The complex polyploid genome architecture of sugarcane

Sugarcane, the world's most harvested crop by tonnage, has shaped global history, trade and geopolitics, and is currently responsible for 80% of sugar production worldwide1. While traditional sugarcane breeding methods have effectively generated cultivars adapted to new environments and pathogens, sugar yield improvements have recently plateaued2. The cessation of yield gains may be due to limited genetic diversity within breeding populations, long breeding cycles and the complexity of its genome, the latter preventing breeders from taking advantage of the recent explosion of whole-genome sequencing that has benefited many other crops. Thus, modern sugarcane hybrids are the last remaining major crop without a reference-quality genome. Here we take a major step towards advancing sugarcane biotechnology by generating a polyploid reference genome for R570, a typical modern cultivar derived from interspecific hybridization between the domesticated species (Saccharum officinarum) and the wild species (Saccharum spontaneum). In contrast to the existing single haplotype ('monoploid') representation of R570, our 8.7 billion base assembly contains a complete representation of unique DNA sequences across the approximately 12 chromosome copies in this polyploid genome. Using this highly contiguous genome assembly, we filled a previously unsized gap within an R570 physical genetic map to describe the likely causal genes underlying the single-copy Bru1 brown rust resistance locus. This polyploid genome assembly with fine-grain descriptions of genome architecture and molecular targets for biotechnology will help accelerate molecular and transgenic breeding and adaptation of sugarcane to future environmental conditions.

Association between Smartphone Addiction and Breathing Pattern in Sedentary Young College-Going Students - A Cross-Sectional Study

BACKGROUND

The number of smartphone users has progressively increased worldwide. Altered biomechanics of the cervicothoracic spine and ribcage could limit the chest wall function that affects the respiratory muscles strength, reducing diaphragm function in smartphone users. This study aimed to compare breathing patterns between smartphone-addicted and -nonaddicted user groups.

OBJECTIVE

To find the association between excessive smartphone use and breathing pattern in sedentary young college-going students.

MATERIALS AND METHODS

This cross-sectional study includes 230 participants. The participants were screened for the inclusion and exclusion criteria and were asked to fill out a Smartphone Addiction Scale questionnaire. These breathing patterns were then assessed by self-evaluation of breathing questionnaire (SEBQ), manual assessment of respiratory motion (MARM), breath-holding test, and capnography.

RESULTS

The correlation of smartphone-addicted and -nonaddicted groups with breathing patterns was performed by Spearman rank correlation. Results show no significant association between the smartphone-nonaddicted and -addicted users.

CONCLUSION

This study concluded that excessive smartphone use and breathing patterns are not associated.

Vibrational and stochastic resonances in driven nonlinear systems: part 2

Nonlinearity is ubiquitous in both natural and engineering systems. The resultant dynamics has emerged as a multidisciplinary field that has been very extensively investigated, due partly to the potential occurrence of nonlinear phenomena in all branches of sciences, engineering and medicine. Driving nonlinear systems with external excitations can yield a plethora of intriguing and important phenomena-one of the most prominent being that of resonance. In the presence of additional harmonic or stochastic excitation, two exotic forms of resonance can arise: vibrational resonance or stochastic resonance, respectively. Several promising state-of-the-art technologies that were not covered in part 2 of this theme issue are discussed here. They include inter alia the improvement of image quality, the design of machines and devices that exert vibrations on materials, the harvesting of energy from various forms of ambient vibration and control of aerodynamic instabilities. They form an important part of the theme issue as a whole, which is dedicated to an overview of vibrational and stochastic resonances in driven nonlinear systems. This article is part of the theme issue 'Vibrational and stochastic resonance in driven nonlinear systems (part 2)'.

Evaluating the effect of subcrestal placement on platform switched short dental implants and von mises stress in D3 bone-A 3D FEM study

Aim

To investigate the effect of platform switched short dental implants and subcrestal placement on von Mises stress in the maxillary anterior region (D3 bone) by using three-dimensional finite element model analyses (3D FEM).

Materials and Methods

Biomechanical behaviour of von Mises stress in maxillary anterior region (D3) bone were stimulated with the help of 3D FEM with the help of ANSYS WORKBENCH version 17.5. The bone model had a cortical core of (1 mm) surrounding the inner cancellous core, which represents D3 bone. Two models were designed model 1 (6 x 4.6 mm), (7.5 x 4.6 mm) and model 2 (6 x 5.8 mm), (7.5 x 5.8 mm). Loads of 100, 200 N were applied at an angle of 0°, 15°, 30° along the long axis of the tooth model.

