Leukotriene B4 Release and Polymorphonuclear Cell Infiltration in Spinal Cord Injury

Activation of arachidonic acid occurs after spinal cord injury. Leukotriene B4 is a lipoxygenase metabolite of arachidonic acid. In a rat model of experimental spinal cord injury, we found that the leukotriene B4 content was less than the sensitivity of our assay (8 pg/mg of protein) in non-traumatized spinal cord. Leukotriene B4 was detectable in traumatized cord (mean +/- SE, 25 +/- 5 pg/mg of protein; n = 3). Release of leukotriene B4 from spinal cord slices into the incubation medium was also noted after trauma (9 +/- 1 pg/mg of protein; n = 12) and was enhanced by exposure of traumatized spinal cord slices to the calcium ionophore A23187 (375 +/- 43 pg/mg of protein; n = 12). The amount of leukotriene B4 released corresponded to the extent of post-traumatic polymorphonuclear cell infiltration determined by a myeloperoxidase assay. Results from this study suggest that the source of leukotriene B4 in spinal cord injury is infiltrating polymorphonuclear cells.     

Effects of NMDA Receptor Blockade During the Early Development Period on the Retest Performance of Adult Wistar Rats in the Elevated Plus Maze

The elevated plus maze (EPM) is an animal model of anxiety used to test the effects of anxioselective drugs. The loss of the anxiolytic effect of drugs during the second exposure to the EPM is called the “one trial tolerance” (OTT) phenomenon. The present study was designed to investigate the relationship between the OTT phenomenon and N-methyl-d-aspartate (NMDA) receptor blockade in the early developmental period of rats. NMDA receptor blockade was accomplished using MK-801 treatment given between postnatal days 20–30. Beginning on postnatal day 20, the rats were subcutaneously injected with MK-801 twice a day at the nape of the neck for a period of 10 days (0.25 mg/kg). Increased open arm exploration was observed in MK-801-treated rats during trial 1 (p = 0.001) and trial 2 (p = 0.003). The rats spent less time in the closed arms as compared to the saline animals in trial 1 (p = 0.006), and this time decreased further in trial 2 (p = 0.02). The fecal boli of the MK-801 group was decreased in trial 1 as compared to the saline group (p = 0.01), but was not significantly different in trial 2 (p = 0.08). In conclusion, NMDA receptor blockade using MK-801 produced an anxiolytic-like effect in trials 1 and 2. Furthermore, OTT was not affected by NMDA receptor blockade.     

Nuclear DNA content variation of three Miscanthus species in China

In order to estimate the variation in nuclear genome size in Miscanthus, flow cytometry of nuclei stained by propidium iodide was carried out using 36 populations of three Miscanthus species: M. lutarioriparius, M. sacchariflorus and M. sinensis, which were sampled from cold northern to warm and humid southern and central China, as well as near the sea level in eastern China to mountains in western China. The DNA content of diploid was 4.37 ± 0.02 pg/2C in M. lutarioriparius, 4.37 ± 0.01 pg/2C in M. sacchariflorus, and 5.37 ± 0.03 pg/2C in M. sinensis, respectively. There was no intraspecific variation in the three Miscanthus species at the diploid level, suggesting that the genome size was stable within species and the diverse environments did not induce variation in genome size at the diploid level. However, tetraploid populations were found in M. lutarioriparius and M. sacchariflorus, and their genome sizes were 8.56 and 8.54 pg, respectively, which are lower than expected values (8.74 pg), indicating the genome downsizing after polyploidization in the genus. Our results showed that the plant height of M. lutarioriparius was the highest one among the three species and the species was more closely related to M. sacchariflorus than M. sinensis. The intra-species genomic variation and inter-species differentiation in Miscanthus species provide important genetic and genomic information for the development of Miscanthus, especially for the endemic species, M. lutarioriparius, (together with Miscanthus × giganteus) which are now emerging as a key bio-energy crop because of their high yields and strong adaptability.     

