The microbial production of 3aα-H-4α- (3′-propionic acid)-5α-hydroxy-7aβ-methylhexahydro-indan-1-one-δ-lactone from cholesterol

Summary A mutant strain of Rhodococcus australis CSIR-236.457 which accumulates 3a-H-4-(3-propionic acid)-5-hydroxy-7a-methylhexahydro-indan-1-one--lactone from cholesterol, stigmasterol and -sitosterol was studied. The product is produced in a 60% molar yield in a dilute black strap molasses medium containing 6–12g/l cholesterol after a 72 hour fermentation period.     

The effect of experimental induced hypocalcaemia on uterine activity in the sow during parturition and post-partum

Uterine activity was measured by monitoring intrauterine pressure changes using ballon-tipped catheters placed in the lumen. An infusion rate of Na(2)EDTA of 35 mg/Kg/h gave a chelation rate equivalent to the rate of calcium mobilisation, and when infused at a level greater than this, resulted in a reduction in plasma calcium concentrations and a concomitant reduction in uterine activity. In three of the four sows infused intrapartum, there was complete cessation of uterine activity; however, plasma calcium concentrations of less than 6 mg 100 ml resulted in a reduction in uterine activity at this stage of parturition. The uterus of the sow post-partum appeared to be more sensitive to the effects of hypocalcaemia with reduced uterine activity when plasma calcium concentrations fell below 8.2 mg 100 ml and complete cessation of activity between 6 and 7 mg 100 ml . Although there was evidence of a delay in the expulsion of piglets in the hypocalcaemic sows, there was no evidence of an increased number of stillborn piglets compared with the two control sows.     

Exudate-feeding byCallithrix jacchus penicillata in semideciduous woodland (Cerradão) in central Brazil

We report the exudate feeding behavior of two groups of marmosets (Callithrix jacchus penicillata) living permanently in Cerradão, a common woodland formation of Central Brazil. Cerradão is an open canopy formation and marmosets must occasionally descend to the ground in order to move from tree to tree. Even in atypical habitat, exudate eating is the predominant foraging activity. Marmosets are engaged in exudate collection over 70% of the total time spent feeding. They were observed gnawing on seven species of trees, and consumed exudates from four of these species. We compared the degree of utilization of the exudate sources, and examined a number of different characteristics of the exudates. Morphological adaptations that allow for the exploitation of the “exudate-eater niche” may be an important component of the adaptability ofCallithrix marmosets.     

The larval midgut of the cassava hornworm (Erinnyis ello)

Summary Columnar cells of the larval midgut of the cassava hornworm, Erinnyis ello, display microvilli with vesicles pinching off from their tips (anterior and middle midgut) or with a large number of double membrane spheres budding along their length (posterior midgut). Basal infoldings in columnar cells occur in a parallel array with many openings to the underlying space (posterior midgut) or are less organized with few openings (anterior and middle midgut). Goblet cells have a cavity, which is formed by invagination of the apical membrane and which occupies most of the cell (anterior and middle midgut) or only its upper part (posterior midgut). The infolded apical membrane shows modified microvilli, which sometimes (posterior midgut) or always (anterior and middle midgut) contain mitochondria. The cytoplasmic side of the membrane of the microvilli that contain mitochondria are studded with small particles. The results suggest that the anterior and middle region of the midgut absorbs water, whereas the posterior region secretes it. This results in a countercurrent flux of fluid, which is responsible for the enzyme recovery from undigested food before it is expelled. Intermediary and final digestion of food probably occur in the columnar cells under the action of plasma membrane-bound and glycocalix-associated enzymes.     

Aspects of the biology of the euryhaline Asian cichlid,Etroplus suratensis

Synopsis Aspects of the biology of the euryhaline Asian cichlid Etroplus suratensis in a coastal lagoon of Sri Lanka were studied for a period of 15 months. Comparisons are made from the catches from the fishery of manmade, inland freshwater reservoirs. Changes in the stock structure in the sublittoral region of the lagoon indicate that recruitment takes place twice a year, during the high rainfall/low salinity periods. The feeding habits of E. suratensis were different in the two habitats. In the lagoon it fed mainly on molluscs and in the freshwater reservoirs on macrophytes. Feeding chronology based on diurnal surveys indicate that it feeds mainly during the daylight hours. The dentition of E. suratensis is adapted for both tearing and crushing (pharyngeal teeth). Distinct differences in the mean relative intestinal length between populations from the coastal lagoon and inland reservoirs were evident and these differences are correlated to their respective feeding habits. Diurnal changes in feeding activity are associated with changes in the stomach pH. The egg-diameter distribution of mature fish indicate that E. suratensis is a single spawner, that it sheds its mature eggs all at once. It is inferred that E. suratensis breeds twice a year but that an individual female is capable of spawning only once a year.     

