Solubilization of membrane bound opiate receptor from rat brain

Sonication of rat brain membranes for 9 minutes solubilized 35% of their stereospecific opiate binding activity; a second 9 minute sonication of the insoluble residue released an additional 21% of the original binding. The opiate binding properties of the solubilized material were highly similar to those of membrane bound receptor by a number of criteria, including affinity, effect of sodium, and the IC₅₀ of unlabeled opiates in displacing ³H-etorphine binding. Moreover, storage of the solubilized receptor fraction for two weeks at ?20°C did not significantly change the receptor binding. Sonication thus appears to be a useful first step in purifying the opiate receptor.     

A calmodulin antagonist has no effect on the repair of X-ray-induced damage in a murine mammary carcinoma cell line

The effects of the calmodulin antagonist W13 were determined on potentially lethal damage repair, sublethal damage repair, and X-ray-induced DNA damage repair following X irradiation of 67 murine mammary carcinoma cells in the proliferative and quiescent states. Studies with W13 (20 micrograms/ml) on proliferating cells showed that the cells rounded up within 2 h but stayed attached to the dishes and there was a slight transient G2 block by 6 h. Also, the proportion of S-phase cells at 12 h was reduced to 65% of control with the concurrent [3H]thymidine incorporation reduced to 62% of control. There was no detectable effect from this pharmacological dose of W13 either on PLDR in proliferating cells at 400 and 800 rad or on quiescent cells at 200 and 400 rad. Likewise, there was no measurable effect on SLDR in either proliferating or quiescent cells at equally split doses of 800 and 600 rad, respectively. In addition, for control vs W13-treated proliferating cells, no difference was detected either in the induction of DNA damage by X irradiation or in the initial rate of repair (T 1/2 approximately equal to 7 min), as measured by the alkaline filter elution assay. In contrast to uv and bleomycin-induced damage, these data suggest that calmodulin may have no major role in either the molecular or cellular recovery from X-ray-induced damage in mammalian cells.     

DNA barcoding of freshwater fishes and the development of a quantitative qPCR assay for the species‐specific detection and quantification of fish larvae from plankton samples

The barcoding of mitochondrial cytochrome c oxidase subunit 1 (coI) gene was amplified and sequenced from 16 species of freshwater fishes found in Lake Wivenhoe (south‐eastern Queensland, Australia) to support monitoring of reservoir fish populations, ecosystem function and water health. In this study, 630–650 bp sequences of the coI barcoding gene from 100 specimens representing 15 genera, 13 families and two subclasses of fishes allowed 14 of the 16 species to be identified and differentiated. The mean ± s.e . Kimura 2 parameter divergence within and between species was 0·52 ± 0·10 and 23·8 ± 2·20% respectively, indicating that barcodes can be used to discriminate most of the fish species accurately. The two terapontids, Amniataba percoides and Leiopotherapon unicolor, however, shared coI DNA sequences and could not be differentiated using this gene. A barcoding database was established and a qPCR assay was developed using coI sequences to identify and quantify proportional abundances of fish species in ichthyoplankton samples from Lake Wivenhoe. These methods provide a viable alternative to the time‐consuming process of manually enumerating and identifying ichthyoplankton samples.     

Somatic embryogenesis, plant regeneration and cyanogenesis in Manihot glaziovii Muell. Arg. (ceara rubber)

 The report describes a system for somatic embryogenesis and direct plant regeneration from the embryos of Manihot glaziovii. Somatic embryos were obtained by culturing young leaf lobes (3–6 mm long) adjacent to the apex in Murashige and Skoog medium containing 18 μm 2,4-dichlorophenoxy acetic acid for 20 days and then transferring them to a maturation medium with 0.5 μm 6-benzylaminopurine. Secondary embryogenesis was induced from cotyledonary segments of somatic embryos by using the same protocol as that for primary embryogenesis. For regeneration, somatic embryos were cultured in medium supplemented with 10⁻⁴ m kinetin and 53.4% of them developed into plantlets. Linamarin and linamarase were not detected in calli or in somatic embryos. Linamarin content was found to be highest in leaves of regenerated plantlets, followed by stem and root tissues. Levels of linamarase activity were almost the same in leaves and stem tissues and very low in roots. Received: 19 April 1999 / Revision received: 11 August 1999 / Accepted: 17 August 1999     

Reproductive biology,length-weight relationship and diet of co-occurring butterfly rays,Gymnura poecilura and Gymnura zonura,in Malaysian waters

