Penicillin-binding proteins of protoplast and sporoplast membranes of Streptomyces griseus strains

Membrane-bound penicillin-binding proteins (PBPs) of two Streptomyces griseus strains that sporulate well in liquid and solid medium have been investigated during the course of their life-cycle. The PBP patterns were analyzed by sodium dodecylsulphate polyacrylamide-gel electrophoresis and fluorography. One strain (No. 45 H) has only a single band (mol wt: 27,000) in early log phase, and two additional PBPs of higher mol wt (69,000 and 80,000) in the late log phase. The other strain (No. 2682) possessed two bands with mol wts 27,000 and 38,000 which did not change during its vegetative phase. In strain No. 2682, a new PBP with a mol wt of 58,000 appeared in spore membranes while one of those (mol wt 38,000) present in mycelial membranes disappeared. Our results suggest that appearance of the new PBP in the spore may be associated with the sporulation process. The major PBP band (mol wt: 27,000) present in all stages of the life cycle of these strains, may be characteristic of S. griseus while the other PBPs reflect certain stages of the life cycle. A new method was developed for the production of spore protoplasts by consecutive enzymatic treatments.Abbreviation PBP penicillin-binding protein     

A-factor and streptomycin biosynthesis inStreptomyces griseus

Accumulating data have shown that the metabolites with a -butyrolactone ring functions as an autoregulatory factor or a microbial hormone for the expression of various phenotypes not only in a variety ofStreptomyces spp. but also in the distantly related bacteria. A-factor, as a representative of this type of autoregulators, triggers streptomycin biosynthesis and cellular differentiation inStreptomyces griseus. A model for the A-factor regulatory cascade on the basis of recent work is as follows. At an early step in the A-factor regulatory relay, the positive A-factor signal is first received by an A-factor receptor protein that is comparable in every aspect to eukaryotic hormone receptors, and then, via one or more regulatory steps, transmitted to an A-factor-responsive protein that binds to the upstream activation sequence of thestrR gene, a regulatory gene in the streptomycin biosynthetic gene cluster. The StrR protein thus induced appears to activate the other streptomycin biosynthetic genes. This review summarizes the characteristics of A-factor as a microbial hormone and the A-factor regulatory relay leading to streptomycin production.     

Feeding Ecology of Sympatric Mouse Lemur Species in Northwestern Madagascar

We performed a comparative pilot study on vertical space use and feeding ecology of 2 closely related sympatric mouse lemur species in northwestern Madagascar. We recorded feeding behavior and the use of vertical forest strata for 6 gray and 4 golden-brown mouse lemur females that we followed for 120 h. We carried out feeding experiments and analyzed fecal samples for food remains. Both species showed no significant difference in use of forest strata. They had a similar overall diet, with insect secretions and gum as main plant food resources; arthropod remains occurred in about half of all fecal samples. Both lemurs used in common >50% of the plant species that each consumed, which accounts for ≥70% of all individual plants used. However, both species used >40% of their feeding plant species exclusively and seemed to differ in their degree of specialization on certain plant species.     

PCR-mediated screening and cloning of a malate synthase genefrom Streptomyces griseus NCIMB 9001

Malate synthase is an essential metabolic enzyme of the glyoxylate bypass that makes possible the replenishment of carbon intermediates to cells grown on acetate. A polymerase chain reaction (PCR)-based molecular screening investigation of full-length malate synthase genes from Streptomyces spp. was initiated by our group. To this end, consensus primers were designed based on known streptomycete malate synthase sequences and successful amplification was obtained for Streptomyces griseus, S. fimbriatus and S. lipmanii. The putative full-length malate synthase gene from S. griseus was subsequently cloned, sequenced and expressed. Sequence analysis of this gene showed very high identity with other streptomycete malate synthase genes. Furthermore, high malate synthase activity was detected after heterologous expression in Escherichia coli, thus demonstrating successfully the rapid cloning and functional verification of a streptomycete malate synthase gene. Growth studies of S. griseus revealed that malate synthase activity was induced by the presence of acetate, which is a two-carbon source. Interestingly, the activity peaked during late growth phase when the biomass was declining, suggesting that the enzyme may have a late role in metabolism.     

