Neurolinguistic Studies of Reading in Chinese.

Using the Chinese writing system, which is unique with respect to the composition of each character in terms of its graphic shape, as an example, this chapter addresses the neurobiological underpinnings of reading and writing and how these brain circuits are used in different languages.

Bisphenol A affects larval growth and advances the onset of metamorphosis in Drosophila melanogaster.

Exposure to Bisphenol A (BPA) has been reported to dysregulate endocrine pathways in a wide array of vertebrate species. The effects of BPA on invertebrate species are less well understood. We tested the effects of BPA on growth and development in Drosophila as these processes are governed by well-studied endocrine pathways. In this study, we tested the effects of three concentrations of BPA (0.1mg/L, 1mg/L or 10mg/L) and found a statistically significant increase in larval growth for the low dose treatment group (0.1mg/L), but not statistically significant for the high dose treatment group (10mg/L). BPA exposure resulted in an increased body size in treated animals at 48, 72 and 96h after egg laying (AEL). This finding reflects a non-monotonic dose-response that has been observed for an increasing number of endocrine disrupting compounds. The increase in growth rate found for all treatment groups was associated with a statistically significant increase in food intake observed at 72h AEL. Furthermore, we observed that the increased growth rate was coupled with an earlier onset of pupariation consistent with previously reported phenotypes resulting from increased activity of insulin/insulin growth factor signaling (IIS) in Drosophila. Since the timing of the onset of pupariation in Drosophila is controlled through the complex interaction of the IIS and the ecdysone signaling pathways, our findings suggest that BPA exerts its effects through disruption of endocrine signaling in Drosophila.

Hormonal control of birth behavior in the Tasmanian devil Sarcophilus harrisii.

In a number of marsupial species, females exhibit characteristic, stereotyped parturient behavior that facilitates the passage of the neonates to the pouch. In macropodids, this parturient behavior can be induced in non-pregnant females and males by treatment with either prostaglandin F2alpha (PGF2alpha) or oxytocin (OT). This study investigated the effects of PGF2alpha and OT on behavior of Tasmanian devils. Animals tended to sit or lie down quickly, with little vocalization, after treatment with PGF2alpha or OT, while after saline, the animals remained alert, seldom sat, and frequently vocalized. Hormone treatment caused increased respiration. Urogenital and pouch grooming, a characteristic element of parturient behavior in macropodids, was seen in only one devil after hormone treatment. However, no pouch or urogenital grooming was seen in videotape of a devil giving birth, so this may not be a feature of parturient behavior in this species. Overall behavior of males and females was very similar suggesting that the behavioral effects observed may be due to direct neural action of PGF2alpha or OT, rather than an indirect response to uterine or vaginal contractions caused by the hormones. This study is the first to demonstrate that OT results in PGF2alpha secretion as PGFM levels rose after OT injection.

Thyroid function and the development of endothermy in a marsupial, the Tasmanian bettong, Bettongia gaimardi (Demarest 1822).

The Tasmanian bettong (Bettongia gaimardi) is a small rat-kangaroo (marsupial) found only in Tasmania, Australia. The duration of pouch life is 15 weeks. Adults and older young display non-shivering thermogenesis and this paper examines the role of thyroxine in the development of endothermy in pouch young. Free thyroxine (T4) concentrations varied throughout pouch life. The mean (+/-SE) concentration was 6.2+/-1.9 pmol L(-1) in week 7, increased and peaked at 19.2+/-4.3 pmol L(-1) in week 12, and declined to 5.6+/-0.4 pmol L(-1) by week 20. This was similar to adult levels (3.2+/-3.8 pmol L(-1)). These concentrations showed significant differences. From pouch week 12 onwards, T4 injection raised oxygen consumption. Maximum levels of VO2 after T4 injection occurred at weeks 14-15. Although adult levels were lower, the increase in adult oxygen consumption after T4 injection was about 50%. Peak free T4 levels and metabolic responses to nor-adrenalin occur at week 12 and we hypothesize that thyroid hormone may facilitate the development of adrenergic-receptors in this species. The data presented in the paper further attest to the likely important role of the thyroid gland in the development of endothermy in marsupial pouch young.

Milk composition and growth in wild and captive Tasmanian bettongs, Bettongia gaimardi (Marsupialia).

