Morphology and larval development of the parasitoid fly Exorista larvarum (L.)

This study reveals the morphology of immature E. larvarum and the changes during its development and offers detailed investigations on the larval body structures from the histological point of view

Корпоративний менеджмент: структуризація капіталу та податкові щити

У практиці корпоративного управління оподатковуваним прибутком застосовуються методи структуризації капіталу та податкових щитів з метою зменшення податкових платежів, максимізації ринкової та акціонерної вартості компаній, незалежно від котирування їх акцій на фондовій біржі. У рамках даного дослідження проаналізовано взаємозв’язок між податковим щитом, структурою капіталу та ефективністю управління прибутками. Визначено ефективну модель структуризації капіталу для оптимізації податкових та неподаткових надходжень у досліджуваних країнах. Емпіричне дослідження проведено на основі панельних даних, сформованих для вибірки з більш ніж 5000 нефінансових компаній у Словаччині та Чехії за 2014-2017 роки. Практичну реалізацію дослідження здійснено з використання трьох варіантів коефіцієнта кредитного важеля (загальний, короткостроковий та довгостроковий). У роботі досліджено податкові щити за рівнем фактичної ставки податку, за умови маніпулювання прибутками за дискреційними нарахуваннями на основі аналізу корпоративних на національних показників (ВВП та інфляція). За результатами негативної залежності між рівнем прибутку та кредитним важелем, встановлено, що компанії слідують модифікованій теорії ієрархії для країн, з перехідною економікою. Прибуткові компанії Чехії та Словаччини використовують податкові та неподаткові пільги в незначній мірі. При цьому широке застосування отримали методи маніпулювання, що не пов’язані із податками на прибуток (управління прибутками). Як правило, компанії, які мають заборгованість, можуть підвищувати бухгалтерський прибуток для полегшення боргової ситуації. При цьому маніпуляції з бухгалтерським прибутком негативно впливають на короткостроковий борг, оскільки значна заборгованість посилює вимоги до якості бухгалтерського прибутку позичальника. Авторами наголошено, що розроблений підхід може бути використаним при прийнятті рішень усіма зацікавленими сторонами (менеджерами, власниками акцій та власниками боргів/кредиторами) компанії.Corporate management affects taxable profit through capital structure and tax shields. The reason for these manipulations is primarily to minimize corporate taxes and maximize the corporate market value and shareholder value of both listed and unlisted companies. The study explores the relationship between the tax shield and the capital structure and the influence of earnings management on it. Secondly, it evaluates which of the known models of capital structure best suits the conditions of the analyzed countries concerning tax and non-tax profit optimization. These effects were examined on panel data of more than 5,000 non-financial Slovak and Czech companies from 2014 - 2017. Three variants of the leverage ratio (total short-term and long-term) were used as proxies for the capital structure. Tax shields were examined at the level of the effective tax rate, profit manipulation at the level of discretionary accruals by checking firm-level factors and country-level factors (GDP and inflation). The negative dependence of profitability and leverage indicated that companies follow the conclusions of the Pecking order theory modified for emerging economies. Slovak and Czech profitable companies use tax interest and non-interest benefits only to a small extent since it is being replaced by non-tax profit manipulation (earnings management). Instead, indebted businesses tend to increase accounting profits to obtain cheaper long-term debt. Moreover, accounting manipulations have a negative impact on short-term debt as a high degree of indebtedness enhances debt holders' demands for quality accounting profit. The authors proved that conclusions could be improve theoretical knowledge of the capital structure in Czech and Slovak companies. Besides, developed approach could be useful in the decisionmaking of all stakeholders (managers, equity holders, and debt holders/creditors)

LARVAL MORPHOLOGY AND ANATOMY OF THE PARASITOID EXORISTA LARVARUM (DIPTERA: TACHINIDAE), WITH AN EMPHASIS ON CEPHALOPHARYNGEAL SKELETON AND DIGESTIVE TRACT

The endogenous development of the tachinid gregarious larval parasitoid Exorista larvarum (L.) (Diptera: Tachinidae) has been analyzed in the last larval instar of a factitious host, the wax moth Galleria mellonella (L.) (Lepidoptera: Pyralidae), using histological techniques and scanning electron microscopy. This study has focused on the parasitoid internal body structures and their changes during the larval development. The first and second instar are enveloped by a host-derived hemocyte capsule attached to the respiratory funnel via a prominent anal hook located between 2 anal lobes. The third instar abandons the respiratory funnel and migrates free in the body cavity of the already dead host. Emphasis is given to the prominent cephalopharyngeal skeleton, highlighting the morphological aspects of its sclerotized as well as non-sclerotized components. In addition to the cephalopharyngeal skeleton, the anterior third of the larval parasitoid body is occupied by large salivary glands, massive proventriculus, and cerebral ganglia. The extensive digestive tract, which occupies the major part of the body, is differentiated into well-marked individual parts. The abdomen is predominantly filled with the extremely long mesenteron that increases in size during the larval development. The whole body is covered by an apparently thin integument, with strong spines that are especially numerous in the anterior and posterior body parts

Aplikace elektrofyzikalni metody pri urcovani kvality prirodni slozky prostredi - drevin.

