Cell-cell interactions during the formation and reactivation of “nonculturable” mycobacteria

To date, the possible existence of “nonculturable” (NC) but potentially viable forms has been shown for some bacteria. NC mycobacteria have attracted particular interest due to the assumption that the latent form of tuberculosis is associated with the conversion of its causative agent, Mycobacterium tuberculosis, into the NC state. A number of approaches have been developed to obtain NC forms of mycobacteria, but the mechanisms of transition into or from this state have been insufficiently studied. This review considers cell-cell communications involved in the formation and reactivation of NC forms of the bacteria M. smegmatis and M. tuberculosis. Special attention has been paid to the secreted Rpf family proteins, which belong to peptidoglycan hydrolases and participate in the resuscitation of NC mycobacteria.     

The rôle of the tapetum in the formation of sporopollenin-containing structures during microsporogenesis in Pinus banksiana

Summary In the microsporangium of Pinus the outer layer of the peritapetal membrane and the pro-orbicular cores are not only formed in a similar manner, but are composed of apparently identical materials. Precursors for this lipoidal material are produced by the tapetal protoplasts, as are the precursors of sporopollenin. Production the precursors is sequential and appears to involve different cytoplasmic structures.The sporopollenin synthesised by the tapetum condenses upon the pro-orbicular cores, the peritapetal membrane, the exine initials and, on fragmentation of the tapetum, parts of the disintegrating cytoplasm. The evident unpolarised nature of the tapetal protoplasts, and the sequential nature of the synthesis of the lipoid and the sporopollenin by them, may point to orbicule formation in gymnosperms being a necessary by-product of the development of the peritapetal membrane.     

Role of the “thrombocytoids” in capsule formation in the dipteran Calliphora erythrocephala

Of the three hemocyte types present in the blood of Calliphora, only one participates in capsule formation around implanted cellophane. This hemocyte, the thrombocytoid, shows in the blood a tendency to dissociate into numerous small cytoplasmic fragments, comparable to the mammalian megakaryocyte. This tendency is dramatically increased during the process of encapsulation. Most of the intact thrombocytoids and the numerous fragments participating in capsule formation do not show any particular modifications in their cytoplasm during this process, which corresponds to a mere sequestration of the implant. Dense material, resulting from necrotic cell debris and hemolymph lipoproteins, is often observed between the cellophane and encapsulating thrombocytoids, which apparently participate in the resorption of this material.     

Lipid changes in blood serum and tissues of the Egyptian Cobra “Naja haje haje” during the hibernation cycle

• 1.Total lipids, free fatty acids, triglycerides, phospholipids and total cholesterol in blood serum, liver, brain, cardiac and skeletal muscles of Naja haje haje were determined during the different phases of the hibernation cycle.
• 2.A sharp decrease in the level of total lipids of blood serum and all tissues occurred during hibernation. Upon arousal, lipogenesis is commonly restored.
• 3.Elevated concentrations of serum free fatty acids predominated in pre-hibernation and hibernation periods, while the tissues recorded highly significant declines during hibernation.
• 4.Occurrence of marked decreases in triglycerides contents of serum and tissues except the cardiac muscles in the hibernation and arousal phases.
• 5.Sharp increases in the phospholipid contents of blood and the selected tissues were recorded during hibernation. The level declined in both liver and cardiac muscles in arousing animals.
• 6.Total cholesterol level was lowered in blood during hibernation. The cardiac muscles showed a highly significant decrease while liver, brain and skeletal muscles showed elevations in the same phase.

     

Supramolecular assemblies of histidinylated α-cyclodextrin in the presence of DNA scaffold during CDplexes formation