Changes in milk composition (total solids, carbohydrate, protein, lipid and calculated gross energy content) during lactation in three groups of Tasmanian bettongs ( Bettongia gaimardi): free-living animals (wild group), captive animals offered a diet of dry dog food and apples ad libitum (ad lib group), and captive animals fed restricted amounts of the same diet (maintenance group) were related to growth rates (measured as body mass and head length) of their young. There were no significant differences in the concentration of milk solids among the three groups, but the wild group had higher lipid concentrations and the maintenance group had higher carbohydrate but lower protein concentrations. For all three groups, milk total solids increased through lactation from ca. 25% to ca. 45% and carbohydrate concentrations decreased from ca. 18% to about 3%. Protein concentrations increased from ca. 5% to ca. 10% in the wild and ad lib groups, but only from 4% to 8% in the maintenance group. Lipid concentrations increased in the wild and ad lib groups from ca. 4% to ca. 18%, but in the maintenance group only to ca. 7%. Calculated gross energy content of milk increased through lactation in the wild and ad lib groups (from ca. 500 kJ.100 ml(-1) to ca. 1,000 kJ.100 ml(-1)), but there was no significant increase in the maintenance group. The volume of milk produced increased to a peak just prior to permanent pouch vacation by the young, when the gross energy output in milk was 120-150 kJ.3 h(-1) in the wild and ad lib groups. On a daily basis this is equivalent to the milk energy output of larger wallabies, and helps to explain the relatively high growth rates of young Tasmanian bettongs. There were significant differences in growth rates among the groups, with the heaviest young always in the ad lib group. Thus differences in milk composition resulting from different planes of nutrition can lead to differences in growth rates of marsupial young.

Electret ion chambers for estimating alpha particle energy.

Electret ion chambers (EICs) are inexpensive, lightweight, robust, commercially available, passive, charge-integrating devices for measuring different radiations. At Florida International University's Hemispheric Center for Environmental Technology (FIU-HCET), EIC performance was evaluated with the goal of providing the U.S. Department of Energy (DOE) with a low-cost, low-risk means of alpha contamination monitoring using an existing commercial technology. During this evaluation, sensitivity of electrets in 960-mL hemispherical ion chamber (radius: 7.6 cm) was observed to increase with alpha particle energy because alpha particles expended their entire energy in the chamber volume. This observation prompted us to explore another EIC application: estimation of alpha particle energy. Correlation between electret mid-point voltage, alpha particle energy, and response was developed for the 960-mL EIC and was used to determine energy of an unknown source. The response (change in voltage per disintegration) is the ratio of the change of voltage per unit time and alpha particle activity. Since an EIC measures only the change in voltage per minute, to determine the alpha particle energy, the source activity should be accurately determined by another method.

Nonshivering thermogenesis in a marsupial (the tasmanian bettong Bettongia gaimardi) is not attributable to brown adipose tissue.

The Tasmanian bettong (Bettongia gaimardi, a marsupial) is a rat-kangaroo that increases nonshivering thermogenesis (NST) in response to norepinephrine (NE). This study attempted to assess whether brown adipose tissue (BAT), a specialized thermogenic effector, is involved in NST in the bettong. Regulatory NST, indicated by resting oxygen consumption (Vo2) of the whole body, was measured under conscious conditions at 20 degrees C with various stimuli: cold (4 degrees -5 degrees C) or warm (25 degrees C) acclimation, NE injection, and the beta3-adrenoceptor agonist (BRL) 37344. In line with the functional studies in vivo, the presence of BAT was evaluated by examining the expression of the uncoupling protein 1 (UCP1) with both rat cDNA and oligonucleotide probes. Both NE and BRL 37344 significantly stimulated NST in the bettong. After cold acclimation of the animals (at 4 degrees -5 degrees C for 2 wk), the resting Vo2 was increased by 15% and the thermogenic effect of NE was enhanced; warm-acclimated animals showed a slightly depressed response. However, no expression of UCP1 was detected in bettongs either before or after cold exposure (2 wk). These data suggest that the observed NST in the marsupial bettong is not attributable to BAT.

The role of laminin-1 in the modulation of radiation damage in endothelial cells and differentiation.