Circadian variations in pinealocytes of the Chinese hamster,Cricetulus griseus

Summary Circadian morphological variations of pinealocytes in the superficial pineal of the Chinese hamster (Cricetulus griseus) were studied using quantitative electron-microscopic techniques. The volume of the nucleus and cytoplasm of pinealocytes exhibited similar circadian variations, with the maximum around the middle of the light period and the minimum during the first half of the dark period. Synaptic ribbons in pinealocytes were classified into three groups, type-1, –2 and –3 synaptic ribbons, which appeared as rods, round or irregular bodies and ring-shaped structures, respectively; a synaptic ribbon index was determined for the respective types. The synaptic ribbon index was expressed as the number of synaptic ribbons in the pinealocyte profile representing the cell size. The type-1 synaptic ribbon index, which was smallest during the second half of the light period, was increased during the dark period. The length of straight or slightly curved rods showed a 24-h change similar to that of the type-1 synaptic ribbon index; the length of the rods was maximal during the first half of the dark period and minimal at the end of the light period. There was no apparent circadian variation in the type-2 synaptic ribbon index. The type-3 synaptic ribbon index was higher during the light period than during the dark period; the index attained zero 3h after the onset of darkness and, thereafter, increased gradually.     

Feeding ecology of the long-tailed macaque(Macaca fascicularis) in Kalimantan Tengah,Indonesia

I studied long- tailed macaque (Macaca fascicularis)feeding behavior and ecology as part of a larger behavioral ecological study at the Natai Lengkuas Station, Tanjung Puting National Park, Kalimantan Tengah, Indonesia. I collected data on feeding behavior via scan sampling of all visible individuals in the focal group (approximately 800 observation hours). I established vegetational plots and monitored them monthly to determine food availability and abundance. I found long- tailed macaques to be primarily frugivorous;leaves, flowers, insects and bark provided the remainder of the diet. They used at least 33 plant species as food sources, but >60% of the diet was provided by only 5 species. Based on previous vegetational analyses, these tree species were among the highest in relative density. However, selection ratios for 19 food species indicate that 13 of them were selected more often than expected. Long- tailed macaques appear to be selective feeders but can exploit a variety of food sources during periods of food scarcity.     

Effect of chitin sources on production of chitinase and chitosanase byStreptomyces griseus HUT 6037

The advantage of usingStreptomyces griseus HUT 6037 in the production of chitinase or chitosanase is that the organism is capable of hydrolyzing amorphous or crystal-line chitin and chitosan according to the type of the substrate used. We investigated the effects of the enzyme induction time and chitin sources, CM-chitosan and deacetylated chitosan (degree of deacetylation 75–99%), on production of chitosanase. We found that this strain accumulated chitosanase when cells were grown in the culture medium containing chitosanaceous substrates instead of chitinaceous substrates. The highest chitosanase activity was obtained at 4 days of cultivation with 99% deacetylated chitosan. Soluble chitosan (53% deacetylated chitosan) was found to induce chitinase as well as chitosanase. The specific activities of chitinase and chitosanase were 0.91 and 1.33 U/mg protein at 3 and 5 days, respectively. From the study of the enzymatic digestibility of various degrees of deacetylated chitosan, it was found that (GlcN)₃, (GlcN)₄ and (GlcN)₅ were produced during the enzymatic hydrolysis reaction. The results of this study suggested that the sugar composition of (GlcN)₃ was homogeneous and those of (GlcN)₄ and (GlcN)₅ were heterogeneous.     

Sex Differences in Captive Olive Baboon Behavior During the First Fourteen Days of Life

I discuss newborn baboon behavioral and proximity sex differences in a population of captive olive baboons (Papio anubis) living in a social group of >500 individuals. The data are based upon 20-min focal observations of 42 mother-newborn pairs (n = 27, n = 15) for infant-days 1–7 and 36 pairs (n = 23, n = 13) for infant-days 8–14 collected late-May through late-November 2001. I examined the first two weeks of infant life via behavioral, proximity, and approach-leave/contact analyses in order to determine whether behavioral sex differences exist during the first few days of life. I examine and analyze these 2 weeks independently due to different sample sizes. I used data from the total available sample population of 57 infants (n = 36, n = 21) to discuss birth, survivorship, and infant weight. Statistically significant age and/or age-sex interactions exist for all of the behavior and proximity measures during either infant-week 1 or 2. Moreover, there is a statistically significant difference in the birth sex ratio in the sample population but no significant difference in infant mortality by sex. There are also relative and significant differences in mothers' treatment of their newborn males and females. There are also some general tendencies for female newborns on average to suckle less and to explore more per focal observation than male infants do as they age. Conversely, male newborns average slightly more time per focal observation 1 m from the mother than do female infants. However, the observed differences may be influenced by maternal behavior in that mothers have higher rates of contact with their female than their male infants.     