Spontaneous and Amphetamine-Evoked Release of Cerebellar Noradrenaline After Sensorimotor Cortex Contusion: An In Vivo Microdialysis Study in the Awake Rat

Abstract: Microdialysis sampling combined with HPLC was used to assess spontaneous and d -amphetamine (AMPH)-evoked release of noradrenaline (NA) in the cerebellum 1 day after probe implantation and 1 day after contusion of the right sensorimotor cortex (SMCX) in rats. In normal controls the mean β SEM basal NA release was 10.08 β 0.97 pg in the left cerebellar hemisphere and 8.21 β 1.17 pg in the right hemisphere 22–24 h after probe implantation. The average β SEM NA release in a 3-h period after administration of AMPH (2 mg/kg, i.p.) increased to 453 β 47.35 pg in the left and to 402 β 49.95 pg in the right cerebellar hemisphere. NA release (range of 413–951% increase over baseline) was maximal 20–40 min postdrug, returned to basal levels within 5 h, and remained unchanged for the 22–24-h postdrug measurement period. Animals with a focal SMCX contusion had a marked depression of both spontaneous and AMPH-evoked NA release. Mean β SEM basal NA release was 4.84 β 1.09 pg in the left and 4.95 β 0.43 pg in the right cerebellar hemisphere from 22 to 24 h postinjury, with NA levels increasing to 259 β 75.44 and 219 β 23.45 pg in the respective hemispheres over a 3-h period after AMPH. The maximal AMPH-induced increase in NA release ranged from 522 to 1,088% of basal levels in contused rats, with NA release returning to predrug levels within 5 h and remaining depressed for at least 48 h postinjury. These data indicate that although neocortical injury results in a bilateral reduction of extracellular levels of NA in cerebellum, AMPH-releasable NA stores are present in the cerebellum. These effects may be related to locomotor impairments and AMPH-facilitated behavioral" recovery after cortical injury.     

Impaired muscarinic type 3 (M3) receptor/PKC and PKA pathways in islets from MSG-obese rats

Monosodium glutamate-obese rats are glucose intolerant and insulin resistant. Their pancreatic islets secrete more insulin at increasing glucose concentrations, despite the possible imbalance in the autonomic nervous system of these rats. Here, we investigate the involvement of the cholinergic/protein kinase (PK)-C and PKA pathways in MSG β-cell function. Male newborn Wistar rats received a subcutaneous injection of MSG (4 g/kg body weight (BW)) or hyperosmotic saline solution during the first 5 days of life. At 90 days of life, plasma parameters, islet static insulin secretion and protein expression were analyzed. Monosodium glutamate rats presented lower body weight and decreased nasoanal length, but had higher body fat depots, glucose intolerance, hyperinsulinemia and hypertrigliceridemia. Their pancreatic islets secreted more insulin in the presence of increasing glucose concentrations with no modifications in the islet-protein content of the glucose-sensing proteins: the glucose transporter (GLUT)-2 and glycokinase. However, MSG islets presented a lower secretory capacity at 40 mM K⁺ (P < 0.05). The MSG group also released less insulin in response to 100 μM carbachol, 10 μM forskolin and 1 mM 3-isobutyl-1-methyl-xantine (P < 0.05, P < 0.0001 and P < 0.01). These effects may be associated with a the decrease of 46 % in the acetylcholine muscarinic type 3 (M3) receptor, and a reduction of 64 % in PKCα and 36 % in PKAα protein expressions in MSG islets. Our data suggest that MSG islets, whilst showing a compensatory increase in glucose-induced insulin release, demonstrate decreased islet M3/PKC and adenylate cyclase/PKA activation, possibly predisposing these prediabetic rodents to the early development of β-cell dysfunction.     

Cerebral Hemorrhage Increases Plasma Concentrations of Noradrenalin and Creatine Kinase MB Fraction with Induction of Cardiomyocyte Damage in Rats

The incidence of cardiac damage is high during acute cerebral hemorrhage. The animal data on the relationship between cerebral apoplexy and cardiac damage are lacking. Thus, the aim of the study was to evaluate the effects of cerebral hemorrhage on plasma concentrations of monoamine transmitter noradrenalin (NA), creatine kinase muscle and brain (CK-MB) isoenzyme fraction, and cardiomyocyte changes in the rat model. In this study, 140 Wistar rats were randomly and equally divided into experimental and control groups, and collagenase was injected into the right caudate nucleus to induce cerebral hemorrhage in the experimental group. Plasma NA was analyzed using high-performance liquid chromatography with electrochemical detection and serum CK-MB was measured by enzyme reaction rate method. We found that both NA and CK-MB were elevated (p < 0.05) at 6 h after cerebral hematoma formation; the levels were 2.46 ± 0.05 μg/L and 3.51 ± 0.23 μkat/L, respectively. NA and CK-MB concentrations reached peak levels at 24 h which were found to be 3.52 ± 0.06 μg/L and 5.47 ± 0.49 μkat/L, respectively. Thereafter, NA and CK-MB concentrations decreased gradually. Plasma NA declined to the preoperative level (1.66 ± 0.03 μg/L) at 72 h, while CK-MB level (2.71 ± 0.17 μkat/L) was found to be still higher than its preoperative level. It was, therefore, concluded that plasma NA might be involved in the induction and development of cardiomyocytes damage during cerebral hemorrhage.     