Microvascular dysfunction due to endothelial damage is often associated with the ionizing radiation used during cancer therapy. This radiation-induced capillary injury is a major factor in the inhibition of new vessel growth (angiogenesis) and in disease states such as radiation-induced pneumonitis and nephropathy. Many studies have examined the effects of radiation on endothelial cell function; however, little is known regarding the role the basement membrane plays in radiation-induced endothelial cell damage and angiogenesis. Therefore, we examined the effects of gamma radiation on aortic explants, and in vitro on three endothelial cell types (of artery, vein and capillary origin) irradiated with or without the basement membrane glycoprotein laminin-1. As expected, irradiation inhibited angiogenic sprouting of the aortic explants, endothelial cell proliferation, attachment, migration and differentiation in vitro in a dose-dependent manner. However, the effect of radiation on several of these processes in angiogenesis was reduced when the cells were irradiated on laminin-1. To further evaluate the effects of radiation on endothelial cells, we examined the expression of the vascular endothelial cell growth factor (VEGF) kinase domain region receptor in endothelial cells irradiated in the presence and absence of laminin-1. In endothelial cells irradiated on laminin-1, KDR expression increased 2.5-fold over control levels. Therefore, although radiation has a dose-dependent inhibitory effect on processes associated with angiogenesis in vitro, the presence of the basement membrane glycoprotein laminin-1 during irradiation decreases these effects.

Pregnancy in a marsupial, the Tasmanian pademelon (Thylogale billardierii).

The Tasmanian pademelon, Thylogale billardierii, is a medium-sized wallaby that adapts well to captivity and, unlike the well-studied tammar wallaby, is capable of breeding all year round. It may, therefore, be a useful model species for research into the reproductive biology of macropod marsupials. This paper presents necessary background data on histological changes in the reproductive organs and the rate of embryonic growth during gestation in T1 billardierii. After Day 4 RPY (removal of young from the pouch) the gravid and non-gravid uteri differ significantly in some histological parameters. The corpus luteum becomes active by Day 6 RPY and is fully developed by Day 14 RPY; it begins to degenerate from Day 19 RPY. Plasma progesterone concentrations through gestation follow a pattern similar to that in the tammar wallaby. There is an early, smaller, peak at Day 5 RPY, with plasma concentrations of progesterone then falling until the larger pre-partum peak occurs several days before birth.

Development of endothermy in a Tasmanian marsupial, Bettongia gaimardi and its response to cold and noradrenaline.

Marsupials at birth are ectothermic and gradually attain the ability to change their metabolic heat production during pouch life. How this process occurs in the bettong has been measured on 13 pouch young from week 1 until 3 weeks after pouch vacation (week 18). Oxygen consumption was measured at 35 degrees C (pouch temperature) and at 22 degrees C. The results at 35 degrees C showed an increase in metabolic rate from week 1 until week 12 when there was a decrease to near adult levels after pouch vacation. At 22 degrees C young bettongs had a lower metabolic rate (compared with measurements made at 35 degrees C) until week 9 after which there was an increase above measurements made at 35 degrees C. Noradrenaline had little effect until week 10 after which the metabolic rate (although measured at 35 degrees C) paralleled the levels measured at 22 degrees C. The free thyroxine level was low in early pouch life, increased to a peak at week 12 then decreased. Thermal conductance increased until week 10 after which it decreased, reaching values similar to those of adult bettongs by week 20. The results indicate that non-shivering thermogenesis occurs in this macropodoid marsupial. This phenomenon may be a phylogenetic difference between macropodid and non-macropodid marsupials as also suggested by Nicol et al. (1997).

The role of prostaglandin F2 alpha and oxytocin in the reproductive behavior of a marsupial, Bettongia gaimardi.

Bettongs give birth on the night that their large pouch young finally vacates the pouch. We have hypothesized that hormones associated with this birth are also involved in pouch vacation. Injections of prostaglandin F2 alpha (PGF2 alpha) caused contractions of the pouch. In a separate experiment PGF2 alpha caused pouch vacation; oxytocin had a similar effect but with a longer latency. In addition both hormones induced birth behavior in adult and immature females as well as in males. When a prostaglandin synthesis inhibitor (Finadyne) was given first, oxytocin failed to produce birth behavior or pouch vacation. This finding leads us to suggest that oxytocin exerts its behavioral effects via prostaglandin synthesis. These experiments are the first to demonstrate an effect by oxytocin on reproductive behavior in a marsupial.

Alpha-adrenergic stimulation of thermogenesis in a rat kangaroo (Marsupialia, Bettongia gaimardi).