Mother-Young Feeding Synchrony and Early Food Selection Differences in Eulemur fulvus

I tested the hypothesis that mother-young cofeeding correlates with a systematic similar food selection in wild Mayotte brown lemurs (Eulemur fulvus). I simultaneously recorded the feeding behavior of 4 maternal dyad members, from infant birth to weaning, and 10–12 mo of juvenile age, during 10-min focal periods, each separated by 5-min intervals over 10 mo. I recorded the solid food items selected for each feeding behavior at the level of specific plant part, along with the distance between the 2 individuals. I considered feeding behaviors simultaneous (between the young lemurs and their mothers) when the young began to eat a food item while the mother was already eating, regardless of the separation distance. During their first year, most of the feeding events of the young brown lemurs were initiated by their mothers. However, infants also selected different food items from those chosen by their mothers in almost one-third of cases, and the food selection dissimilarity was not attributable to an increase in the distance of separation. For juveniles, dissimilar food selection was significantly lower and linked to an increase in mother-juvenile separation distance. Thus, the substantial proportion of dissimilarity in solid foods selected by the infant during the synchronized feeding behaviors strongly suggests that social influences were not food-specific and might instead drive the acquisition of group feeding activity rhythm rather than food selection habits.     

Effects of melatonin on synaptic ribbons in pinealocytes of the Chinese hamster,Cricetulus griseus

Summary The effects of melatonin on synaptic ribbons (SR) in pinealocytes of the Chinese hamster (Cricetulus griseus) were examined. SR were classified into types 1, 2 and 3, which appear as rods, round or irregular bodies and ring-shaped structures, respectively; a synaptic ribbon index (SR index) was determined for the three types. Administration of two doses of 1.5 mg/kg melatonin at noon and 3 p.m. causes an increase in the type-1 and type-2 SR indices 3 h after the second injection in hamsters kept under alternating light and dark conditions (lights on from 7 a.m. to 7 p.m.). Likewise, in animals that are exposed to extended light for 6 h and receive two doses of melatonin at 7 p.m. and 10 p.m., an increase in the type-1 and type-2 SR indices occurs 3 h after the second injection. The increase in the type-2 SR index induced by melatonin administration to hamsters exposed to extended light is greater than the increase in the type-1 SR index under the same experimental conditions. Type-2 SR index, but not type-1 SR index, increases following bilateral superior cervical ganglionectomy. An increase in type-1 and type-2 SR indices occurs at 6 p.m. in ganglionectomized animals administered two doses of melatonin 6 h (noon) and 3 h (3 p.m.) before the time of sacrifice. No significant change is observed in type-3 SR index in animals subjected to any of the above treatments. The results indicate that exogenous melatonin may act directly on pinealocytes of the Chinese hamster to cause an increase in size and/or number of the type-1 and type-2 SR. Type 3-SR may have a role different from that of type-1 and type-2 SR; type-1 and type-2 SR may be functionally related.     

Photosynthesis,Transpiration, and Water Use Efficiency of Vegetative and Reproductive Shoots of Grassland Species from North-Eastern China

The differences in net photosynthetic rate (P _N), transpiration rate (E), and water use efficiency (WUE) between the vegetative and reproductive shoots of three native grass species from the grassland of northeastern China [grey-green and yellow green populations of Leymus chinensis (Trin.) Tzvel., Puccinellia tenuiflora (Griseb) Scrib & Merr, Puccinellia chinampoensis Ohwi] were compared. The two type shoots experienced similar habitats, but differed in leaf life-span and leaf area. The leaf P _N and WUE for the vegetative shoots were significantly higher than those for the reproductive shoots in the grasses, while their E were remarked lower in the dry season. Relative lower leaf P _N and WUE for the reproductive shoots of grassland grasses may explain the facts of lower seed production and the subordinate role of seed in the grassland renewal in north-eastern China.     

Comparative Feeding Ecology of Sympatric <Emphasis Type="Italic">Microcebus berthae and M. murinus</Emphasis>

Most Malagasy primate communities harbor a diverse assemblage of omnivorous species. The mechanisms allowing the coexistence of closely related species are poorly understood, partly because only preliminary data on the feeding ecology of most species are available. We provide an exemplary feeding ecology data set to illuminate coexistence mechanisms between sympatric gray and Madame Berthe’s mouse lemurs (Microcebus murinus, M. berthae). We studied their feeding ecology in Kirindy Forest/CFPF, a highly seasonal dry deciduous forest in western Madagascar. Between August 2002 and December 2007, we regularly (re-)captured, marked, and radiotracked females of both species. A combination of direct behavioral observations and fecal analyses revealed that both Microcebus species used fruit, arthropods, gum, insect secretions, and small vertebrates as food sources. However, Microcebus berthae and M. murinus differed in both composition and seasonal variation of their diets. Whereas the diet of Microcebus murinus varied seasonally and was generally more diverse, M. berthae relied mainly on insect secretions supplemented by animal matter. The differences were also reflected in a very narrow feeding niche of Microcebus berthae and a comparatively broad feeding niche of M. murinus. Resource use patterns of Madame Berthe’s and more so of opportunistic gray mouse lemurs broadly followed resource availability within the strongly seasonal dry forest. Feeding niche overlap between the 2 sympatric species was high, indicating that food resource usage patterns did not reflect niche partitioning, but can instead be explained by constraints due to food availability.     