A model of the spatial-temporal characteristics of the alpha rhythm

A linear spatially distributed model of a chain of neurons and interneurons was investigated in relation to the generation of propagated alpha rhythmic activity. It was assumed that the elements of the chain were interconnected by means of recurrent collaterals and inhibitory fibres in such a way that the connectivity functions were assumed to be homogeneous and their strength was an exponentially decreasing function of distance. It was found that such a neuronal chain shows propagation properties for frequencies in the alpha band. The results obtained with the model are in agreement with the phase velocities encountered experimentally. In this way, it was possible to estimate the length of the neural fibres responsible for the phenomenon of propagated activity. The estimates obtained are in good agreement with recent quantitative neuroanatomical data on the circuitry of the neocortex.     

Pelvic visceral arteries of rabbits (Oryctolagus cuniculus)]

40 pelvic preparations of rabbits (oryctolagus cuniculus) were bilaterally studied by dissection under the stereomicroscope and angiography. The arterial pattern of the pelvis, i.e. origin and branching of the umbilical, urogenital and internal pudendal arteries (visceral branches), is described. The main characteristics observed are as follows: (1) The umbilical artery is permeable in adults and gives origin to the cranial vesical artery and a caudal branch that irrigates the pelvic urogenital organs and, eventually, the rectum, with six patterns of branching in both sexes. (2) Usually, the urogenital artery is the continuation of the visceral branch of the internal iliac artery. In 1 animal, unilaterally, it arises from the median sacral artery. In 12 animals (6 bilaterally and 6 unilaterally) the urogenital artery is absent. When present, it forms two branches, a cranial and a caudal one, that irrigate of the urogenital organs in both sexes. (3) The internal pudendal artery is the direct continuation of the internal iliac artery and gives to rise to some visceral branches that irrigate the penis, bulbourethral gland and rectum (with six patterns of branching) in males, and the vagina, clitoris and rectum (with three patterns of branching) in females.     

Aliphatic hydrocarbons as biological markers in 250-million-year-old rock salt deposits near Kassel,West Germany

Organic matter sedimented within salt deposits from the Carboniferous Perm epoch has been investigated for hydrocarbons by gas-liquid-chromatography, mass spectrometry, and spectropolarimetry. Main constituents were made of aliphatic and olefinic hydrocarbons which retained a considerable part of their optical activity thus resisting complete racemization over 250 mio years.     

Structural changes in thin filaments of crab striated muscle.

Low angle X-ray diffraction patterns were recorded from crab leg muscle in living resting state and in rigor (glycerol-extracted). Both resting and rigor patterns showed a series of layer-lines arising from a helical arrangement of actin subunits in the thin filaments. In the resting state, the crossover repeat of the long-pitch actin helices was 36.6 nm, and the symmetry of the genetic actin helix was an intermediate between $\text{26}\text{12}$ and $\text{28}\text{13}$. When the muscle went into rigor, the crossover repeat changed to 38.3 nm and the helical symmetry to $\text{28}\text{13}$.In the living resting pattern, six other reflections were observed on the meridian and in the near-meridional region. These were indexed as orders of 2 × 38.2 nm and could be assigned to troponin molecules; the spacings and the intensity distributions of these reflections could be explained by the model proposed by Ohtsuki (1974) for the arrangement of troponin molecules in the thin filaments.The muscle in rigor gave meridional and near-meridional reflections at orders of 2 × 38.3 nm. These were identified as the same series of reflections as was assigned to troponin in the living resting pattern, but were more intense and could be seen up to higher orders. We consider that the myosin heads attached to the thin filament at regular intervals along its axis also contribute to these reflections in the rigor pattern.