Results

In all model's cortical bone exhibited greater stress than cancellous bone. Greater stress was reported in axial direction at 30° then 15° and least at 0° irrespective of load applied. An increase in implant length (7.5 mm) did not exhibit any stress reduction in both the model but implant diameter (5.8 mm) led to reduction in von Mises stress in both the groups. Greater the force applied greater was stress in both bones irrespective of direction of force applied (200N). Lastly subcrestal (0.5 mm) placement has slight reduction in stress compared to equicrestal placement in both the groups.

Conclusion

Numerical results from the current study suggest that, for short implants, implant diameter is considered more effective design parameter than implant length. Current findings state that platform switch short subcrestal implants results in conservation of marginal bone loss along with better stress distribution around peri-implant regions in D3 bone. However, all models analyzed in this study showed development of von Mesies stresses within physiological limits for human cortical bone.

Delay-induced resonance suppresses damping-induced unpredictability

Combined effects of the damping and forcing in the underdamped time-delayed Duffing oscillator are considered in this paper. We analyse the generation of a certain damping-induced unpredictability due to the gradual suppression of interwell oscillations. We find the minimal amount of the forcing amplitude and the right forcing frequency to revert the effect of the dissipation, so that the interwell oscillations can be restored, for different time delay values. This is achieved by using the delay-induced resonance, in which the time delay replaces one of the two periodic forcings present in the vibrational resonance. A discussion in terms of the time delay of the critical values of the forcing for which the delay-induced resonance can tame the dissipation effect is finally carried out. This article is part of the theme issue 'Vibrational and stochastic resonance in driven nonlinear systems (part 1)'.

Construction of logic gates exploiting resonance phenomena in nonlinear systems

A two-state system driven by two inputs has been found to consistently produce a response mirroring a logic function of the two inputs, in an optimal window of moderate noise. This phenomenon is called logical stochastic resonance (LSR). We extend the conventional LSR paradigm to implement higher-level logic architecture or typical digital electronic structures via carefully crafted coupling schemes. Further, we examine the intriguing possibility of obtaining reliable logic outputs from a noise-free bistable system, subject only to periodic forcing, and show that this system also yields a phenomenon analogous to LSR, termed Logical Vibrational Resonance (LVR), in an appropriate window of frequency and amplitude of the periodic forcing. Lastly, this approach is extended to realize morphable logic gates through the Logical Coherence Resonance (LCR) in excitable systems under the influence of noise. The results are verified with suitable circuit experiments, demonstrating the robustness of the LSR, LVR and LCR phenomena. This article is part of the theme issue 'Vibrational and stochastic resonance in driven nonlinear systems (part 1)'.

Vibrational and stochastic resonances in driven nonlinear systems

Nonlinear systems are abundant in nature. Their dynamics have been investigated very extensively, motivated partly by their multidisciplinary applicability, ranging from all branches of physical and mathematical sciences through engineering to the life sciences and medicine. When driven by external forces, nonlinear systems can exhibit a plethora of interesting and important properties-one of the most prominent being that of resonance. In the presence of a second, higher frequency, driving force, whether stochastic or deterministic/periodic, a resonance phenomenon arises that can generally be termed stochastic resonance or vibrational resonance. Operating a system in or out of resonance promises applications in several advanced technologies, such as the creation of novel materials at the nano, micro and macroscales including, but not limited to, materials having photonic band gaps, quantum control of atoms and molecules as well as miniature condensed matter systems. Motivated in part by these potential applications, this 2-part Theme Issue provides a concrete up-to-date overview of vibrational and stochastic resonances in driven nonlinear systems. It assembles state-of-the-art, original contributions on such induced resonances-addressing their analysis, occurrence and applications from either the theoretical, numerical or experimental perspectives, or through combinations of these. This article is part of the theme issue 'Vibrational and stochastic resonance in driven nonlinear systems (part 1)'.