Effect of continuous darkness on circadian morphological rhythms in pinealocytes of the Chinese hamster,Cricetulus griseus

Summary Effects of a short-term exposure to continuous darkness on 24-h morphological variations in pinealocytes in the superficial pineal of the Chinese hamster (Cricetulus griseus) were examined. Pinealocytes contained type-1, -2 and -3 synaptic ribbons (SR), which had a central dense structure showing rod-like, various and ring-like profiles, respectively, and the quantity of each type of SR was expressed by SR index. 24-h changes in the type-1 and type-3 SR indices persisted in darkness and thus may be endogenous in nature. As under alternating light and dark (LD) conditions, the type-2 SR indices were almost constant over a 24-h period under continuous darkness, but the indices were larger in animals under darkness than in those under LD conditions. The 24-h variations in the nuclear and cytoplasmic volumes were abolished after exposing animals to darkness for 7 days, suggesting that these rhythms may be regulated exogenously. The amount of condensed chromatin exhibited a circadian change; this rhythm persisted under darkness. The results suggest that 24-h variations in the nuclear and cytoplasmic volumes in pinealocytes of the Chinese hamster are regulated by mechanisms different from those controlling the rhythms in SR and chromatin, and that the changes in the nuclear and cytoplasmic volumes and chromatin are related to the change in synthetic activity of pinealocytes.     

Diet and Feeding Ecology of Woolly Monkeys in a Western Amazonian Rain Forest

I investigated the diet and feeding ecology of two social groups of woolly monkeys (Lagothrix lagotricha poeppigii) in Yasuní National Park, Ecuador between April 1995 and March 1996. Woolly monkeys in Yasuní were predominantly frugivorous, with fruits comprising ca. 77% of the yearly diet; the next most common food type in the diet was insect and other animal prey. The fruit diet of woolly monkeys in Yasuní is the most diverse yet recorded for any ateline primate, including spider monkeys (Ateles), which are often regarded as ripe fruit specialists: 208 distinct morphospecies of fruits were consumed by woolly monkeys either during the study or during several preceding months of pilot work. Nonetheless, close to one-third of the yearly diet came from just 3 plant genera—Inga, Ficus, and Spondias—and only 20 genera each contributed to 1% of the diet. For one study group, the proportion of ripe fruit in the diet each month was correlated with the habitat-wide availability of this resource, a pattern evidenced by several other ateline species. However, the relationship was not apparent in the second study group. The modal party size for feeding bouts on all food types was a single monkey, and, contrary to reports for other atelines, neither feeding party size nor the total number of feeding minutes that groups spent in food patches was well predicted by patch size. Both results highlight the independent nature of woolly monkey foraging. Given that woolly monkeys and closely-related spider monkeys focus so heavily on ripe fruits, their very different patterns of social organization are intriguing and raise the question of just how their ecological strategies differ. Two important differences appear to be in the use of animal prey and in the phytochemical composition of the ripe fruits that they consume: spider monkeys rarely forage for animal prey, and woolly monkeys seldom consume the lipid-rich fruits that are an important part of spider monkey diets.     

Mammalian-like differentiation of gastric cells in the shark Hexanchus griseus

Summary Gastric glands of submammalian vertebrates are formed by one single cell type known as the oxyntopeptic cell. This cell secretes both hydrochloric acid and pepsinogen. In mammals, this cell differentiates into an acid secreting cell and a pepsinogen secreting one. In the elasmobranch fish Hexanchus griseus we observed, by means of histological studies at the light-and electron-microscopic levels, two different cell types for the secretion of acid and zymogen. This organization represents an evolutionary divergence in a primitive animal, i.e., the appearance of a feature that is acquired much later in evolution, in mammals.     