α-Cyclodextrin was transformed in a cationic unit after per substitution with histidine (His-α-CD) and lysine (Lys-α-CD) molecules on the primary face. His-α-CD and Lys-α-CD were used to form electrostatic complexes (CDplexes) with a plasmid DNA encoding luciferase gene, and the ability of CDplexes to transfect mammalian cells was examined using HEK293-T7 cells. The luciferase activity in cells transfected with His-α-CDplexes was 8-fold higher than that obtained Lys-α-CDplexes. When the transfection was carried out in the presence of chloroquine, the luciferase activity with His-α-CDplexes and Lys-α-CDplexes increased 6 and 25 times, respectively. The lower enhancement with His-α-CDplexes confirmed that histidine induced a proton sponge effect inside endosomes upon imidazole protonation, favoring DNA delivery in the cytosol. At the same time, we found that the condensation of DNA with His-α-CD was unexpectedly stronger than that obtained with the lysyl-α-CD counterpart. Moreover, it was as strong as that observed with high molecular weight polylysine. NMR (ROESY and DOSY) investigations in the absence of DNA showed that an inclusion complex is formed between the imidazole ring of histidine and the hydrophobic cavity of CD but no His-α-CD polymers can be formed by intermolecular interactions. These results suggest that intermolecular interactions between imidazole and His-α-CD cavity could be involved to form supramolecular assemblies in the presence of a DNA scaffold leading to DNA condensation into low diameter particles.     

Comments on the “Maintenance coefficient” changes during alcohol fermentation

Summary The concept of maintenance is discussed in terms of the biological meaning and the applicability of the maintenance coefficient, m, in bioengineering for optimization of yields in fermentation. A method of calculation is proposed for the evaluation of m in the course of fermentation in the case of a metabolite (e.g, ethanol). During alcoholic fermentation m is not constant and decreases with the growth rate.The phenomena involved in maintenance are numerous and complex and there is a semantic problem in its definition which can be generalized by the apparently non-finalized substrate consumption.Nomenclature a specific maintenance rate (defined by eq. (9)) - m maintenance coefficient - X cell mass concentration (as a dry weight) - S substrate concentration - P product concentration - r rate of reaction - r_x,r_s,r_p rate of reaction related to biomass, substrate and product - r_sm,r_sg,r_spi rate of reaction related only to the consumption by maintenance, growth and the synthesis of the ith product - r_xe maintenance rate defined by eq. (10) - q_s,q_Pi specific rate of substrate consumption and i^th product production - Y yield coefficient - Y^o, Y^o apparent yield coefficient related to the cell and i^th product - Y _xs ^xs , Y _Pis ^Pis maximum theoretical yield coefficient related to the cell and i^th - specific growth rate produce 420     

Analysis of carnitine, betaine, γ-butyrobetaine, and separate short-chain acylcarnitines in pigeon plasma, crop milk and tissues by HPLC coupled with UV-detection

Carnitine, betaine, -butyrobetaine and separate carnitine esters are determined in blood plasma, crop milk, liver, heart and breast muscle of pigeons (Columba livia domestica) by means of HPLC with photometric detection at 245 nm. The method can be generally applied for samples of animal origin.     

The formation of “compartment replicas” in the lymph nodes of athymic animals

Summary This communication describes a new anomaly that can affect the capsule of lymph nodes of athymic animals. Lymphocytes infiltrate a segment of the capsule above the variably atrophied peripheral cortex overlying the center of the deep-cortex unit of a node compartment. Lymphocytes thereafter form a capsular mass. The developing mass of lymphocytes is invaded by outgrowths of the node's subcapsular sinus while it fuses with the parenchyma of the related node compartment. Eventually, this new nodal element acquires structures resembling those of nodes and becomes a more or less exact replica of the original node compartment. Replicas stem from node compartments that are overchallenged by uncontrolled antigens. Aspects of the formation of replicas are explained by recent findings on events occurring in nodes of athymic animals and on the pattern of antigen distribution in the subcapsular sinus of a node. It is concluded that the formation of a compartment replica constitutes a mechanism allowing the organism to compensate somewhat for the partial atrophy or deficiency of a node compartment.Work funded by the Medical Research Council of Canada     

Variations of the lipid composition during the formation of cysts in the green alga Protosiphon botryoïdes

The formation of cysts in the alga Protosiphon botryoides, grown in a poor medium, is accompanied by important changes of the lipid composition of     

Secretion of gonadotrophins change during the luteal phase of the bovine oestrous cycle in the absence of corresponding changes in progesterone or 17β-oestradiol