Growth, thermal, dielectric and mechanical properties of L-phenylalanine-benzoic acid: a nonlinear optical single crystal

An efficient amino acid family nonlinear optical single crystal L-phenylalanine-benzoic acid (LPB) was conveniently grown by slow evaporation technique at room temperature. The crystal system and the lattice parameters were analyzed by single crystal X-ray diffraction studies. The grown crystal has excellent transmission in the entire visible region and its lower cut-off wavelength was found to be 248 nm. The SHG efficiency of the grown crystal was found to be 1.6 times higher than that of KDP crystal. The Laser damage threshold value of LPB has been found to be 6.5 GW/cm(2). The sample was thermally stable up to 134°C. Microhardness, dielectric and AC/DC conductivity measurements were made along (001) plane and reported for the first time. Microhardness studies revealed that the sample belongs to hard nature. Frequency dependent dielectric constant was measured for different temperatures and found maximum dielectric constant of 14 for 363 K. Photoconductivity studies of LPB divulged its negative photoconducting nature.

Effect of multiple time-delay on vibrational resonance

We report our investigation on the effect of multiple time-delay on vibrational resonance in a single Duffing oscillator and in a system of n Duffing oscillators coupled unidirectionally and driven by both a low- and a high-frequency periodic force. For the single oscillator, we obtain analytical expressions for the response amplitude Q and the amplitude g of the high-frequency force at which resonance occurs. The regions in parameter space of enhanced Q at resonance, as compared to the case in absence of time-delay, show a bands-like structure. For the two-coupled oscillators, we explain all the features of variation of Q with the control parameter g. For the system of n-coupled oscillators with a single time-delay coupling, the response amplitudes of the oscillators are shown to be independent of the time-delay. In the case of a multi time-delayed coupling, undamped signal propagation takes place for coupling strength (δ) above a certain critical value (denoted as δu). Moreover, the response amplitude approaches a limiting value QL with the oscillator number i. We obtain analytical expressions for both δu and QL.

Novel vibrational resonance in multistable systems

We investigate the role of multistable states on the occurrence of vibrational resonance in a periodic potential system driven by both a low-frequency and a high-frequency periodic force in both underdamped and overdamped limits. In both cases, when the amplitude of the high-frequency force is varied, the response amplitude at the low-frequency exhibits a series of resonance peaks and approaches a limiting value. Using a theoretical approach, we analyse the mechanism of multiresonance in terms of the resonant frequency and the stability of the equilibrium points of the equation of motion of the slow variable. In the overdamped system, the response amplitude is always higher than in the absence of the high-frequency force. However, in the underdamped system, this happens only if the low-frequency is less than 1. In the underdamped system, the response amplitude is maximum when the equilibrium point around which slow oscillations take place is maximally stable and minimum at the transcritical bifurcation. And in the overdamped system, it is maximum at the transcritical bifurcation and minimum when the associated equilibrium point is maximally stable. When the periodicity of the potential is truncated, the system displays only a few resonance peaks.

Theory and numerics of vibrational resonance in Duffing oscillators with time-delayed feedback

The influence of linear time-delayed feedback on vibrational resonance is investigated in underdamped and overdamped Duffing oscillators with double-well and single-well potentials driven by both low frequency and high frequency periodic forces. This task is performed through both theoretical approach and numerical simulation. Theoretically determined values of the amplitude of the high frequency force and the delay time at which resonance occurs are in very good agreement with the numerical simulation. A major consequence of time-delayed feedback is that it gives rise to a periodic or quasiperiodic pattern of vibrational resonance profile with respect to the time-delayed parameter. An appropriate time delay is shown to induce a resonance in an overdamped single-well system which is otherwise not possible. For a range of values of the time-delayed parameters, the response amplitude is found to be larger than in delay-time feedback-free systems.

Diffusion dynamics and first passage time in a two-coupled pendulum system

We present the numerical investigation of diffusion process and features of first passage time (FPT) and mean FPT (MFPT) in a two-coupled damped and periodically driven pendulum system. The effect of amplitude of the external periodic force and phase of the force on diffusion constant, distribution of FPT, P(tFPT), and MFPT is analyzed. Normal diffusion is found. Diffusion constant is found to show power-law variation near intermittency and sudden widening crises while linear variation is observed in the quasiperiodic region. In the intermittency crisis the divergence of diffusion constant is similar to the divergence of mean bursting length. P(tFPT) of critical distances of state variable exhibit periodic multiple peaks with decaying amplitude. MFPT of critical distances also follows power-law variation. Diffusion constant and MFPT are sensitive to the phase factor of the periodic force.

Comparison of post amputation outcome in patients with type 2 diabetes from specialized foot care centres in three developing countries

OBJECTIVE

To evaluate post amputation outcome and associated complications in type 2 diabetic patients who had undergone major amputations in developing countries.

