Fusimotor innervation in the cat

The motor innervation of cat spindles was examined in hindlimb muscles using a variety of techniques employed in light and electron microscopy. Observations were made on teased, silver preparations of 267 spindles sampled from the peroneal, flexor hallucis longus, and soleus muscles, hereafter referred to as the PER/FHL/SOL series. The γ innervation. Trail endings are almost invariably present, and innervate both bag and chain muscle fibres. Trail fibres accounted for 64.6 to 74.8% of the total fusimotor supply to samples of spindle poles in the PER/FHL/SOL series, the mean number of fibres per pole varying from 2.7 to 5.0 in the different muscles, and the mean number of ramifications (areas of synaptic contact) per fibre being 3.7. By contrast, the p?innervation of a spindle pole generally consists of a single fibre supplying only one plate. In the above samples p(2) fibres accounted for 4.1 to 28.0% of the total fusimotor supply, and the mean number of fibres per pole varied from 0.3 to 1.2 in the different muscles. Ninety per cent of p(2) plates innervate bag fibres. The α innervation. The structure of p?plates as seen in both light and electron microscopy compares very closely with that of extrafusal plates. After nerve section p?plates degenerate at the same time as extrafusal plates, being the first of the three types of fusimotor ending to disappear. The frequency of the p?innervation is similar to that of the p?innervation. In the same samples of PER/FHL/SOL spindle poles as above p? fibres accounted for 6.0 to 28.8% of the total fusimotor supply, the mean number of fibres per pole varying from 0.25 to 2.1 in the different muscles. The majority of p? fibres enter a pole to terminate in one plate only. Seventy-five per cent of the plates innervate bag fibres. The three types of fusimotor ending are thus not selectively distributed to the two types of intrafusal muscle fibre. All three types of fusimotor fibre may branch within the spindle so as to innervate both bag and chain fibres. Bag fibres receive both types of plate ending as well as trail endings. Most chain fibres receive trail endings only; the rest receive either a p?or a p?plate innervation in addition, 25% of the p?and 10% of the p?innervation being distributed to chain fibres. The significance of this nonselective innervation is interpreted as indicating that the type of contraction elicited by stimulating a fusimotor fibre depends upon the type of ending initiating it rather than upon the type of muscle fibre executing it. Reasons are given for concluding that the dynamic response is controlled via the p?and p?plates, and that the static response is controlled by the trail endings. The participation of the α fibres in mammalian fusimotor innervation, previously regarded as a vestigial feature, proved to be widespread in the muscles studied and more prevalent in fast muscles (FHL, peroneus digiti quinti) than slow (soleus). A low frequency of p?innervation is offset by a high frequency of p?(as in peroneus longus), and vice versa (as in FHL). It is unlikely that collaterals from slow α fibres innervating type B muscle fibres are wholly responsible for the high frequency of the p?innervation in FHL, and it is suggested that collaterals may also be derived from fast α fibres innervating type C muscle fibres. The possibility of there being some motor fibres of α conduction velocity and with an exclusively fusimotor distribution is also taken into account.     

27-Nor-Δ4-dafachronic acid is a synthetic ligand of Caenorhabditis elegans DAF-12 receptor

27-Nor-Δ⁴-dafachronic acid was prepared in nine steps and 14% overall yield by two sequential 2-carbon homologations from 20β-carboxyaldehyde-4-pregnen-3-one. Its activity was evaluated in vivo, where it rescued the Mig phenotype of daf-9(rh50) Caenorhabditis elegans mutants and restored their normal resistance to oxidative stress. 27-Nor-Δ⁴-dafachronic acid was also able to directly bind and activate DAF-12 in a transactivation cell-based luciferase reporter assay, although it was less active than the corresponding 25R-and 25S dafachronic acids. The binding mode of the 27-Nor steroid was studied by molecular dynamics using a homology model of the CeDAF-12 receptor.     

Autophagy and mTOR pathways in mouse embryonic stem cell,lung cancer and somatic fibroblast cell lines

Embryonic developmental stages and regulations have always been one of the most intriguing aspects of science. Since the cancer stem cell discovery, striking for cancer development and recurrence, embryonic stem cells and control mechanisms, as well as cancer cells and cancer stem cell control mechanisms become important research materials. It is necessary to reveal the similarities and differences between somatic and cancer cells which are formed of embryonic stem cells divisions and determinations. For this purpose, mouse embryonic stem cells (mESCs), mouse skin fibroblast cells (MSFs) and mouse lung squamous cancer cells (SqLCCs) were grown in vitro and the differences between these three cell lines signalling regulations of mechanistic target of rapamycin (mTOR) and autophagic pathways were demonstrated by immunofluorescence and real-time polymerase chain reaction. Expressional differences were clearly shown between embryonic, cancer and somatic cells that mESCs displayed higher expressional level of Atg10, Hdac1 and Cln3 which are related with autophagic regulation and Hsp4, Prkca, Rhoa and ribosomal S6 genes related with mTOR activity. LC3 and mTOR protein levels were lower in mESCs than MSFs. Thus, the mechanisms of embryonic stem cell regulation results in the formation of somatic tissues whereas that these cells may be the causative agents of cancer in any deterioration.     

Methyl Jasmonate Increases the Tropane Alkaloid Scopolamine and Reduces Natural Herbivory in Brugmansia suaveolens: Is Scopolamine Responsible for Plant Resistance?

