganized upon the voluntary left turn of the head as compared to the level of coherent EEG links in healthy subjects. Presumably, this phenomenon reflects a stronger insufficiency of neurophysiological mechanisms of postural control and compensation for its disturbances in patients with the LS form of ST, which results in a more severe disability as compared to patients with right-sided ST.     

Ubiquitin-protein ligase parkin and its role in the development of Parkinson’s disease

Parkin is a protein encoded by the corresponding parkin gene. It exhibits ubiquitin-protein ligase activity. In this review, we analyze domain structure, substrate specificity, subcellular localization of parkin, and regulation of its activity. Then we discuss data on the effects of various mutations in the parkin gene on structure and functions of this protein and results obtained with parkin knock-out animals. Better understanding of parkin biochemistry, its compartmentalization, functions, and altered functions would help the development of new approaches for the treatment of both inherited and sporadic cases of Parkinson’s disease. Published in Russian in Biokhimiya, 2006, Vol. 71, No. 8, pp. 1050–1061.     

The Neurobiology of LRRK2 and its Role in the Pathogenesis of Parkinson’s Disease

Leucine-rich repeat kinase 2 (LRRK2) is a large, widely expressed protein of largely unknown function. Mutations in the gene encoding LRRK2 have been linked to multiple diseases, including a prominent association with familial and sporadic Parkinson’s disease (PD), as well as inflammatory bowel disorders such as Crohn’s disease. The LRRK2 protein possesses both kinase and GTPase signaling domains, as well as multiple protein interaction domains. Experimental studies in both cellular and in vivo models of mutant LRRK2-induced neurodegeneration have given clues to potential function(s) of LRRK2, yet much remains unknown. For example, while it is known that intact kinase and GTPase activity are required for mutant forms of the protein to trigger cell death, the specific targets of these enzymatic activities that mediate the death of neurons are not known. In this review, we discuss the evidence linking LRRK2 to various cellular/neuronal activities such as extrinsic death and inflammatory signaling, lysosomal protein degradation, the cytoskeletal system and neurite outgrowth, vesicle trafficking, mitochondrial dysfunction, as well as multiple points of interaction with several other genes linked to the pathogenesis of PD. In order for more effective therapeutic strategies to be envisioned and implemented, the mechanisms underlying LRRK2-mediated neurodegeneration need to be better characterized. Furthermore, insights into LRRK2-associated PD pathogenesis can potentially advance our understanding of the more common sporadic forms of PD.     

Assessing the impact of fostering on children’s outcomes in Niger

This article measures the impact of fostering on children’s outcomes in Niger. We estimate a simultaneous equations model with three outcomes for children (school attendance, hours of market work and hours of domestic work) and a treatment variable (fostering). Nonlinearity provides identification by functional form of the causal effect of fostering. We further use information on the historical level of community integration of the child’s ethnicity and the relative importance of the ethnicity in the neighborhood to build a plausibly exogenous exclusion restriction in order to correct for the potential endogeneity of fostering. Our results sustain the overall conclusion that fostering has a positive impact on children’s school attendance and hours of domestic work. However, while foster boys and girls are both engaged in longer hours of domestic labor, only foster boys are advantaged in terms of schooling.     

The Role of Presenilin and its Interacting Proteins in the Biogenesis of Alzheimer’s Beta Amyloid

The biogenesis and accumulation of the beta amyloid protein (Aβ) is a key event in the cascade of oxidative and inflammatory processes that characterises Alzheimer’s disease. The presenilins and its interacting proteins play a pivotal role in the generation of Aβ from the amyloid precursor protein (APP). In particular, three proteins (nicastrin, aph-1 and pen-2) interact with presenilins to form a large multi-subunit enzymatic complex (γ-secretase) that cleaves APP to generate Aβ. Reconstitution studies in yeast and insect cells have provided strong evidence that these four proteins are the major components of the γ-secretase enzyme. Current research is directed at elucidating the roles that each of these protein play in the function of this enzyme. In addition, a number of presenilin interacting proteins that are not components of γ-secretase play important roles in modulating Aβ production. This review will discuss the components of the γ-secretase complex and the role of presenilin interacting proteins on γ-secretase activity. Special issue dedicated to John P. Blass.     