PATIENTS AND METHODS

A total of 526 (M:F; 369:157) subjects from three centers [India (IND), n=194, Bangladesh (BAN) n=177 and Tanzania (TAN) n=155 who had undergone amputation and subsequently visited the hospital were included in this analysis. Details on foot problems and associated complications were recorded.

RESULTS

The prevalence of amputations was similar in all centres. The history of minor amputation and foot deformity was high in BAN. Recurrence of foot ulceration was more in TAN (30%) than in IND (9%) and BAN (11%). Re-amputation rate was similar in all groups (3%). The use of artificial limb was most in BAN (97%). Myocardial infarction was more prevalent in IND (15%). In Tanzania, 31% had died during the follow-up period and it was 16% and 5% in IND and BAN. The causes of death were infection due to septicemia and cardiovascular events which finally led to multisystem organ failure.

CONCLUSION

The outcome following a major diabetic foot amputation was compared in three developing countries. Recurrence of foot infection was common in Tanzania. The most frequent causes of death were infection and cardiovascular events.

Analysis of vibrational resonance in a quintic oscillator

We consider a damped quintic oscillator with double-well and triple-well potentials driven by both low-frequency force f cos (omega)t and high-frequency force g cos (Omega)t with Omega>>omega and analyze the occurrence of vibrational resonance. The response consists of a slow motion with frequency omega and a fast motion with frequency Omega. We obtain an approximate analytical expression for the response amplitude Q at the low-frequency omega. From the analytical expression of Q, we determine the values of omega and g (denoted as omega(VR) and g(VR)) at which vibrational resonance occurs. The theoretical predictions are found to be in good agreement with numerical results. We show that for fixed values of the parameters of the system, as omega varies, resonance occurs at most one value of omega. When the amplitude g is varied we found two and four resonances in the system with double-well and triple-well cases, respectively. We present examples of resonance (i) without cross-well motion and (ii) with cross-well orbit far before and far after it. omega(VR) depends on the damping strength d while g(VR) is independent of d. Moreover, the effect of d is found to decrease the response amplitude Q.

Single and multiple vibrational resonance in a quintic oscillator with monostable potentials

We analyze the occurrence of vibrational resonance in a damped quintic oscillator with three cases of single well of the potential V(x)=1/2omega(0)(2)x(2)+1/4betax(4)+1/6gammax(6) driven by both low-frequency force f cos omegat and high-frequency force g cos Omegat with Omega >> omega. We restrict our analysis to the parametric choices (i) omega(0)(2), beta, gamma > 0 (single well), (ii) omega(0)(2), gamma > 0, beta < 0, beta(2) < 4omega(0)(2)gamma (single well), and (iii) omega(0)(2) > 0, beta arbitrary, gamma < 0 (double-hump single well). From the approximate theoretical expression of response amplitude Q at the low-frequency omega we determine the values of omega and g (denoted as omega(VR) and g(VR)) at which vibrational resonance occurs. We show that for fixed values of the parameters of the system when omega is varied either resonance does not occur or it occurs only once. When the amplitude g is varied for the case of the potential with the parametric choice (i) at most one resonance occur while for the other two choices (ii) and (iii) multiple resonance occur. Further, g(VR) is found to be independent of the damping strength d while omega(VR) depends on d. The theoretical predictions are found to be in good agreement with the numerical result. We illustrate that the vibrational resonance can be characterized in terms of width of the orbit also.

Limited joint mobility and plantar pressure in type 1 diabetic subjects in India

AIM

Limited joint mobility and plantar pressure in the foot has not been assessed in type 1 diabetes. The aim of this study was to investigate the joint mobility and plantar foot pressure in Asian Indian type 1 diabetic subjects and to see its association with duration of diabetes.

MATERIAL AND METHODS

The joint mobility and plantar pressure were measured in 115 consecutive subjects attending the foot clinic. The study groups were: Control- non diabetic controls (n=40) (M:F 19:21) and type 1 diabetic patients (n=75) (M:F 42:33). Joint mobility was assessed using a goniometer at two sites, in the subtalar joint and in the hallux. Plantar pressure was measured using the RS-Scan platform system. Data obtained on the metatarsal heads were used for analysis.