The hypothesis in the present study was that changes in circulating luteinizing hormone (LH) and follicle stimulating hormone (FSH) would occur during the luteal phase of the oestrous cycle (Days 4–19; Day 0, day of behaviourial oestrus) that were not related to corresponding changes in concentrations of progesterone and 17β-oestradiol. The stage of the oestrous cycle of cows (n = 18) was synchronised to obtain cows that were on alternate days of the cycle. Blood samples were collected every other day at 15 min intervals for 12 h from all cows: Days 4, 6, 8, 10, 12, 14, 16, 18 (n = 9) and Days 5, 7, 9, 11, 13, 15, 17, 19 (n = 9). Concentrations of LH, FSH, 17β-oestradiol and progesterone were determined in these samples. Data were compared across days to determine when significant changes occurred in concentrations or patterns of secretion of the gonadotrophins and ovarian steroid hormones during the oestrous cycle. There were significant changes in mean concentrations of FSH in circulation between Days 6 and 12. The most striking changes in secretion of gonadotrophins that could not be explained by changes in gonadal steroids were the fluctuations in amplitude of LH pulses between Days 7 and 12. Amplitude of LH pulses increased between Days 7 and 11 and subsequently decreased between Days 11 and 12 of the oestrous cycle. Some changes in gonadotrophin secretion that occurred in the present study can be explained by fluctuations in concentrations of progesterone and 17β-oestradiol in circulation. Other changes cannot be explained by fluctuations in circulating concentrations of these steroids. We accept our hypothesis because the concomitant changes in mean concentration of FSH between Days 6 and 11 and amplitude of LH pulses between Days 7 and 12 of the bovine oestrous cycle cannot be explained by changes in circulating concentrations of progesterone and 17β-oestradiol.     

Restriction in the conformational flexibility of apoproteins in the presence of organic cosolvents: A consequence of the formation of “native-like conformation”

The influence of n-propanol on the overall α-helical conformation of β-globin, apocytochrome C, and the functional domain of streptococcal M49 protein (pepM49) and its consequence on the proteolysis of the respective proteins has been investigated. A significant amount of α-helical conformation is induced into these proteins atpH 6.0 and 4°C in the presence of relatively low concentrations of n-propanol. The induction of α-helical conformation into the proteins increased as a function of the propanol concentration, the maximum induction occurring around 30% n-propanol. In the case of α-globin, the fluorescence of its tryptophyl residues also increased as a function of n-propanol concentration, the midpoint of this transition being around 20% n-propanol. Furthermore, concomitant with the induction of helical conformation into these proteins, the proteolysis of their polypeptide chain by V8 protease also gets restricted. The α-helical conformation induced into α- and β-globin by n-propanol decreased as the temperature is raised from 4 to 24°C. In contrast, the α-helical conformation of both α- and β-chain (i.e., globin with noncovalently bound heme) did not exhibit such a sensitivity to this change in temperature. However, distinct differences exist between the n-propanol induced “α-helical conformation” of globins and the “α-helical conformation” of α- and β-chains. A cross-correlation of the n-propanol induced increase in the fluorescence of β-globin with the corresponding increase in the α-helical conformation of the polypeptide chain suggested that the fluorescence increase represents a structural change of the protein that is secondary to the induction of the α-helical conformation into the protein (i.e., an integration of the helical conformation induced to the segments of the polypeptide chain to influence the microenvironment of the tryptophyl residues). Presumably, the fluorescence increase is a consequence of the packing of the helical segments of globin to generate a “native-like structure.” The induction of α-helical conformation into these proteins in the presence of n-propanol and the consequent generation of “native-like conformation” is not unique to n-propanol. Trifluoroethanol, another helix-inducing organic solvent, also behaves in the same fashion as n-propanol. However, in contrast to the proteins described above, n-propanol could neither induce an α-helical conformation into performic acid oxidized RNAse-A nor restrict its proteolysis by proteases. Thus, the high sensitivity of apoproteins and the protein domains to assume α-helical conformation in the presence of low concentration of n-propanol with a concomitant restriction of the proteolytic susceptibility of their polypeptide chain appears to be unique to those proteins that exhibit high α-helical propensities. Apparently, this phenomenon of helix induction and the restriction of proteolysis reflects the formation of rudimentary tertiary interaction of the native protein and is unique to apoproteins or structural domains of α-helical proteins. Consistent with this concept, the induction of α-helical conformation into shorter polypeptide fragments of 30 residues, (e.g., α_1-30, which exists in an α-helical conformation in hemoglobin) is very low. Besides, this peptide exhibited neither the high sensitivity to the low concentrations of n-propanol seen with the apoproteins/protein domains nor the resistance toward proteolysis. The results suggest that the organic cosolvent induced decrease in the conformational flexibility of the apoprotein, and the consequent restriction of their proteolytic cleavage provides an opportunity to develop new strategies for protease catalyzed segment condensation reactions.     