Effect of variable periodontal ligament thickness and its non-linear material properties on the location of a tooth’s centre of resistance

In orthodontics, the 3D translational and rotational movement of a tooth is determined by the force–moment system applied and the location of the tooth’s centre of resistance (CR). Because of the practical constraints of in-vivo experiments, the finite element (FE) method is commonly used to determine the CR. The objective of this study was to investigate the geometric model details required for accurate CR determination, and the effect of material non-linearity of the periodontal ligament (PDL). A FE model of a human lower canine derived from a high-resolution µCT scan (voxel size: 50 µm) was investigated by applying four different modelling approaches to the PDL. These comprised linear and non-linear material models, each with uniform and realistic PDL thickness. The CR locations determined for the four model configurations were in the range 37.2–45.3% (alveolar margin: 0%; root apex: 100%). We observed that a non-linear material model introduces load-dependent results that are dominated by the PDL regions under tension. Load variation within the range used in clinical orthodontic practice resulted in CR variations below 0.3%. Furthermore, the individualized realistic PDL geometry shifted the CR towards the alveolar margin by 2.3% and 2.8% on average for the linear and non-linear material models, respectively. We concluded that for conventional clinical therapy and the generation of representative reference data, the least sophisticated modelling approach with linear material behaviour and uniform PDL thickness appears sufficiently accurate. Research applications that require more precise treatment monitoring and planning may, however, benefit from the more accurate results obtained from the non-linear constitutive law and individualized realistic PDL geometry.     

Role of zinc and copper ions in the pathogenetic mechanisms of Alzheimer’s and Parkinson’s diseases

Disbalance of zinc (Zn²⁺) and copper (Cu²⁺) ions in the central nervous system is involved in the pathogenesis of numerous neurodegenerative disorders such as multisystem atrophy, amyotrophic lateral sclerosis, Creutzfeldt-Jakob disease, Wilson-Konovalov disease, Alzheimer’s disease, and Parkinson’s disease. Among these, Alzheimer’s disease (AD) and Parkinson’s disease (PD) are the most frequent age-related neurodegenerative pathologies with disorders in Zn²⁺ and Cu²⁺ homeostasis playing a pivotal role in the mechanisms of pathogenesis. In this review we generalized and systematized current literature data concerning this problem. The interactions of Zn²⁺ and Cu²⁺ with amyloid precursor protein (APP), β-amyloid (Abeta), tau-protein, metallothioneins, and GSK3β are considered, as well as the role of these interactions in the generation of free radicals in AD and PD. Analysis of the literature suggests that the main factors of AD and PD pathogenesis (oxidative stress, structural disorders and aggregation of proteins, mitochondrial dysfunction, energy deficiency) that initiate a cascade of events resulting finally in the dysfunction of neuronal networks are mediated by the disbalance of Zn²⁺ and Cu²⁺.     

Role of the microtubule-associated TPPP/p25 in Parkinson’s and related diseases and its therapeutic potential

Introduction: The discovery and development of therapeutic strategies for the treatments of Parkinson’s disease (PD) and other synucleinopathies are limited by a lack of understanding of the pathomechanisms and their connection with different diseases such as cancers.

Areas covered: The hallmarks of these diseases are frequently multifunctional disordered proteins displaying moonlighting and/or chameleon features, which are challenging drug targets. A representative of these proteins is the disordered Tubulin Polymerization Promoting Protein (TPPP/p25) expressed specifically in oligodendrocytes (OLGs) in normal brain. Its non-physiological level is tightly related to the etiology of PD and Multiple System Atrophy (TPPP/p25 enrichment in inclusions of neurons and OLGs, respectively), multiple sclerosis (TPPP/p25-positive OLG destruction), as well as glioma (loss of TPPP/p25 expression). The established anti-proliferative potency of TPPP/p25 may raise its influence in cancer development. The recognition that whereas too much TPPP/p25 could kill neurons in PD, but its loss keeps cells alive in cancer could contribute to our understanding of the interrelationship of ‘TPPP/p25 diseases’.

Expert commentary: The knowledge accumulated so far underlines the key roles of the multifunctional TPPP/p25 in both physiological and diverse pathological processes, consequently its validation as drug target sorely needs a new innovative strategy that is briefly reviewed here.     