RESULTS

Patients with type 1 diabetes had significantly lesser joint mobility (p < 0.0001) and higher plantar pressure (p < 0.0001) compared with the control group. Duration of diabetes had an inverse association with joint mobility (p < 0.0001). The degree of joint mobility was more restricted in patients with longer duration of diabetes. Plantar pressure increased with increasing duration of diabetes.

CONCLUSION

In conclusion, type 1 diabetic patients in India had limited joint mobility which decreased further with longer duration of diabetes and they had high plantar pressure also.

Profile of diabetic foot complications and its associated complications--a multicentric study from India

AIM

The aims of this study were to determine. The prevalence of foot complications such as neuropathy, peripheral vascular disease (PVD), amputations and infections and the associated diabetic complications and practice of foot care among these subjects.

METHODS

A total of 1319 type 2 diabetic patients, were selected from four different centres across India. The centres were Diabetes Research Centre (DRC), Chennai, Government Rajaji Hospital (GRH), Madurai, Christian Medical College (CMC), Vellore and All India Institute of Medical Science (AIIMS), Delhi. Details were collected regarding foot problems and associated complications.

RESULTS

The prevalence of neuropathy was 15% (n=193) and PVD was 5% (n=64). Infections were present in 7.6% (n=100) of patients. The infection rate varied from 6-11% in the different centres. Nearly 3% of subjects had undergone a minor or major amputation.

DISCUSSION

This study found that the prevalence of infection was 6-11% and prevalence of amputation was 3% in type 2 diabetic patients. Neuropathy (15%) was found to be an important risk factor for diabetic foot infections. Effective foot care advice should be propagated to reduce the burden imposed by diabetic foot complication particularly in developing countries like India.

Amputation prevention initiative in South India: positive impact of foot care education

OBJECTIVE

To determine whether intensive treatment and education strategies for type 2 diabetic patients with high-risk diabetic foot disease helps in preventing foot amputations.

RESEARCH DESIGN AND METHODS

Participants included 4,872 consecutive type 2 diabetic patients (male-to-female ratio 3,422:1,450, mean (+/-SD) age 60.5 +/- 8.8 years, mean duration of diabetes 13.7 +/- 7.6 years) with high-risk diabetic foot disease. The patients were categorized as high-risk subjects according to the International Consensus on the Diabetic Foot. The three study groups were subjects with diabetes and neuropathy (group 1; n = 2,871), diabetic neuropathy with deformity (group 2; n = 235), and diabetic neuropathy with deformity and foot ulceration or peripheral vascular disease (group 3; n = 1,766). Neuropathy was diagnosed by biothesiometry. Peripheral vascular disease was diagnosed as an ankle brachial index <0.8. All the subjects were educated regarding diabetic foot disease and its complications and prevention. They were also instructed to visit the center if any sign of new lesions appeared.

RESULTS

Among the 1,259 group 3 subjects who came for follow-up, 718 (57%) strictly followed the advice given and 541 (43%) did not. Ulcers present during the recruitment had healed in 585 (82%) subjects who followed the advice, but in only 269 (50%) subjects who did not. A significantly larger proportion of subjects who did not follow the advice developed new problems (26%) and required surgical procedures (14%) compared with those who followed the advice (5 and 3%, respectively).

CONCLUSIONS

Strategies such as intensive management and foot care education are helpful in preventing newer problems and surgery in diabetic foot disease.

Effectiveness of different types of footwear insoles for the diabetic neuropathic foot: a follow-up study

OBJECTIVE

To compare the effectiveness of different types of footwear insoles in the diabetic neuropathic foot.

RESEARCH DESIGN AND METHODS

A sample of 241 consecutive diabetic patients (158 men and 83 women, age 57.5 +/- 9.6 years [mean +/- SD], and mean duration of diabetes 12.3 +/- 7.2 years) attending the foot clinic with previous foot ulceration and those considered at high risk of foot ulceration were included in the study. The study groups consisted of group 1, patients provided with sandals with insoles made with microcellular rubber (n = 100); group 2, with sandals with polyurethane foam (n = 59); group 3, with molded insoles (n = 32); and group 4, with their own footwear containing leather board insoles (n = 50). Neuropathy status was assessed using a biothesiometer. Plantar pressure was measured using the RS Scan inshoe pressure measurement system. Data obtained from the metatarsal heads were used as the peak pressure. The state of the sandals was assessed after 9 months. The patients were considered to have had an ulcer relapse when either a new ulcer appeared at the site of a previous one or a new foot ulcer appeared in a different area.