Each type of plant demonstrates its own phyto-electric (P-E) currents. The value of the P-E currents increases with the tree's age. Plants annually maintain a periodical course with maximum values during summer and minimum values in winter. The highest P-E activity is always concentrated in the trunk cambia layers. The comparison of the health state and the values of P-E currents have brought new dimensions in the classification of tree vitality. Healthy trees reach the highest P-E currents. The worst is the state of a tree the quicker is the rate of deterioration. The entire changing process of a tree's health state can be precisely monitored. Assessing a tree's health state with visual methods is not precise. Changes of the mesh electric conduction are related to changes in water capacity and electrolytes concentration. Electric conduction of the mesh seldom changes at short intervals. Measuring electric impedance or electric conduction of a tree mesh in cambial zones can be used to determine cambial activity, which correlates to tree vitality. During the dormant phase vitality decreases and electric resistence in the mesh increases. The given electric characteristics are influenced by certain physiological processes such as the metabolism and growth intensity. However, these factors are co-related to the tree's vitality. Measuring electronic resistance of the mesh in the cambial zone has proved that its changes are co-related to season changes. The lower resistance values correlates to higher relative vitality of the tree. One can name it electric impedance or electric conduction of tree tree mesh. Both mentioned terms have their own physical unitis which can be compared to tree vitality and then mathematically calculated.Available from STL Prague, CZ / NTK - National Technical LibrarySIGLECZCzech Republi

Penetration and encapsulation of the larval endoparasitoid Exorista larvarum (Diptera: Tachinidae) in the factitious host Galleria mellonella (Lepidoptera: Pyralidae)

The tachinid fly Exorista larvarum (L.) (Diptera: Tachinidae) is a polyphagous larval endoparasitoid that deposits its eggs on the host exoskeleton of lepidopteran and tenthredinid larvae. The attachment of larval E. larvarum and the formation of the respiratory funnel were studied during infestation in the last larval instar of the wax moth, Galleria mellonella (L.) (Lepidoptera: Pyralidae). The tachinid larvae burrow through the host integument after hatching, using their robust cephalopharyngeal skeleton, leaving a dark spot at the point of their penetration as a result of host cuticle melanization. Endoparasitoid penetration induces the host cellular defence, resulting in the formation of a haemocyte capsule consisting of multi-cellular sheaths. This enveloping capsule later undergoes melanization, which is mostly obvious towards the posterior part of the endoparasitoid. The endoparasitoid uses the host encapsulation response to build a respiratory funnel from the modified host integument, leading to the host surface. The encapsulated larva remains attached to the respiratory funnel via an anal hook and cuticular spines until fully developed. Additional immunohistochemical analyses were used to study host\u2013parasitoid interactions. Indirect immunofluorescence showed no labelling of potential tachinid antigens and confirmed no effect on the surrounding host tissues. A simulated parasitization with coated polybead microspheres revealed the mortal impact of tachinid antigens to the host. Hosts injected with antigen-coated polybeads died as a consequence of an acute and extensive immunological response to the tachinid antigens and not due to the trauma caused by foreign objects inside their body.

Novel Discoveries in the Male Accessory Secretions of the Tsetse fly (A transcriptomic/proteomic analysis)

Tsetse flies are the sole vectors of the human and animal forms of African Trypanosomiasis, neglected diseases that affect the health and development of marginalized populations in sub-Saharan Africa. Vector population control is one of the primary methods to prevent trypanosomiasis transmission. However, little is known about the reproductive biology of tsetse flies. A particularly important aspect of tsetse reproductive biology, male seminal secretions, remains unstudied. Based upon the knowledge derived from other insects such as Drosophila and various mosquito species, the proteins contained within these secretions play an important roles in regulating sperm storage, sperm motility, sperm competition, female sexual receptivity, egg production, ovulation, reproductive tract morphology, feeding behavior and other aspects of fly biology. To establish a foothold on this aspect of tsetse reproductive biology, we undertook a project to sequence the transcriptome of the male accessory tissue in tsetse and to sequence the proteome of the male seminal secretions found within the female after mating. Material for transcriptomic analysis was derived from dissected adult male reproductive tracts at different time points. Samples were collected from teneral, 3 day old (reproductively mature), and 6-8 hours post mating male flies. Male reproductive tracts were dissected into two fractions, testes and accessory glands. RNA isolated from these samples was used to construct 6 illumina libraries which were sequenced using paired end sequencing technology. To complement the transcriptomes, samples of male produced spermatophores were collected for proteomic analysis from the uterus of newly mated female flies. Protein samples were analyzed by LC-MS/MS. Male accessory and testes illumina sequencing data was analyzed to identify the most abundant transcripts within each library, compared between libraries to identify temporal and tissue specific differential expression patterns and compared with transcriptome data from adult female flies to identify male specific transcripts. The results of these analyses were then compared with the proteomic data to confirm transcriptomic predictions of secreted accessory proteins and identify additional unpredicted proteins. Analysis of these data sets resulted in the identification of a novel set of male accessory genes/proteins. Our initial analysis has identified a total of 25 putative accessory gland proteins via cross referencing our tissue specific transcriptome and the spermatophore proteome. Of these proteins, only one of the predicted genes (a serine protease inhibitor from the BPTI/Kunitz family) is orthologus to an accessory protein identified within Drosophila. Many proteins identified are tsetse specific and novel. Three of these novel proteins are the most abundant proteins in the spermatophore. These three proteins form a novel tsetse specific gene family that appears to have arisen through tandem gene duplication events. Further functional analysis will be required to identify the role that these novel proteins play in tsetse reproductive physiology. However, while many of the proteins we have identified are not true orthologs to other characterized accessory proteins, their function appears to have remained orthologus to those of accessory proteins from other Dipteran species. These functions include serine protease inhibitors, odorant binding proteins, antioxidants, immune proteins, glycoproteins, endocuticle proteins and sperm binding proteins