Maternal-Neonatal Pheromone/Interomone Added to Cat Litter Improves Litter Box Use and Reduces Aggression in Pair-Housed Cats

Introducing a new cat into a household with one or more resident cats can be a significant source of stress for the cats involved. These studies sought to determine if rabbit maternal-neonatal pheromone (2-methyl-2-butenal [2M2B]) in litter impacted cat social behaviors and litter box use. Study 1 determined that cats preferred to eliminate in litter containing 2M2B; other semiochemicals tested did not change litter box use. Cats prone to aggression were identified in an intermediate pilot study, and eight pairs of these cats were selected for Study 2. In Study 2, cat pairs were provided litter containing either vehicle or 2M2B for 24 hours. Cats experiencing control litter displayed more aggression during the first 6 hours (p < .01) and spent more time using the litter box 12 hours and 18 hours after pairing compared with cats experiencing litter with 2M2B (p = .02). These results suggest 2M2B-infused cat litter may act as an interomone in cats housed domestically to prevent initial occurrences of aggression and may improve cat welfare in multicat households.     

Analysis of Proteins Expressed by an Abiotic Stress Tolerant Pseudomonas putida (NBAII-RPF9) Isolate Under Saline and High Temperature Conditions

Pseudomonas putida (NBAII-RPF9) was identified as an abiotic stress tolerant bacterium capable of growing at 45 °C as well as in 1 M NaCl. The proteins expressed by this bacterium when subjected to these two stresses were analyzed by 2D gel and MALDI-TOF/MS. Two parameters viz., heat/saline shock (20 min at 45 °C/1 M solid NaCl added at mid log phase and incubated for 1 h) and heat/saline tolerance (24 h growth at 45 °C/in 1 M NaCl) were studied. Under heat shock 13 upregulated proteins and 1 downregulated protein were identified and under tolerance 6 upregulated proteins were identified. GroES and GroEL proteins were expressed under both tolerance and shock. Under saline shock 11 upregulated proteins were identified whereas under saline tolerance 6 upregulated proteins were identified and all these proteins had pI between 3 and 10 with molecular weights ranging from 14.3 to 97 kDa. Aspartate carbamoyltransferase was common under both the saline conditions studied. The analysis revealed involvement of heat stress responsive molecular chaperones and membrane proteins during heat stress. During salt stress, proteins involved in metabolic processes were found to be upregulated to favor growth and adaptation of the bacterium. Heat shock chaperones viz., DnaK and DnaJ were expressed under both saline and heat stress. This is the first report of protein profile obtained from a single bacterium under saline and heat stress and the studies reveal the complex mechanisms adapted by the organism to survive under high temperature or saline conditions.     

Litter dynamics and fine root production in Schizolobium parahyba var. amazonicum plantations and regrowth forest in Eastern Amazon

