Vegetative and reproductive development of Costa Rican weedy rice compared with commercial rice (Oryza sativa)

The variability in the chronology of the vegetative and reproductive development of weedy rice complex has been little studied. However, a field trial was established to study the timing of growth stages of sixteen weedy rice morphotypes and five rice varieties of Costa Rica. Weedy rice presented a wide range of variation for all descriptors among and within morphotypes. Weedy rice was taller than the rice varieties during vegetative phase and showed a growth increase of 14-23 cm every two weeks. Six morphotypes emerged earlier than commercial rice varieties, but no differences where found between samples for the time required for starting tillering. Early emergence of weedy rice morphotypes was not associated with early flowering, thus no correlation was detected between the vegetative and reproductive phases. All weedy rice morphotypes reached anthesis and maturity earlier than the rice varieties. Nevertheless, varieties Setesa-9 and CR-5272 overlapped anthesis with eleven morphotypes and variety CR-4338 overlapped flowering with eight weedy rice morphotypes. In contrast, none of the morphotypes overlapped anthesis with varieties CR-1821 and CR-1113. The results obtained showed the competitive capacity of weedy rice and provided valuable information about flowering overlap between weedy rice morphotypes and rice varieties which will be useful in the design of gene flow studies among them.

Ovule ontogeny of Tabebuia pulcherrima Sandwith (Bignoniaceae): megasporogenesis and integument development

The ovule of Tabebuia pulcherrima is anatropous, unitegmic and tenuinucellate. The nucellus shows a trizonate structural organization. The integument is initiated by periclinal divisions in the dermal layer (zone I), around the base of the archesporium. Subsequently, cells derived from the subdermal layer (zone II) start to push the dermal cells, so that they shift toward the micropylar region. The archesporial cell differentiates directly into the megaspore mother cell, undergoes meiosis, and originates a linear tetrad of megaspores. The mature embryo sac mother cell is elongated, possess a conspicuous central nucleus, and a characteristic bipolar vacuome with fibrous-granulated content. The inner cell layers of the integument differentiate into an amyloplast-rich endothelium. Patterns of callose deposition in the tetrad and selection of the functional megaspore, as well as the taxonomic value of some characters are discussed.

Primary and secondary development of Cyperus giganteus Vahl rhizome (Cyperaceae)

In Cyperus giganteus, like in other Monocotyledoneae, the protoderm, procambium, fundamental meristem and primary thickening meristem (PTM) are differentiated from the rhizome promeristem. The PTM produces the inner cortical parenchyma, endodermis, pericycle and amphivasal vascular bundles, which are formed by the procambium too. After the primary body differentiates, cellular divisions continue only in the pericycle, and originate an irregular vascular system with vessel elements shorter and more branched than those found in the primary growth. This change of activity in the pericycle defines a secondary growth, where the secondary thickening meristem (STM) is the pericycle itself.

Effect of abscisic acid on the mobilisation of galactomannan and embryo development of Sesbania virgata (Cav.) Pers. (Leguminosae - Faboideae)

Galactomannans (GM) are storage cell wall polysaccharides present in endospermic seeds of legumes. They are thought to be storage polymers, since it has been observed for a few species (among them Sesbania virgata) that they are completely broken down after germination and their products are transferred to the growing embryo. We examined the effect of 10-4 M abscisic acid (ABA) on the degradation of galactomannan in isolated endosperms and intact seeds of S. virgata. We found that after seed germination the initial embryo growth was retarded. Ultrastructural analysis showed that the embryo is completely surrounded by an endosperm which displays very thick galactomannan-containing cell walls. Although an inhibitory effect has been observed on the increase of fresh mass of the embryo, the effect of ABA on the dry mass was weaker and transitory (from 48 to 96 h). Endosperm dry mass and galactomannan degradation were significantly inhibited and the activity of alpha-galactosidase was strongly affected. The addition of ABA before and/or after the start of mobilisation in intact seeds or isolated endosperms, showed that whereas addition before mobilisation did not affect dry mass decrease in intact seeds, it was strongly affected in isolated endosperms. On the other hand, whereas it affected embryo fresh mass increase in intact seeds, but not in isolated embryos, no significant effect was observed on dry mass. These results suggest that ABA affects galactomannan degradation and by doing so, prevents water absorption by the embryo, rather than affect its dry mass. As ABA has been detected in the endosperm of seeds of S. virgata, it is proposed that it probably acts as a modulator of galactomannan mobilisation and consequently synchronises it with early growth of the embryo.