Oil Palm Use by Adjacent Communities of Chimpanzees at Bossou and Nimba Mountains,West Africa

We investigated oil palm (Elaeis guineensis) use for feeding in 3 chimpanzee communities: Bossou and Seringbara in Guinea and Yealé in Côte d'Ivoire. Bossou was used as the benchmark for comparison. Bossou chimpanzees (Pan troglodytes verus) exhibit a wide range of oil palm targeted behaviors. We used direct observations of their two tool use, i.e., nut-cracking and pestle pounding, to establish strict and reliable criteria to ascertain the presence of comparable behaviors at the two adjacent Nimba sites. Based on monthly surveys of oil palms across the three sites, significant differences in patterns of use emerged. Bossou chimpanzees demonstrated the greatest frequency of oil palm use, while Seringbara chimpanzees, 6 km away, failed to exhibit any use and Yealé chimpanzees, 12 km away, showed all uses comparable to Bossou chimpanzees except pestle pounding and mature leaf pith-feeding. We examined the density and distribution of oil palms, tool availability for nut-cracking and pestle pounding, fruit, flower and nut availability, competition with sympatric species for fruit and nuts and the diversity of fruit species in the diet across the 3 sites. We found no clear difference in proximate environmental variables underlying observed variations in oil palm use among the 3 sites, yielding the conclusion that the differences are cultural. Assuming individual interchange between communities and the involvement of social learning in the intracommunity transmission and maintenance of oil palm uses, the result raises interesting questions about diffusion of behavior between neighboring chimpanzee communities.     

Feeding ecology of the proboscis monkey (Nasalis larvatus)

Proboscis monkey (Nasalis larvatus) feeding behavior and ecology were studied at the Natai Lengkuas Station, Tanjung Puting National Park, Kalimantan Tengah, Indonesia. Data on feeding behavior were collected using scan sampling during group follows. Three vegetational plots containing 1,732 trees were established and monitored monthly for changes in fruit, flower, and young leaf production. Basal area and canopy cover were calculated and used in estimating food abundance. Proboscis monkeys were found to be folivore/frugivores, specializing in seed consumption. At least 55 different plant species were used as food sources, with a marked preference for Eugenia sp. 3/4,Ganua motleyana and Lophopetalum javanicum. These tree species were among the most frequent and most dominant. However, proboscis monkeys were selective feeders; use of tree species as food sources was not based simply on relative density. During times of low food abundance and/or availability proboscis monkeys switched dietary strategies and increased dietary diversity. The average total home range was estimated to be 130.3 ha, with an average group density of 5.2 groups per km². The average biomass per km² was estimated to be 499.5 kg. Given their high biomass and predilection for consuming seeds of dominant species, proboscis monkeys may help to maintain and increase vegetational diversity.     

The effect of feedback regulation and in situ product removal on the conversion of sugar to cycloheximide by Streptomyces griseus

An addition of cycloheximide to cycloheximide-producing Streptomyces griseus cultures resulted in reductions in the production rate and in the conversion of sugar into cycloheximide. In situ cycloheximide adsorption was observed to enhance: total cycloheximide titers; productivities; and the conversion of sugar to cycloheximide. During the secondary metabolite-producing phase, sugar consumption was observed to be linearly dependent on cycloheximide productivity. From this analysis a true product yield and maintenance coefficient were estimated to be 0.08 g cycloheximide/g glucose and 0.028 g glucose/g cell-h, respectively. The sixfold difference between this true product yield and a theoretical value obtained from knowledge of the biosynthetic pathway is discussed. Since the maintenance sugar requirement for cycloheximide production is large, stimulation of biosynthesis through in situ adsorption significantly increases the overall efficiency of sugar conversion to this secondary metabolite.     

Feeding,reproductive and locomotor activities in diapausing and non-diapausing adults ofDrosophila

Feeding, reproductive and locomotor activities of fourDrosophila species were studied under short and long daylengths at 15°C. A short daylength induced firm reproductive diapause in experimental strains ofD. subauraria andD. triauraria from northern Japan, but very shallow diapause in those ofD. lutescens andD. rufa from southern Japan. A subtropical strain ofD. triauraria had no diapause. The influence of diapause on feeding activity was detected only in aged (> 12 day old) females; that is, the feeding activity was lower in diapausing females than in non-diapausing ones. Females that do not produce eggs would not require so much energy. On the other hand, young adults of the study species exhibited a high feeding activity and rapidly increased bodyweight irrespective of sex and the diapause state. They would need nutrition to build up their adult body. In males, the feeding activity decreased with age irrespective of the diapause state. Males would not require so much energy for reproductive activity. Diapausing males became heavier than non-diapausing males, perhaps because they accumulated triacylglycerols in fat bodies. However, female bodyweight did not differ by the diapause state, perhaps because diapausing females accumulated triacylglycerols and reproducing females had eggs in their ovaries. InD. triauraria, diapausing individuals exhibited somewhat lower locomotor activity than non-diapausing ones.