Forest plantations and agroforestry systems with Schizolobium parahyba var. amazonicum have greatly expanded in the Brazilian Amazon, generally as an alternative for reforesting degraded areas. To our knowledge there are no reports of above- and below-ground production in these forest systems. We quantified litter and fine root production in 6-yr old Schizolobium-based plantation forests (monospecific: MON, mixture: MIX, and agroforestry system: AFS) and in ~25-yr old regrowth forest (REG) over 8–12 months. We used litter traps and ingrowth cores to quantify litter and fine root production, respectively. Annual litter production was significantly lower in Schizolobium-based plantations (mean ± standard error, MON?=?5.92?±?0.15, MIX?=?6.08?±?0.13, AFS?=?6.63?±?0.13 Mg ha^?1 year^?1) than in regrowth forest (8.64?±?0.08 Mg ha^?1 year^?1). Schizolobium-based plantations showed significantly higher litter stock (MON?=?7.7?±?1.0, MIX?=?7.4?±?0.1 Mg ha^?1) than REG (5.9?±?1.3 Mg ha^?1). Total fine root production over an 8-month period was significantly higher in Schizolobium-based plantations (MON?=?3.8?±?0.2, MIX?=?3.4?±?0.2, AFS?=?2.7?±?0.1 Mg ha^?1) than in REG (1.1?±?0.03 Mg ha^?1). Six-yr old Schizolobium-based plantations and ~25-yr old regrowth forests showed comparable rates of litter + fine root production, suggesting that young forest plantations may be an interesting alternative to restore degraded areas due to early reestablishment of organic matter cycling under the studied conditions.     

The Central Analgesic Mechanism of YM-58483 in Attenuating Neuropathic Pain in Rats

Calcium channel antagonists are commonly used to treat neuropathic pain. Their analgesic effects rely on inhibiting long-term potentiation, and neurotransmitters release in the spinal cord. Store-operated Ca²⁺channels (SOCCs) are highly Ca²⁺-selective cation channels broadly expressed in non-excitable cells and some excitable cells. Recent studies have shown that the potent inhibitor of SOCCs, YM-58483, has analgesic effects on neuropathic pain, but its mechanism is unclear. This experiment performed on spinal nerve ligation (SNL)-induced neuropathic pain model in rats tries to explore the mechanism, whereby YM-58483 attenuates neuropathic pain. The left L5 was ligated to produce the SNL neuropathic pain model in male Sprague–Dawley rats. The withdrawal threshold of rats was measured by the up–down method and Hargreaves’ method before and after intrathecal administration of YM-58483 and vehicle. The SOCCs in the spinal dorsal horn were located by immunofluorescence. The expression of phosphorylated ERK and phosphorylated CREB, CD11b, and GFAP proteins in spinal level was tested by Western blot, while the release of proinflammatory cytokines (IL-1β, TNF-α, PGE2) was measured by enzyme-linked immunosorbent assay (ELISA). Intrathecal YM-58483 at the concentration of 300 μM (1.5 nmol) and 1000 μM (10 nmol) produced a significant central analgesic effect on the SNL rats, compared with control + vehicle (n = 7, P < 0.001). However, both could not prevent the development of neuropathic pain, compared with normal + saline (P < 0.001). Immunofluorescent staining revealed that Orai1 and STIM1 (the two key components of SOCCs) were located in the spinal dorsal horn neurons. Western blot showed that YM-58483 could decrease the levels of P-ERK and P-CREB (n = 10, #P < 0.05), without affecting the expression of CD11b and GFAP (n = 10, #P > 0.05). YM-58483 also inhibited the release of spinal cord IL-1β, TNF-α, and PGE2, compared with control + vehicle (n = 5, #P < 0.001). The analgesic mechanism of YM-58483 may be via inhibiting central ERK/CREB signaling in the neurons and decreasing central IL-1β, TNF-α, and PGE2 release to reduce neuronal excitability in the spinal dorsal horn of the SNL rats.     

Role of angiotensin II and oxidative stress on renal aquaporins expression in hypernatremic rats

The aim of this study was to assess whether endogenous Ang II and oxidative stress produced by acute hypertonic sodium overload may regulate the expression of aquaporin-1 (AQP-1) and aquaporin-2 (AQP-2) in the kidney. Groups of anesthetized male Sprague–Dawley rats were infused with isotonic saline solution (control) or with hypertonic saline solution (Na group, 1 M NaCl), either alone or with losartan (10 mg kg^?1) or tempol (0.5 mg min^?1 kg^?1) during 2 h. Renal function parameters were measured. Groups of unanesthetized animals were injected intraperitoneally with hypertonic saline solution, with or without free access to water intake, Na+W, and Na?W, respectively. The expression of AQP-1, AQP-2, Ang II, eNOS, and NF-kB were evaluated in the kidney by Western blot and immunohistochemistry. AQP-2 distribution was assessed by immunofluorescence. Na group showed increased natriuresis and diuresis, and Ang II and NF-kB expression, but decreased eNOS expression. Losartan or tempol enhanced further the diuresis, and AQP-2 and eNOS expression, as well as decreased Ang II and NF-kB expression. Confocal immunofluorescence imaging revealed labeling of AQP-2 in the apical plasma membrane with less labeling in the intracellular vesicles than the apical membrane in kidney medullary collecting duct principal cells both in C and Na groups. Importantly, our data also show that losartan and tempol induces a predominantly accumulation of AQP-2 in intracellular vesicles. In unanesthetized rats, Na+W group presented increased diuresis, natriuresis, and AQP-2 expression (112?±?25 vs 64?±?16; *p?<?0.05). Water deprivation increased plasma sodium and diuresis but decreased AQP-2 (46?±?22 vs 112?±?25; §p?<?0.05) and eNOS expression in the kidney. This study is a novel demonstration that renal endogenous Ang II–oxidative stress, induced in vivo in hypernatremic rats by an acute sodium overload, regulates AQP-2 expression.     