Ant biodiversity and its environmental predictors in the North Kimberley region of Australia’s seasonal tropics

Northern Australia supports the world’s largest estate of undeveloped tropical savannas, but previous studies of ant diversity in the region have covered only a fraction of its land area and habitat diversity. We assess patterns of ant species and functional diversity, their environmental predictors, and biogeographic significance in the central North Kimberley region of Australia’s seasonal tropics. Pitfall traps were used to sample ants at 69 plots in representative savanna habitats, collecting a total of 158 species from 30 genera. Total richness was estimated to be as high as 237 species. At least 29 species across 12 genera appear to have been collected for the first time. Only a single invasive ant was recorded from the study area. Based on cluster analysis we identified six compositionally distinct ant communities, each associated with a combination of vegetation type and underlying geology. Species richness and functional diversity was highest in savanna woodlands and grasslands on sandstone-derived soils, with increasing richness also predicted by a lower mean daily temperature range, a more complex understorey, and lower precipitation seasonality. The abundance of nearly all commonly trapped species was related to temperature, moisture, and habitat variables, although these relationships were highly idiosyncratic. Nearly 40 % of the collected species are known only from the North Kimberley region. The high level of endemism, together with the lack of introduced ant species, identifies the North Kimberley ant fauna as having outstanding biodiversity value. Our identification of ant community types based on mappable soil and vegetation units provides a basis for predicting ant distribution throughout the broader region, and therefore contributing to regional conservation planning and management.     

Genetics,development and composition of the insect head – A beetle’s view

Many questions regarding evolution and ontogeny of the insect head remain open. Likewise, the genetic basis of insect head development is poorly understood. Recently, the investigation of gene expression data and the analysis of patterning gene function have revived interest in insect head development. Here, we argue that the red flour beetle Tribolium castaneum is a well suited model organism to spearhead research with respect to the genetic control of insect head development. We review recent molecular data and discuss its bearing on early development and morphogenesis of the head. We present a novel hypothesis on the ontogenetic origin of insect head sutures and review recent insights into the question on the origin of the labrum. Further, we argue that the study of developmental genes may identify the elusive anterior non-segmental region and present some evidence in favor of its existence. With respect to the question of evolution of patterning we show that the head Anlagen of the fruit fly Drosophila melanogaster and Tribolium differ considerably and we review profound differences of their genetic regulation. Finally, we discuss which insect model species might help us to answer the open questions concerning the genetic regulation of head development and its evolution.     

Measurement of the chlorophyll fluorescence induction kinetics with a 10 µs time resolution and its application in the forest decline research

Summary Measurement methods are described which determine the initial phase of the fluorescence induction kinetics with a maximum time resolution of 10 µs simultaneously for the two fluorescence componentsF ₆₈₅(t) andF ₁₃₀(t) selected by filters at the wavelengths 685 nm and 730 nm, respectively. The excitation light provided by a He-Ne laser (632.8 nm) is switched on within 0.3 µs (maximum intensityI _e=12 mW/cm²).F _o,F _p, andF _s, the initial-, peak-, and steady-state intensity and the initial valueR _o of the ratioR(t)=F ₇₃₀(t)/F ₆₈₅(t) can accurately be determined as well as the initial time derivativeF _o ^* of the fluorescence intensity.F _o andF _o ^* are related to the quantum yield _a of the antenna and to the photochemical quantum yield _pc, respectively. Spruce, oak, birch, poplar, and soy bean show a decline ofR(t) fromR _o to a first minimumR _b at some 10 ms which has a similar value as the second minimumR _p in the time range of seconds. Furthermore, the initial valueR _o and the steady-state valueR _S ofR(t) are also very similar. Measurements on spruce with water deficiency and with varying excitation light intensityI _e show effects on the initial phase of the fluorescence induction kinetics. Further measurements on spruce of different damage classes indicate that for the current year's needles the ratioF _p/F_o, is the most sensitive parameter to differentiate between the damage classes and thatF _o/F_s andR _o/R_b are also affected. As demonstrated by measurements on leaves of soy beans, the initial decrease ofR(t) fromR _o toR _b originates from a change of the fluorescence spectrum because no change of the leaf transmission can be observed in the time range between 10 µs and 1 ms.     