Megaspore germination and initial development of Regnellidium diphyllum Lindman (Pteridophyta, Marsileaceae) sporophytes in the presence of cadmium

Regnellidium diphyllum has its distribution restricted to Southern Brazil and adjoining localities in Uruguay and Argentina. Currently it is on the list of threatened species of Rio Grande do Sul. The conversion of wetlands into agricultural areas or soil contamination by the introduction of waste products and fertilizers may compromise the establishment and survival of this species. Among the pollutants are heavy metals, such as cadmium (Cd). Megaspores were germinated in liquid culture medium, with concentrations 0 (control), 0.39; 0.78; 1.56; 3.12; 6.25; 12.5; 25; 50 and 100 mg L-1 of Cd, starting from a standard solution of Titrisol® at 1000 mg L-1. The increase of Cd in the growth medium to 50 mg L-1 resulted in low germinability (58%), and no germination was observed on 100 mg L-1. In apomictical sporophytes, the growth of primary root and leaf was significantly reduced and no secondary leaf was formed at Cd concentrations of 12.5 and higher than this. The results indicated that R. diphyllum is tolerant to the presence of Cd up to considerably higher concentrations (0.78 mg L-1) than that normally found in unpolluted aquatic ecosystems (0.01 mg L-1), although the sensitivity to higher concentrations might endanger the establishment and permanence of this species in habitats exposed to contamination with this metal.

The board of directors as a part of family business governance – multilevel participation and board development

In this study, I examine the board of directors as a part of family business governance. Both boards and governance have increased their attractiveness as a research topic lately. Research on boards has concentrated mostly on the study of different board attributes, like composition, and the relationship of these attributes to the firm’s performance. Family business governance studies are criticized for ignoring the multifaceted needs of companies. More research observing the context and contingencies affecting the governance and board of directors is needed. The objective of this study is to clarify: 1) how the board participates in family business governance, and 2) how the board develops along with the firm’s and family’s development. The study is implemented as qualitative research, and the longitudinal process approach has been used as it provides the opportunity to examine development in context. Selection criteria for the two cases selected for this study are: active board of directors, at least one implemented succession, and interviewees available from two generations and from different positions in the firm. The data consists of interviews and secondary data, and it is collected from different data sources. The analysis was done selecting first some critical events from both cases to closer examination, and analysing them by using content analysis technique. Several conclusions were drawn basing on the findings. First, the family business board participates in the firm’s activities much more widely than it is customary to think. Second, the family business board is not a static part of the business, but it develops and it has to develop for different reasons. Third, ownership is not only the basis for the board’s activities or existence, but the relationship between the board and ownership is two-way. The board contributes to a large extent to the ownership decisions, and in this way to the management of ownership. Fourth, according to the cases, the board has many unrecognized possibilities to facilitate succession in family firms.

Biochemical profile of amniotic fluid for the assessment of fetal and renal development

Creatinine plays a key role in the function and maturation of fetal kidneys throughout pregnancy. It is important to identify other markers that may help in the diagnosis of renal dysfunction. Our aim was to determine the profile of and the correlation between biochemical markers to be used to assess renal function and maturation of the fetus in the amniotic fluid during pregnancy and to determine the distribution of normal values for creatinine, N-acetyl-ß-D-glucosaminidase (NAG), ß2-microglobulin, glucose, urea, sodium, potassium, phosphorus, calcium, uric acid, albumin, and osmolality in three gestational age groups. This was a cross-section study that assessed 115 samples of amniotic fluid during three different periods of pregnancy, i.e., 13 to 20, 27 to 34, and 36 to 42 weeks. Concentrations of creatinine, NAG, urea, potassium and uric acid increased during pregnancy (P<0.05). ß2-Microglobulin, glucose, sodium, phosphorus, calcium, and albumin concentration and osmolality decreased (P<0.05), whereas ß2-microglobulin, glucose and uric acid presented significant correlations with gestational age and creatinine, respectively (r>0.6, P<0.05). Urea, potassium and phosphorus showed mild correlations with both (r>0.5, P<0.05). NAG, sodium, albumin and osmolality did not show significant correlations (r<0.5, P<0.05). These tests confirmed the important role of creatinine in terms of correlation with gestational age. ß2-Microglobulin, glucose and uric acid were significant as markers of function and maturation of fetal kidneys, whereas NAG did not demonstrate a useful role for the assessment of renal maturation.