Impaired deformability of erythrocytes in diabetic rat and human: investigation by the nickel-mesh-filtration technique

Comprehensive research to quantify the deformability of erythrocytes in diabetic animals and humans has been lacking. The objective of this study was to compare the impairment of erythrocyte deformability in diabetic rats and patients by use of the same rheologic method. Deformability was investigated in streptozotocin-induced diabetic rats and diabetic patients, by using the highly sensitive and quantitative nickel-mesh-filtration technique. Erythrocyte filterability (whole-cell deformability) was defined as flow rate of hematocrit-adjusted erythrocyte suspension relative to that of saline (%). Hematological and biochemical data for diabetic rats did not differ from those for age-matched control rats except for hyperglycemia and malnutrition. Erythrocyte filterability for diabetic rats was significantly lower than that for control rats (69.4 ± 10.1%, n = 8, compared with 83.1 ± 4.2%, n = 8; p < 0.001). Likewise, erythrocyte filterability for diabetic patients was significantly impaired compared with that for controls (87.6 ± 3.4%, n = 174, compared with 88.6 ± 2.1%, n = 51; p = 0.046). Stepwise multiple regression analysis revealed that this impairment was mostly attributable to associated obesity (BMI, p = 0.029) and glycemic stress (HbA1c(JDS), p = 0.046). We therefore conclude that erythrocyte filterability is commonly impaired in diabetic rats and in humans. Moreover, metabolic risk accumulation further impairs erythrocyte filterability, resulting in derangement of the microcirculation.     

Effect of melatonin on brain oxidative damage induced by traumatic brain injury in immature rats

Progressive compromise of antioxidant defenses and free radical-mediated lipid peroxidation, which is one of the major mechanisms of secondary traumatic brain injury (TBI), has also been reported in pediatric head trauma. In the present study, we aimed to demonstrate the effect of melatonin, which is a potent free radical scavenger, on brain oxidative damage in 7-day-old rat pups subjected to contusion injury. Whereas TBI significantly increased thiobarbituric acid reactive substances (TBARS) levels, there was no compensatory increase in the antioxidant enzymes such as superoxide dismutase (SOD) and glutathione peroxidase (GPx) 24 hours after TBI in 7-day-old rats. Melatonin administered as a single dose of 5 mg/kg prevented the increase in TBARS levels in both non-traumatized and traumatized brain hemispheres. In conclusion, melatonin protects against oxidative damage induced by TBI in the immature brain.     

Influence of vegetation structure on the small mammal community in a shortgrass prairie ecosystem

The structure of vegetation, and how this structure varies across a landscape, is crucial to understanding the distribution of wildlife species. Between 2002 and 2004, we sampled small mammal communities and measured vegetation structure at 185 locations across a range of disturbance regimes in a shortgrass prairie ecosystem in southeastern Colorado, USA. At each sampling location, the local disturbance regime was some combination of varying intensity of livestock grazing, military training activity, and fire. Vegetation structural characteristics measured included percent bare ground, basal cover, litter, shrub density, and mean grass and shrub height. Rodent communities were described by richness, diversity, total and per capita biomass, and species abundances. Northern grasshopper mice (Onychomys leucogaster), Ord's kangaroo rats (Dipodomys ordii), silky pocket mice (Perognathus flavus), western harvest mice (Reithrodontomys megalotis), white-footed mice (Peromyscus leucopus), southern plains wood rats (Neotoma micropus), thirteen-lined ground squirrels (Spermophilus tridecemlineatus), deer mice (Peromyscus maniculatus), and spotted ground squirrels (Spermophilus spilosoma) accounted for >99 % of all captures. Canonical correlation analysis was used to assess the relationship between small mammals and vegetation structure. The first two canonical variates explained over 50 % of the variation in vegetation structure and were related to the ratio of bare ground to basal coverage and litter accumulation. Rodent community indices were most strongly related to litter accumulation and shrub density, though the models had low explanatory power. Our results agreed with published findings regarding microhabitat associations and indicated small mammal communities benefited from a system of interacting disturbances and the resulting landscape mosaic.     