Seasonal changes in zooplankton abundance in the lower Rhine during 1987–1991

Zooplankton in the River Rhine was surveyed for five years at the Dutch sampling stations, Lobith (German/Dutch border) and Maassluis (at the point of discharge of the river into the North Sea). The zooplankton abundance showed an apparent seasonal pattern at both stations, characterized by low densities during the winter period, and higher densities during the summer period, with a spring peak. Zooplankton was dominated by rotifers at both stations, although during the winter periods the contribution of copepods was considerable. The rotifers were dominated byBrachionus angularis, B. calyciflorus, Keratella cochlearis andK. quadrata; the copepods by cyclopoid nauplii; the cladocerans by small-sized species mainly belonging toBosmina. At Maassluis the relative contribution of copepods was higher than at Lobith. Furthermore, the zooplankton at Maassluis included the speciesEurytemora affinis, characteristic for estuarine conditions. In spring, the rotifer density and water temperature and rotifer density and chlorophylla concentration were positively correlated. Furthermore, both rotifer density and chlorophylla were inversely correlated with discharge. The possible role of environmental factors (water temperature, chlorophyll content, discharge and biotic factors) controlling the river zooplankton dynamics is indicated.     

Does the nucleus raphes participate in the regulation of resting and stress-induced hypothalamic-pituitary-adrenocortical activity in the pigeon?

Extensive multiple electrolytic lesions were placed into the nucleus raphes of the brain stem in the pigeon. Diurnal pituitary-adrenocortical rhythmicity appeared not to be altered and basal plasma corticosterone level remained quite normal in raphe lesioned birds. Electrical stimulations through permanently implanted electrode were delivered in various central nervous structures in unanaesthetized, freely moving pigeons. Stimulations of nucleus raphes and of various parts of formatio reticularis led to a significant rise in plasma corticosterone within 16 to 19 min after the beginning of the stimulating session. Then, plasma B came again to initial level within 15 minutes. Stimulations of the corticotropic area of the hypothalamus (n. posterior medialis hypothalami) and of archistriatum dorsalis induced an early plasma corticosterone increase occurring immediately after the stimulating burst (10 min). Stimulating the n. septum medialis also had an immediate, but reverse (decrease) effect on plasma corticosterone level. Stress-induced pituitary-adrenal cortical activation exhibited a temporal pattern quite similar to that observed after brain stem (n. raphes or formatio reticularis) stimulation. It is suggested that these various limbic and brain stem areas might be involved in some "limbic system-midbrain circuit" with two components : The forebrain component might be involved in the regulation and diurnal modulation of basal hypothalamic-pituitary-adrenocortical function, the brain-stem component interferring with stress-induced responses.     

An emergy evaluation of the sustainability of Chinese crop production system during 2000–2010