The Tasmanian bettong (Bettongia gaimardi) is a small rat kangaroo without detectable brown adipose tissue (BAT). In view of our previous findings of norepinephrine-mediated increase in O2 consumption (Vo2) in the perfused hindlimb of this species, the present study examined the effect of alpha-adrenoceptors on the thermogenesis of conscious bettongs at rest by infusing adrenergic agents via an indwelling catheter in the tail vein. The resting Vo2 was 22.9 +/- 1.9 mmol.kg-1.h-1. Norepinephrine (10-80 micrograms.kg-1.min-1) stimulated Vo2 in a dose-dependent manner with the maximal increment of 46.7%. Naphazoline (an alpha 1,alpha 2-adrenergic agonist) and phenylephrine (an alpha 1-adrenergic agonist) also elicited increases in Vo2 with maximal values of 29.6 and 34.8%, respectively. In contrast, the alpha 2-adrenergic agonist clonidine had no significant effects. Both alpha- and beta-adrenergic blockers were used to antagonize the submaximal increase in Vo2 elicited by norepinephrine. As a dose of 10 micrograms.kg-1.min-1, the alpha-adrenergic blocker phentolamine abolished the effects of naphazoline and phenylephrine and reduced norepinephrine-induced Vo2 by 45.5%. The beta-adrenergic blocker propranolol inhibited the norepinephrine-induced Vo2 by 58.8% at 20 micrograms.kg-1.min-1. A combination of the two antagonists blocked 82.5% of the norepinephrine-induced Vo2. Pretreatment of the animal with indomethacin (1 mg/kg), a known inhibitor of prostaglandin cyclooxygenase, had no effect on phenylephrine-elicited Vo2. Taken together, these results indicate that alpha 1-adrenoceptors are directly involved in norepinephrine-induced thermogenesis in non-BAT tissue(s).

Effects of bromocriptine on lactation and plasma progesterone in Bettongia gaimardi, a Tasmanian macropodid marsupial.

Many macropodids exhibit lactational quiescence during which an embryo produced at post-partum mating is retained as a blastocyst in utero while a pouch young is sucking. The sucking stimulus maintains secretion of prolactin which may in some species inhibit the activity of the corpus luteum and, hence, the development of the embryo. When the sucking frequency decreases, the blastocyst resumes development. In the present study, the dopamine agonist bromocriptine, which in many mammals results in decreased secretion of prolactin from the pituitary gland, was administered to the Tasmanian bettong (Bettongia gaimardi) at two different doses (12.5 mg kg(-1) and 5 mg kg(-1)). Although lactation was affected by both doses, as evidenced by slower growth of the pouch young or their loss, in only two cases did the quiescent blastocyst activate at the time of injection. This occurred with the highest dose of bromocriptine and was reflected by earlier changes in plasma progesterone concentrations. It is concluded that the Tasmanian bettong is unusual in its lack of sensitivity to bromocriptine.

The association between basal body temperature, plasma progesterone and the oestrous cycle in a marsupial, the Tasmanian bettong (Bettongia gaimardi).

Basal body temperature, quantitative changes in vaginal smears and plasma concentrations of progesterone were measured during a number of oestrous cycles in Tasmanian bettongs (Bettongia gaimardi). These methods of monitoring the reproductive cycle were compared in an attempt to find a technique that allowed non-stressful assessment of the reproductive condition of the bettongs. Telemetric measurement of basal body temperature showed that there was a diurnal variation of 1.3 degrees C, typical of a nocturnal animal. During the oestrous cycle, there was a small, but not significant, peak in basal body temperature at oestrus (day 0) followed by a significant trough on day 2. There was a significant increase on day 3 and the temperature remained raised until day 10, during which time plasma progesterone concentrations are also high; the temperature then fell 2 days before oestrus. This fall corresponds to a decrease in concentration of plasma progesterone and in the numbers of leucocytes in vaginal smears. Telemetric measurement of body temperature may be useful as a non-stressful method of monitoring the oestrous cycle in bettongs.

Vasoconstrictors alter oxygen, lactate, and glycerol metabolism in the perfused hindlimb of a rat kangaroo.