Ghrelin is a Regulator of Cellular Apoptosis and Proliferation in the Rat Ovary

Apoptosis and proliferation are the common and essential events of reproductive function and development in the ovary, especially during follicular growth and atresia or luteal regression. Therefore, this study was set to investigate the influence of ghrelin treatment on apoptosis and proliferation specific indices in the rat ovary. Twenty-eight adult female Wistar rats were randomly allocated into control and treatment groups. Treatment group (n = 14) received 3 nmol of ghrelin as subcutaneous injection for 14 consecutive days or vehicle (normal saline) to the control rats. The animals from each group were equally sacrificed on days 9 and 14 after onset of ghrelin treatment and their ovaries were taken for immunohistochemical evaluation and caspase-3 assay. Accumulation of apoptosis-associated peptide Bax was significantly reduced following ghrelin treatment particularly in granulosa and luteal cells on day 14 (P < 0.01). In contrast, immunoreactivity against anti-apoptotic protein Bcl-2 was significantly elevated in ghrelin-exposed animals in granulosa, theca and luteal cells (P < 0.05). However, ghrelin administration was not able to change caspase-3 activity prominently, so that the means of enzyme activity were not statistically significant between groups (P > 0.05). Moreover, significant up-regulation of proliferation-associated peptide PCNA was also seen in the granulosa, theca and luteal cells of ghrelin-treated rats by day 14 (P < 0.05), but not on day 9. These findings indicate the first evidence of ghrelin involvement in the control of key gonadal functions, apoptosis and proliferation in the rat ovary, which is mainly mediated through decrease in Bax/Bcl-2 ratio consistent with upstream of PCNA level, however not depends on the reduction of caspase-3 activation. This may have potential implications that ghrelin can be considered as an apoptotic modulator of some ovarian disorders.     

Litter- and soil carbohydrate-carbon stocks in 2-, 4- and 10-year-old improved fallows in eastern Zambia

This study evaluated the effects of tree species and sites on soil carbohydrates, litterfall, and litter chemistry in 2-, 4- and 10-year-old improved fallows at three sites in eastern Zambia. Between April 2002 and August 2003, litter was collected in 2-year-old tree fallows at Kalichero, Kalunga and Msekera for chemical analyses. Soil samples collected at 0–30 cm from all experiments were analysed for total soil organic carbon (SOC), but only those from 4- and 10-year-old fallows were analysed for carbohydrates. Soil arabinose- and mannose-C stocks, and carbohydrate-C percentages of SOC (7.7–20.6 %) significantly (P < 0.05) differed across tree species in 10-year-old coppicing fallows at Msekera. Converting M + F to improved fallows resulted in a decline in monosaccharide-C, carbohydrate-C stocks and carbohydrate-C percentage of SOC. There were significant (P < 0.05) variations in litterfall (0.7–2.3 t ha^?1 year^?1) and litter C contents (0.3–1.1 t ha^?1 year^?1) across 2-year-old coppicing tree fallows at Msekera. Litter production and C contents were significantly greater on sandy soils at Kalunga than on fine-textured soils at Msekera. Litter chemical contents (C, N, AUR and polyphenols) and ratios (C:N, P:N, AUR:N, and (AUR + P):N) for litter in fallows differed significantly (P < 0.05) across species and sites. In this study, the role of litter in carbon cycling in improved fallows depended on tree species and site conditions.     