The tropane alkaloid (TA) scopolamine is suggested to protect Brugmansia suaveolens (Solanaceae) against herbivorous insects. To test this prediction in a natural environment, scopolamine was induced by methyl jasmonate (MJ) in potted plants which were left 10?days in the field. MJ-treated plants increased their scopolamine concentration in leaves and herbivory decreased. These findings suggest a cause?Ceffect relationship. However, experiments in laboratory showed that scopolamine affect differently the performance of the specialist larvae of the ithomiine butterfly Placidina euryanassa (C. Felder & R. Felder) and the generalist fall armyworm Spodoptera frugiperda (J. E. Smith): the specialist that sequester this TA from B. suaveolens leaves was not negatively affected, but the generalist was. Therefore, scopolamine probably acts only against insects that are not adapted to TAs. Other compounds that are MJ elicited may also play a role in plant resistance against herbivory by generalist and specialist insects, and deserve future investigations.     

Cyanotoxins in small artificial dams in Kenya utilised for cage fish farming – a threat to local people?

Nine small artificial dams located in different climatic regions of Kenya were studied. The local communities use the stored water for various purposes, such as irrigation, domestic use, watering of livestock and cage fish farming. Such intense use is commonly accompanied by eutrophication, including fast growth of cyanobacteria, which at times produce cyanotoxins threatening human and animal life. We studied the pelagic community, analysed abiotic variables and identified microcystins by means of high performance liquid chromatography and ELISA kits at monthly intervals over a period of one year. Mass spectrometry (MALDI-TOF MS) was used to identify structural variants of microcystins by their protonated masses (M + H). Three dams contained microcystins, with the highly toxic Microcystin-LR being identified as the most prominent substance. Cell content of the toxin varied from 7.2 to 686.7 fg cell^?1. Basic limnological variables that indicate the probability of toxin presence were also recorded. Non-parametric Mann–Whitney U-test revealed significant differences in soluble reactive phosphorous, nitrate-N, water depth, total hardness and post-Nauplii stages sampled between toxin-producing and non-toxin-producing dams. Although most of the samples did not contain high amounts of cyanobacteria, the cyanotoxin-problem was evident, suggesting the need for regular cyanotoxin monitoring programs.     

Structural basis of TRAPPIII‐mediated Rab1 activation

The GTPase Rab1 is a master regulator of the early secretory pathway and is critical for autophagy. Rab1 activation is controlled by its guanine nucleotide exchange factor, the multisubunit TRAPPIII complex. Here, we report the 3.7 Å cryo‐EM structure of the Saccharomyces cerevisiae TRAPPIII complex bound to its substrate Rab1/Ypt1. The structure reveals the binding site for the Rab1/Ypt1 hypervariable domain, leading to a model for how the complex interacts with membranes during the activation reaction. We determined that stable membrane binding by the TRAPPIII complex is required for robust activation of Rab1/Ypt1 in vitro and in vivo, and is mediated by a conserved amphipathic α‐helix within the regulatory Trs85 subunit. Our results show that the Trs85 subunit serves as a membrane anchor, via its amphipathic helix, for the entire TRAPPIII complex. These findings provide a structural understanding of Rab activation on organelle and vesicle membranes.     

Aflatoxicosis in rabbits: Effectiveness of Egyptian raw bentonite in prevention or diminution the detrimental effects of naturally aflatoxin contaminated diets

Thirty five females and 15 males of New Zealand White mature rabbits about 6 months of age, were assigned to 1–5 dietary treatments (7 does+3 bucks for each): uncontaminated control diet, naturally aflatoxin contaminated diet without or with 1,2 and 3% bentonite. Rabbit fed with the aflatoxin-diet had a decreased (P<0.01 or 0.05) physical semen characteristics of bucks and a reproductive performance traits of does. The values of conception rate (%), gestation length (days), litter size (n) and litter weights (g) at birth and viability (%) of litters of doe rabbits, fed with the aflatoxin-diet, recorded, respectively: 64.5; 31.0; 4.4; 275.0 and 57.1 versus 85.6; 30.3; 7.9; 508.0; and 100 for those fed with the uncontaminated diet. Addition of bentonite to the aflatoxin contaminated diet improved in general the physical semen characteristics of buck and reproductive performance traits of doe rabbits. The results of the study demonstrate that adding 1% of Egyptian raw bentonite to the naturally aflatoxin contaminated rabbit diets can provide an effective, cheap and safe practical technique for preventing the aflatoxicosis in mature rabbits.     

The ultrastructural and biosynthetic characteristics of steroidogenic cells in the gonad of Monopterus albus (Teleostei) during natural sex reversal

Summary The ultrastructural and biosynthetic characteristics of the steroid cells in the gonad of Monopterus albus have been studied. Ultrastructural features related to steroidogenesis have been identified in the interstitial Leydig cells, Sertoli cells, granulosa cells and thecal cells, and are especially abundant in the Leydig cells during the mid-intersexual phase. Steroidogenic ultrastructures in the Sertoli cells develop only during the maturation of the spermatogenic cysts, whereas in the granulosa and thecal cells, these features become obvious only during the maturation of the large oocytes. EM evidence also suggests a nutritive function for the Sertoli cells and the granulosa cells. Results of in vitro steroidogenic studies, using either testosterone or progesterone as a precursor, show a predominant conversion to androstenedione and 5-reduced compounds, and suggest a change in biosynthesis from 5-reduced products to androstenedione during sex reversal. 11-Ketotestosterone (11KT) has been identified, but not 11 -hydroxytestosterone. Production of 11 KT is high in the late intersexual and the male phases, but a lack of a marked variation in 11KT production between the early and the mid-intersexual phase suggests that this steroid is not a trigger for natural sex reversal in Monopterus.