Crop production systems are the basis of human survival and development because they can produce grain and industrial raw materials. As one of the largest agricultural countries in the world, the sustainability of China's crop production system is being concerned widely with its economic development and increasing population. This study adopted emergy analysis to explore the comprehensive performance of this system. A set of emergy based indicator system was used to investigate its economic benefit, environmental pressure and sustainability from 2000 to 2010. The study results show that the purchased nonrenewable input makes the largest contribution to the total input (average value 60.73% of the total input), which mainly derived from agricultural mechanic equipments and chemical fertilizer; on the average, beans has the largest share (20.20%) to the total emergy output, next from rape seed (18.36%), then from peanuts (15.85%), fruits (15.74%), wheat (8.26%), rice (8.07%), corn (7.66%) and cotton (4.60%) accordingly, and the other four categories crops just have a contribution of 1.28%; the production efficiency of China's crop production system has been raised by 11.54% with decrease of the indicator unit emergy value of product (UEVP) from 1.82E09 sej/g to 1.61E09 sej/g, the dependence of this system on economic market has increased by 24.92% with growth of the indicator EIR from 6.22 to 7.77, its economic benefit has been reduced by 0.59% with decline of the indicator EYR from 1.69 to 1.68, and its environmental loading has raised by 57.89% with growth of the indicator ELR from 1.33 to 2.10; the sustainability of China's crop production system is reduced by 37.01% with decrease of the index ESI from 1.27 to 0.80, during this study period. Based on these study results, the following measures should be emphasized in future, including raising the efficiency of purchased non-renewable resources (especially agricultural mechanical equipments and chemical fertilizer), using other methods of cultivation inherently more sustainable (e.g. replacing chemical fertilizer with organic fertilizer, recycling organic wastes, biological control of agricultural pests, use of local renewable energy, and more), strengthening supervision of the related industrial processes and further promoting agricultural environmental protection.     

Physical changes of β-sitosterol crystals in oily suspensions during heating

The aim of this research was to describe the thermal behavior of β-sitosterol crystals in oil-suspensions with a focus on the role of water during heating. The suspensions were prepared by recrystallization in order to achieve a microcrystalline particle size. The structural changes together with the mechanical properties of the suspensions during heating were studied by using variable temperature X-ray powder diffractometry (VT-XRPD), differential scanning calorimetry (DSC), and dynamic mechanical analysis (DMA). Hydrated β-sitosterol crystals in an oil-suspension, dehydrated, despite the composition of the suspensions, at low temperatures. At high β-sitosterol concentration, the monohydrate crystal form changed partially to a hemihydrated form, and when only a small amount of water was initially incorporated, the hemihydrate crystal form dehydrated to a mostly anhydrate crystal form. The released water, which was immiscible in the surrounding oil, caused the recrystallization of hydrated β-sitosterol during cooling. This procedure indicated a reversible dehydration process. Structural and thermal analysis of β-sitosterol crystals in suspensions, together with mechanical analysis made it possible to understand various physical changes during heating. Published: October 19, 2005     

Consumption of transgenic cows’ milk containing human lactoferrin results in beneficial changes in the gastrointestinal tract and systemic health of young pigs

Lactoferrin is an antimicrobial and immunomodulatory protein that is produced in high quantities in human milk and aids in the gastrointestinal (GI) maturation of infants. Beneficial health effects have been observed when supplementing human and animal diets with lactoferrin. A herd of genetically engineered cattle that secrete recombinant human lactoferrin in their milk (rhLF-milk) have been generated which provide an efficient production system and ideal medium for rhLF consumption. The effects of consumption of rhLF-milk were tested on young pigs as an animal model for the GI tract of children. When comparing rhLF-milk fed pigs to non-transgenic milk fed pigs (control), we observed that rhLF-milk fed pigs had beneficial changes in circulating leukocyte populations. There was a significant decrease in neutrophils (p = 0.0036) and increase in lymphocytes (p = 0.0017), leading to a decreased neutrophil to lymphocyte ratio (NLR) (p = 0.0153), which is an indicator of decreased systemic inflammation. We also observed changes in intestinal villi architecture. In the duodenum, rhLF-milk fed pigs tended to have taller villi (p = 0.0914) with significantly deeper crypts (p < 0.0001). In the ileum, pigs consuming rhLF-milk had villi that were significantly taller (p = 0.0002), with deeper crypts (p < 0.0001), and a thinner lamina propria (p = 0.0056). We observed no differences in cytokine expression between rhLF-milk and control-milk fed pigs, indicating that consumption of rhLF-milk did not change cytokine signaling in the intestines. Overall favorable changes in systemic health and GI villi architecture were observed; indicating that consumption of rhLF-milk has the potential to induce positive changes in the GI tract.