Short-lasting systemic and regional benefits of early crystalloid infusion after intravenous inoculation of dogs with live Escherichia coli

We investigated the systemic and regional hemodynamic effects of early crystalloid infusion in an experimental model of septic shock induced by intravenous inoculation with live Escherichia coli. Anesthetized dogs received an intravenous infusion of 1.2 x 10(10) cfu/kg live E. coli in 30 min. After 30 min of observation, they were randomized to controls (no fluids; N = 7), or fluid resuscitation with lactated Ringer's solution, 16 ml/kg (N = 7) or 32 ml/kg (N = 7) over 30 min and followed for 120 min. Cardiac index, portal blood flow, mean arterial pressure, systemic and regional oxygen-derived variables, blood lactate, and gastric PCO2 were assessed. Rapid and progressive cardiovascular deterioration with reduction in cardiac output, mean arterial pressure and portal blood flow (~50, ~25 and ~70%, respectively) was induced by the live bacteria challenge. Systemic and regional territories showed significant increases in oxygen extraction and in lactate levels. Significant increases in venous-arterial (~9.6 mmHg), portal-arterial (~12.1 mmHg) and gastric mucosal-arterial (~18.4 mmHg) PCO2 gradients were also observed. Early fluid replacement, especially with 32 ml/kg volumes of crystalloids, promoted only partial and transient benefits such as increases of ~76% in cardiac index, of ~50% in portal vein blood flow and decreases in venous-arterial, portal-arterial, gastric mucosal-arterial PCO2 gradients (7.2 ± 1.0, 7.2 ± 1.3 and 9.7 ± 2.5 mmHg, respectively). The fluid infusion promoted only modest and transient benefits, unable to restore the systemic and regional perfusional and metabolic changes in this hypodynamic septic shock model.

Systemic and regional hemodynamic effects of enalaprilat infusion in experimental normotensive sepsis

Angiotensin-converting enzyme inhibitors have been shown to improve splanchnic perfusion in distinct shock states. We hypothesized that enalaprilat potentiates the benefits of early fluid resuscitation in severe experimental sepsis, particularly in the splanchnic region. Anesthetized and mechanically ventilated mongrel dogs received an intravenous infusion of live Escherichia coli over a period of 30 min. Thereafter, two interventions were performed: fluid infusion (normal saline, 32 mL/kg over 30 min) and enalaprilat infusion (0.02 mg kg-1 min-1 for 60 min) in randomized groups. The following groups were studied: controls (fluid infusion, N = 4), E1 (enalaprilat infusion followed by fluid infusion, N = 5) and E2 (fluid infusion followed by enalaprilat infusion, N = 5). All animals were observed for a 120 min after bacterial infusion. Mean arterial pressure, cardiac output (CO), portal vein blood flow (PVBF), systemic and regional oxygen-derived variables, and lactate levels were measured. Rapid and progressive reductions in CO and PVBF were induced by the infusion of live bacteria, while minor changes were observed in mean arterial pressure. Systemic and regional territories showed a significant increase in oxygen extraction and lactate levels. Widening venous-arterial and portal-arterial pCO2 gradients were also detected. Fluid replacement promoted transient benefits in CO and PVBF. Enalaprilat after fluid resuscitation did not affect systemic or regional hemodynamic variables. We conclude that in this model of normotensive sepsis inhibition of angiotensin-converting enzyme did not interfere with the course of systemic or regional hemodynamic and oxygen-derived variables.