Carbon pools and fluxes in Bruguiera parviflora dominated naturally growing mangrove forest of Peninsular Malaysia

Estimation of carbon pools and fluxes were conducted in Bruguiera parviflora dominated naturally growing protected mangrove forest in Kuala Selangor Nature Park of Peninsular Malaysia. Above and below-ground carbon pools in seedlings were estimated from destructive methods. While, carbon pools and fluxes in saplings and trees were estimated from the derived allometric biomass equations. Carbon concentrations in different parts of seedlings, saplings and trees; and litter were measured during the dry, wet and intermediate seasons. Soil cores up to 1 m were analyzed to measure carbon concentrations and bulk densities at different depths. Litter standing crop of the study area was measured at the dry, wet and intermediate seasons and the range of total amount of litter standing crop was from 0.66 to 0.88 Mg/ha. Carbon concentration found to vary with the plant and litter parts; and also with the seasons and the range of mean weighted carbon concentration was 40.19 ± 0.87–56.52 ± 1.01 %. The carbon pools in seedling, sapling, tree and litter were 0.69, 0.51, 82.62 and 0.41 Mg C/ha respectively. However, 13.95 Mg C/ha/year of carbon flux was associated with saplings, trees and litter. The estimated carbon pool in the soil (up to 1 m) of the study area was 488.04 Mg C/ha. The findings of this study are the first estimation of carbon pools and fluxes in B. parviflora dominated sites and suggests the potential of this site as a carbon pool.     

Using flow cytometry and cytological analyses to assess the genetic stability of somatic embryo-derived plantlets from embryogenic Musa acuminata Colla (AA) ssp. malaccensis cell suspension cultures

Flow cytometry and chromosome counts were used to analyze the genetic stability of plants regenerated via Musa acuminata Colla (AA) ssp. malaccensis embryogenic cell suspension (ECS) cultures. These cultures were initiated from immature zygotic embryos (IZE) on Murashige and Skoog medium using nine different plant growth regulator (PGR) treatments. Highest percentage of embryogenic calli (EC) formation occurred on media with 4.5 μM 2,4-dichlorophenoxyacetic acid (2,4-D, 97 %), and 8.2 μM of picloram (Pi, 80 %) followed by 2.2 μM 2,4-D (75 %). Embryonic development was synchronized in liquid medium by filtration, and somatic embryo development was achieved with ECS aliquots overlaid on PGR-free medium. The EC medium composition and elapsed time of both short-term (~5 months old) and long-term (~2 years old) ECS cultures influenced plant regeneration, resulting in 65–99 % embryo germination and 50 to 100 % plant conversion. The mean 2C DNA content (1.23 ± 0.002 pg) and chromosome number (2n = 2x = 22) of M. acuminata ssp. malaccensis IZEs, seedlings and sucker plantlets were similar to the reported values. No significant differences were detected among IZEs before culturing, and none were found among the IZEs and leaves of control plants and the plants regenerated from short-term ECS lines when initiated with 2,4-D or Pi vis-à-vis the accession from which they originated. However, plants regenerated from the long-term ECS-L3 culture remained diploid, had the highest DNA content (2C = 1.283 ± 0.01 pg) and were clearly separate from the other regenerated and control plants.     

Controls on Litter Decomposition of Emergent Macrophyte in Dongting Lake Wetlands

Both litter composition and site environment are important factors influencing litter decomposition, but their relative roles in driving spatial variation in litter decomposition among wetlands remain unclear. The responses of mass loss and nutrient dynamics to site environment and litter source were investigated in Carex brevicuspis leaves from the Dongting Lake wetlands, China, using reciprocal transplants of litterbags. Litters originating from lower elevation (24–25 m; flooded for 180–200 days every year) and higher elevation (27–28 m; flooded for 60–90 days every year) sites were incubated simultaneously at lower and higher sites at three locations for 1 year. The remaining litter mass, N, P, and lignin contents were analyzed during decomposition. Initial N and P contents were richer in litters from lower sites than those from higher ones. The decomposition rate was higher for the litters originating from lower sites (0.0030 day^?1) than those from higher ones (0.0025 day^?1) and higher at lower sites (0.0031 day^?1) than at higher sites (0.0024 day^?1). Litters from lower sites displayed greater N and P mineralization than those from higher sites, whereas only P dynamics were affected by site elevation. The variation in litter decomposition rate among the different litter source groups was twice that among the different site elevation groups. These data indicate that, in wetlands ecosystems, litter composition plays a more important role in the speed of litter decomposition than site environment (here represented by site elevation).