The Tasmanian bettong (Bettongia gaimardi) is a small marsupial rat kangaroo without detectable brown adipose tissue (BAT). The hindlimb was perfused with constant flow at 25 degrees C after cannulation under anesthesia of the femoral artery and vein to one hindlimb. Norepinephrine (NE, 25 nM-2.5 microM) and vasopressin (VP, 10 nM-0.1 microM) each increased perfusion pressure, oxygen consumption (VO2), and lactate and glycerol efflux of the perfused hindlimb. NE-mediated increases in VO2 and the efflux of lactate and glycerol were unaffected by propranolol (10 microM) but were completely blocked by the further addition of phentolamine (10 microM). In contrast, serotonin (5-HT; 0.1-2.5 microM) inhibited VO2 and inhibited lactate efflux. The changes induced by NE, VP, and 5-HT were all rapidly reversed by nitroprusside. These results suggest that resting thermogenesis in bettong hindlimb can be differentially controlled by the vasculature, which may also contribute to the induced VO2. This vascular control of skeletal muscle VO2 appears widespread in homeotherm evolution.

Angiogenesis as a component of epithelial-mesenchymal interactions.

Here we review the role of angiogenesis as it pertains to the interactions between the epithelium and the mesenchyme, especially during tumor growth and metastasis. We illustrate and discuss several models of angiogenesis including endothelial tube formation on Matrigel. Finally, we examine angiogenic factors using the Matrigel model and investigate several other matrix molecules for their importance in angiogenesis and epithelial/stromal interactions.

Plasma progesterone levels in the pregnant female rat-kangaroo (Bettongia gaimardi).

Plasma progesterone levels were measured in female bettongs (small macropodid marsupials) under two natural regimes: (1) during "delayed" gestation (initiated by removal of pouch young, RPY) and (2) during the pregnancy prior to pouch vacation when a young still occupies the pouch (i.e., during lactation). Basal levels of progesterone were 0.15-0.5 ng/ml. There was a transient peak of progesterone (0.7 ng/ml) early in gestation at Day 4 RPY. After Day 6 RPY, progesterone levels remained elevated (1.2-1.5 ng/ml) until they dropped sharply to basal levels on the day of birth. This pattern of progesterone secretion during delayed gestation is similar to that seen in other marsupials, such as the tammar wallaby. There was no significant difference between the progesterone profiles of the two experimental groups. We deduce, then, that lactation had no effect on corpus luteum function (as assessed by plasma progesterone levels) in the pregnant bettong.

Maternal recognition of pregnancy in the Tasmanian bettong, Bettongia gaimardi (Marsupialia: Macropodoidea).

The fetus of the marsupial Bettongia gaimardi, the Tasmanian bettong, has both morphological and cytological effects upon the gravid uterus. Development of diapausing embryos or the initiation of oestrous cycles was achieved by removal of the pouch young (RPY). Increases in the diameter of the uterine basal endometrial glands were noted 3 and 4 days later. An animal at Day 5 after RPY had glands in the gravid uterus that were significantly larger than those in the non-gravid uterus (P less than 0.01). This difference was also found in non-pregnant animals before Day 11 and was believed to be due to the local presence of the corpus luteum. Thereafter, significant differences were only found in pregnant animals until parturition at Day 17 or 18 after RPY. These differences were attributed to the local effect of the fetus and reflect a 'maternal recognition of pregnancy', as found in other macropodoid species.

Testosterone levels in the Tasmanian bettong (Bettongia gaimardi).

The Tasmanian bettong (Bettongia gaimardi) is a small macropodid marsupial that is a continuous breeder. This study has partitioned testosterone into three fractions that vary to some extent throughout the year, coinciding with peaks and troughs in breeding, body weight, and testes volume. The three fractions determined were free, albumin bound, and sex hormone binding globulin (SHBG) bound testosterone. Concentrations of both albumin and SHBG varied significantly throughout the year with peaks in SHBG coinciding with lowered levels of free testosterone. Testosterone was also measured during maturation of male bettongs. There were significant regressions between weight or testes volume and the combined free and albumin bound testosterone. Maturity started near age 30 weeks and a body weight of 1.5 kg and was accompanied by a brief surge in testosterone levels.

Comparative lactation in two species of rat-kangaroo (Marsupialia).

1. Milk composition and energy content was measured in two related marsupials, Bettongia gaimardi and Potorous tridactylus. 2. Although protein content was consistently higher in bettong milk, lactational trends in both species are similar to those reported for other marsupials. 3. The faster relative growth rate of the bettong may be correlated with the increased protein and a higher milk intake.