RESULTS

Patients who were using therapeutic footwear showed lower foot pressure (group 1, 6.9 +/- 3.6; group 2, 6.2 +/- 3.9; and group 3, 6.8 +/- 6.1 kPa; P = 0.0001), while those who used the nontherapeutic footwear showed an increased foot pressure (group 4, 40.7 +/- 20.5 kPa; P = 0.008). The occurrence of new lesions was significantly higher in patients in group 4 (33%) when compared with that of all other groups (4%).

CONCLUSION

Therapeutic footwear is useful to reduce new ulceration and consequently the amputation rate in the diabetic population.

Diffusion in a periodically driven damped and undamped pendulum

We study the diffusion process in a periodically driven damped and undamped pendulum. The effect of angular frequency omega of the external periodic force on the diffusion process is investigated. We show the occurrence of normal and anomalous diffusions in the undamped system. In the presence of damping, normal chaotic diffusion is found. Near certain bifurcation points, the phase velocity is found to be intermittent and the diffusion coefficient is found to exhibit power-law divergence. We argue that the divergence of the diffusion coefficient near the bifurcation points is similar to that of the average laminar lengths near them. The effect of bias on the dynamics is also discussed.

Vaccination with HIV-1 gp120 DNA induces immune responses that are boosted by a recombinant gp120 protein subunit

Small animals were immunized with plasmid DNA encoding HIV-1 envelope gp120 either intramuscularly by needle injection (mice and guinea pigs) or epidermally with the Accell gene gun (guinea pits). Subsequently, the animals were boosted with a recombinant gp120 protein subunit vaccine in an oil-in-water based adjuvant, MF59. Antibodies and cytotoxic T-lymphocyte (CTL) immune responses to the HIV envelope glycoprotein were observed in animals immunized with gp120 DNA derived from the HIV-1SF2 laboratory strain or from HIV-1 field isolates. Titers of ELISA antibodies and serum neutralizing antibodies against the HIV-1SF2 laboratory isolate were substantially increased in DNA-immunized animals following a single boost with recombinant gp120 protein subunit. This DNA prime/protein subunit boost immunization approach may be important for vaccination against infectious agents such as HIV for which it is difficult to raise strong antiviral humoral responses with DNA vaccination alone.

Bifurcation, chaos and suppression of chaos in FitzHugh-Nagumo nerve conduction model equation

We study the effect of constant and periodic membrane currents in neuronal axons described by the FitzHugh-Nagumo equation in its wave form. Linear stability analysis is carried out in the absence of periodic membrane current. Occurrence of chaotic motion, (i) in the absence of both constant and periodic membrane currents, (ii) with constant current only, (iii) with periodic membrane current only, and (iv) with both constant and periodic currents is investigated for specific parametric choices. We show how chaos sets in through a cascade of period doubling bifurcations. We then demonstrate the possibility of control of chaos using various control mechanisms. Specifically, we show the control of chaos by (i) adaptive control mechanism, (ii) periodic parametric perturbation and (iii) stabilization of unstable periodic orbits.

Degradation of CD4 following phorbol-induced internalization in human T lymphocytes. Evidence for distinct endocytic routing of CD4 and CD3

Exposure of T lymphocytes to phorbol esters induces endocytosis of CD4 and the CD3/T-cell receptor complex. We compared the pathway of CD4 internalization to that of CD3 following activation of human T lymphocytes with phorbol 12,13-dibutyrate (PDBu). Both CD3 and CD4 were rapidly internalized in response to PDBu, but only CD3, and not CD4, was recycled to the cell surface after removal of PDBu. In support of a degradative fate for internalized CD4, radioimmuno-precipitation studies revealed that the total amount of cellular CD4 was reduced by greater than 90% after exposure to PDBu for 4 h, whereas total CD3 remained constant. PDBu induced CD4 capping and localization consistent with sequestration in intracellular vesicles, presumably lysosomes, prior to becoming degraded. Lysosomotropic agents, such as NH4Cl, chloroquine, and monensin inhibited CD4 degradation, consistent with a lysosomal fate for CD4. Internalization and degradation of CD4 was blocked by staurosporine, an inhibitor of protein kinase C suggestive of a role for protein kinase C in the endocytic fate of CD4. The results of this study demonstrate that CD3 and CD4 follow distinct endocytic pathways which may be relevant to their having distinct roles in T cell activation and function.