Inventive design and product development of a mechanical element

The thesis is dedicated to enhancement and development of a Mechanism in Company X in order to increase its key parameters and approve its workability. Current Mechanism model is described in details. The basis of various analysis, models and theories that are reflecting the working process of the Mechanism are included in the thesis. According to these three directions of enhancements are chosen: from mechanical, tribological and conceptual points of view. As the result the list of improvements is presented. The new models of Mechanism are built. The efficiency and lifetime value are obtained in accordance with corresponding estimations. The comparative analysis confirms the necessity of conducted changes. Recommendations for the Company X specialists are represented in the thesis. Proposals for deeper research are also suggested.

Informal learning and competence development during a management trainee program

The purpose of this research was to study how management trainee program participants experienced the program with respect to their learning and competence development. Additionally, the purpose was also to examine what the trainees learned and how the learning occurred. Furthermore, factors affecting learning in the workplace were examined. The theoretical framework of this research was formed utilizing individual competence and informal learning frameworks. Research was conducted as a single case study and data was gathered by thematic interviews. The results of this research indicate that the trainees experienced the program as a good method for learning the overall picture of the organization and its business. Regarding competence development, especially knowledge- and cognitive competence categories were developed during the program. The best learning outcomes were achieved through learning by doing, in co-operation with others, and learning from others. The results indicate that the planning of the program and its structure have a significant effect on learning. Furthermore, a sufficient level of challenge was experienced as being important for the quality of the learning as well.

Effect of conditioned medium of mesenchymal stem cells on the in vitro maturation and subsequent development of mouse oocyte

Mesenchymal stem cells (MSCs) secrete a variety of cytokines and growth factors in addition to self-renewal and multiple forms of differentiation. Some of these secreted bioactive factors could improve meiotic maturation in vitro and subsequent embryo developmental potential. The aim of the present study was to determine whether in vitro maturation (IVM) of mouse oocyte with or without cumulus cells could be improved by contact with conditioned medium (CM) of MSCs as well as the efficiency of CM to support follicular growth and oocyte maturation in the ovarian organ of mice cultured on soft agar. The developmental potential of matured oocyte was assessed by blastocyst formation after in vitro fertilization (IVF). Germinal vesicle stage oocytes with or without cumulus cells were subjected to IVM in either CM, Dulbecco's modified Eagle's medium (DMEM), α-minimum essential medium (α-MEM) or human tubal fluid (HTF). Approximately 120 oocytes were studied for each medium. CM produced a higher maturation rate (91.2%) than DMEM (54.7%), α-MEM (63.5%) and HTF (27.1%). Moreover, CM improved embryo development to blastocyst stage significantly more than DMEM and HTF (85 vs 7% and 41.7%, respectively) but there was no significant difference compared with α-MEM (85 vs 80.3%). The behavior of cortical granules of IVM oocytes cultured in CM revealed cytoplasmic maturation. Moreover, CM also supported preantral follicles growth well in organotypic culture on soft agar resulting in the maturation of 60% of them to developmentally competent oocytes. The production of estrogen progressively increased approximately 1-fold every other day during organ culture, while a dramatic 10-fold increase in progesterone was observed 17 h after human chorionic gonadotropin stimulus at the end of culture. Thus, CM is an effective medium for preantral follicle growth, oocyte maturation, and sequential embryo development.

Recombinant vaccines and the development of new vaccine strategies

Vaccines were initially developed on an empirical basis, relying mostly on attenuation or inactivation of pathogens. Advances in immunology, molecular biology, biochemistry, genomics, and proteomics have added new perspectives to the vaccinology field. The use of recombinant proteins allows the targeting of immune responses focused against few protective antigens. There are a variety of expression systems with different advantages, allowing the production of large quantities of proteins depending on the required characteristics. Live recombinant bacteria or viral vectors effectively stimulate the immune system as in natural infections and have intrinsic adjuvant properties. DNA vaccines, which consist of non-replicating plasmids, can induce strong long-term cellular immune responses. Prime-boost strategies combine different antigen delivery systems to broaden the immune response. In general, all of these strategies have shown advantages and disadvantages, and their use will depend on the knowledge of the mechanisms of infection of the target pathogen and of the immune response required for protection. In this review, we discuss some of the major breakthroughs that have been achieved using recombinant vaccine technologies, as well as new approaches and strategies for vaccine development, including potential shortcomings and risks.