Recent IUCN assessments had resulted in up listing of the status of butterfly rays due to concerns of overfishing, but inadequate biological understanding of these rays prevents meaningful conservation and management measures. Therefore, this study was undertaken to address knowledge gaps in the reproductive biology and diet of longtail butterfly ray (Gymnura poecilura) and zone tail butterfly ray (Gymnura zonura) in Malaysian waters. From surveys of landing sites and fish markets from years 2017 to 2022, size (disc width, DW), weight and maturity were recorded, and stomachs were collected from 94 G. poecilura (N = 39 females and 55 males) and 20 G. zonura (N = 10 females and 10 males) specimens. The length-weight relationships were significantly different between sexes for G. poecilura. The size at maturity (DW50) was estimated to be 476.0 mm (females), 385.0 mm (males) for G. poecilura and 442.0 mm (combined) for G. zonura. The number of embryos ranged from 1 to 6, and the embryo size was between 73.90 to 130.44 mm DW. Dietary analysis of stomach contents revealed that fish prey was dominant in both G. poecilura [94.4% Index of Relative Importance (IRI)] and G. zonura (100% IRI). Ontogenetic shift was seen in G. poecilura that fed on more variety of prey items, including shrimps, squids and crabs with an increase in body size. Both species co-occur all along coastal Malaysia although G. zonura is rarely encountered from fisheries surveys along the Strait of Malacca. Given similar habitat associations and dietary habits, G. poecilura may be able to outcompete G. zonura across their shared habitat range. The validity of G. japonica and G. micrura records in Malaysia remains questionable and requires future investigation.     

Production of aposporous gametophytes and calli from Pteris vittata L. pinnae strips cultured in vitro

Murashige and Skoog's modified medium in 1% Difco Bacto-agar supplemented with sugar alcohols (sorbsitol, mannitol), growth regulators (1-naphthalenacetic acid, 2,4-dichlorophenoxyacetic acid, benzyladenine, kinetin) and sugars (fructose, glucose, sucrose) induced aposporous gametophytes from pinnae of Pteris vittata cultured in vitro at lower concentrations of all the mentioned components. Aposporous gametophytes and vegetative calli were produced at higher concentrations. The calli regenerated sporophytes when cultured on MS medium without growth regulators. The gametophytes grew vegetatively on MS medium but produced sporophytes when transferred into 0.1 strength MS medium. This is the first report of simultaneous production of calli and gametophytes from fern explants.     

Expression and function of asialo GM1 in alloreactive cytotoxic T lymphocytes

In the present study we examined asialo GM1 (AsGM1) expression and its function in alloreactive cytotoxic T lymphocytes (CTL). We consistently found that the cytotoxic activity of bulk culture-derived allo-CTL was susceptible to the treatment of anti-AsGM1 (alpha AsGM1) plus complement. To further determine whether the expression of AsGM1 was maintained in CTL, we examined cloned T cells. The expression of AsGM1 in the T cell clones was assessed by their susceptibility to lysis by alpha AsGM1 plus complement and the reduction or abrogation of their cytotoxic activity by this treatment. It was found that, with one exception, all Lyt-2+, Thy-1+ CTL clones were AsGM1+ (seven out of eight), independent of their class specificity (class I or class II). In contrast, all Thy-1+, L3T4+ CTL (2) or helper T cell (4) clones AsGM1-. These findings suggested that there was a close association between the expression of AsGM1 and the expression of Lyt-2. The cytotoxic reaction of the anti-class I MHC CTL clones that expressed AsGM1 was blocked by alpha AsGM1 or alpha Lyt-2 antibody. The Lyt-2+, AsGM1+ anti-class II MHC CTL clone-mediated lysis was inhibited by alpha AsGM1. Addition of AsGM1 in micelle form (AsGM1-M) alone also blocked the cytotoxic reactions. Addition of other structurally similar but antigenically different glycolipids or other non-AsGM1-containing liposome preparations did not affect CTL-mediated cytotoxicity. Furthermore, adding both alpha AsGM1 and AsGM1-M together at proper doses inhibited the blocking effect (deblocking) of either alone, and other structurally similar glycolipids did not inhibit the blocking. The deblocking was specific, since AsGM1-M did not affect the blocking by alpha Lyt-2. These findings indicate that not only is AsGM1 expressed in a majority of Lyt-2+ CTL clones, but it may also be involved in the CTL- target interaction to mediate lytic reaction.