The impact of time of day on the gait and balance control of Alzheimer’s patients

Alzheimer’s patients suffer from circadian dysregulation. The aim of this study was to examine the evolution of balance control and gait at different times of the day (11:00, 14:00, 18:00) in order to identify whether Alzheimer’s patients were more likely to fall at certain periods of the day. Spatio-temporal parameters of centre of foot pressure displacements were measured with a force platform and spatio-temporal parameters of walking were evaluated with a gait analysis device. The results highlighted that balance control was worse in the evening and the afternoon than in the morning. Furthermore, the walking speed was faster and support duration, swing duration and cycle duration were shorter in the evening than in the morning and afternoon. The combined analysis of balance control and gait parameters revealed that balance control and walking are concomitantly altered in the evening which increases the fall risk in the evening, in comparison with the morning, for Alzheimer’s patients.     

The fertility of women Poland in the period of trasformation of the political and economics system (the 80’s and 90’s)

Wielkopolska (western Poland) is a region, with good reason, called the main food base of Poland. All indices of agricultural production have always been there (since 19th century) much higher than elsewhere in the country (Ratajczak 1977/1978, Buszko 1984, Gorzelak 1989, Czyzewski et al. 1992; table 1). Such a situation had a beneficial effect on the amount of the income generated by a family of Wielkopolska and, thus, decided on its better financial status. Additionally, rural inhabitants of this region have always been characterised by a more advantageous educational structure in comparison with people of other Polish villages. Generally, it is easy to detect the relationship between the life standard, the level of education and family planning. The aim of this paper is to assess fertility of women from villages of Wielkopolska in the period of transformation of the political and economic system in Poland.     

Immobilization of Bacillus circulans β-galactosidase and its application in the synthesis of galacto-oligosaccharides under repeated-batch operation

A highly active and stable derivate of immobilized Bacillus circulans β-galactosidase was prepared for the synthesis of galacto-oligosaccharides (GOS) under repeated-batch operation. B. circulans β-galactosidase was immobilized on monofunctional glyoxyl agarose and three heterofunctional supports: amino-, carboxy-, and chelate-glyoxyl agarose. Glyoxyl agarose was the support with highest immobilization yield and stability being selected for the optimization of immobilization conditions and application in GOS synthesis. A central composite rotatable design was conducted to optimize contacted protein and immobilization time, using maximum catalytic potential as the objective function. Optimal conditions of immobilization were 28.9 mg/g and 36.4 h of contact, resulting in a biocatalyst with 595 IU/g and a half-life 89-fold higher than soluble enzyme. Immobilization process did not alter the synthetic capacity of β-galactosidase, obtaining the same GOS yield and product profile than the free enzyme. GOS yield and productivity remained unchanged along 10 repeated batches, with values of 39% (w/w) and 5.7 g GOS/g of biocatalyst·batch. Total product obtained after 10 batches of reaction was 56.5 g GOS/g of biocatalyst (1956 g GOS/g protein). Cumulative productivity in terms of mass of contacted protein was higher for the immobilized enzyme than for its soluble counterpart from the second batch of synthesis onwards.     

Transition of Shifting Cultivation and its Impact on People’s Livelihoods in the Miombo Woodlands of Northern Zambia and South-Western Tanzania

Shifting cultivation has long been a major livelihood for people in the miombo woodlands of southern, central and eastern Africa. However, increasing deforestation and forest degradation throughout the region are resulting in growing pressure on traditional shifting agricultural systems. Indeed, agricultural intensification and expansion itself is considered the primary cause of miombo deterioration, which is driven by both endogenous and exogenous variables operating at various scales. On the basis of data collected in the 1990s and 2010 from two villages in Northern Province, Zambia and two in the Rukwa Region, Tanzania, the paper will document the transition of shifting cultivation towards more intensive land use practices. It is argued that the main drivers influencing miombo degradation, and thereby the transition process of traditional shifting cultivation practices, have been a growing population, government policies, and an increasing commercialization/market integration. Questionnaires, focus group meetings, and in-depth interviews reveal that despite the breakdown of the traditional shifting cultivation practices, a general improvement of livelihoods has taken place. This has happened through adaptation and diversification in both agricultural practices and livelihood activities. However, it is also seen that because of the often rapidly changing external factors (market conditions and policies), life in the shifting cultivation communities involves a continual shift of emphasis among a variety of livelihood strategies.